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Campbell Scientific CPEC306 System Product Manual PDF
Summary of Content for Campbell Scientific CPEC306 System Product Manual PDF
Revision: 04/2022 Copyright 2019 2022 Campbell Scientific, Inc.
Product Manual
Table of contents 1. Introduction 1
2. Precautions 2
3. Initial inspection 2
4. Overview 3 4.1 CPEC306/310 system components 3 4.1.1 EC100 electronics 3 4.1.2 EC155 gas analyzer 4 4.1.3 CSAT3A sonic anemometer head 5 4.1.4 Pump module 5
4.2 CPEC306 6 4.3 CPEC310 8 4.4 Other components 10 4.4.1 CR6 data logger 10
4.5 Optional components 11 4.5.1 VOLT 116 11 4.5.2 CPEC310 scrub module 12 4.5.3 Carrying cases 13 4.5.4 Enclosure mounting options 13
4.6 Common accessories 13 4.7 Support software 15 4.8 Replacement parts 15 4.9 Theory of operation 18 4.9.1 EC155 gas analyzer 18 4.9.2 CSAT3A sonic anemometer head 19 4.9.3 CPEC310 valve module 19 4.9.4 CPEC series pump module 21
5. Specifications 22
6. Installation 23 6.1 Mounting 24 6.1.1 Support structure 24
Table of contents - i
6.1.2 Mount enclosures 24 6.1.3 Install eddy-covariance sensors 25
6.2 Plumbing 27 6.2.1 Zero/span with CPEC310 28
6.3 Wiring 29 6.3.1 Ground connections 29 6.3.2 Eddy-covariance sensor cables 30 6.3.3 Apply power 33
7. Configure the EasyFlux DL program 33 7.1 Operation 36 7.2 Set constants 36 7.2.1 Categories of constants 36 7.2.2 Accessing the constants 37
7.3 Edit input variables 45 7.4 Data retrieval 62 7.5 Output tables 62 7.6 Program sequence of measurement and corrections 107
8. Zero and span 108 8.1 User-initiated zero/span for CPEC310 115 8.1.1 CPEC310 auto zero/span 115 8.1.2 CPEC310 manual H2O span 118
8.2 User-initiated manual zero/span for CPEC306 119 8.2.1 CPEC306 manual zero 120 8.2.2 CPEC306 manual CO2 span 120 8.2.3 CPEC306 manual H2O span 121
9. Maintenance and troubleshooting 122 9.1 Enclosure desiccant 122 9.2 EC155 windows 122 9.3 EC155 molecular sieve bottles 123 9.4 Pump module filter 123 9.5 Testing wind offset 123
10. Repair 124
Appendix A. EasyFlux DL CR6CP process flow 125 A.1 Sequence of program functions 125
Table of contents - ii
A.1.1 Every SCAN_INTERVAL (default 100 ms) 125 A.1.2 Every SLOWSEQUENCE_SCAN_INTERVAL (default 5 sec) 127 A.1.3 Every 5 min 127 A.1.4 Every AVERAGING_INTERVAL (default 30 min) 128
Appendix B. Sampling site, regime, and mode 134
Appendix C. Wiring the CR6 and optional energy balance sensors 137 C.1 Overview 137 C.1.1 IRGA and sonic anemometer 137 C.1.2 VOLT 116 module 138 C.1.3 GPS receiver 138 C.1.4 Fine-wire thermocouple 139 C.1.5 Temperature and relative humidity probe 139 C.1.6 Radiation measurements, Option 1 140 C.1.7 Radiation measurements, Option 2 141 C.1.8 Precipitation gage 145 C.1.9 Soil temperature 146 C.1.10 Soil water content reflectometers 147 C.1.11 Soil heat flux plates 148 C.1.12 Self-calibrating soil heat flux plates 148
Appendix D. System diagnostic word 150
Appendix E. Quality grading 151
Appendix F. Using Swagelok fittings 153 F.1 Assembly 153 F.2 Common replacement parts 154
Appendix G. CPEC310 scrub module installation, operation, and maintenance 158 G.1 Theory of operation 158 G.2 Scrub module specifications 159 G.3 Installation 160 G.4 Maintenance 160
Appendix H. References 164
Table of contents - iii
1. Introduction The CPEC306 and CPEC310 (denoted as CPEC series from this point forward) are closed-path eddy-covariance (CPEC) flux systems used for long-term monitoring of atmospherebiosphere exchanges of carbon dioxide, water vapor, heat, and momentum. The series replaces the Campbell Scientific CPEC200, which was a complete turnkey system that included a closed-path gas analyzer (EC155), sonic anemometer head (CSAT3A), data logger (CR6), sample pump, and optional valve module for automated zero and span.
The CPEC series provides users with three options that cater to various eddy-covariance applications. All CPEC systems use a CR6 data logger and the closed-path version of the data logger program EasyFlux DL for automated post-processing flux calculations. All CPEC-series systems also include the latest improvements for compact packaging and mounting, as well as advancements in long-term automated operation. All CPEC-series systems now come with the current vortex intake technology on the EC155 gas analyzer.
The CPEC series is available as two systems:
l CPEC306 a mid-level, expandable system with pump module l CPEC310 an expandable system with pump module and 3-valve zero-and-span module
NOTE: This manual discusses two separate instrument packages, the CPEC306 and CPEC310, which are each suited to better address a wide variety of user needs. Throughout the manual, when the section being discussed applies to both systems, the systems will be referred to as the CPEC series. Where the manual discusses specifics that are unique to one of the systems, they will be specifically identified as a CPEC306 or CPEC310.
Before using any of the CPEC-series instrument configurations, please study:
l Precautions (p. 2) l Initial inspection (p. 2) l Installation (p. 23)
Operational instructions critical to the preservation of the system are found throughout this manual. Before using a CPEC series, please study the entire manual. Further information pertaining to the CPEC series can be found in the EC155 CO2/H2O Closed-Path Gas Analyzer manual, available at www.campbellsci.com .
CPEC306/310 Closed-Path Eddy-Covariance Systems 1
Other publications that may be helpful include:
l CR6 Measurement and Control Data Loggermanual l CSAT3B Three-Dimensional Sonic Anemometermanual l LoggerNet Data Logger Support Softwaremanual l ENC 10/12, 12/14, 14/16, 16/18 Enclosuresmanual l CM106B Tripodmanual l Tripod Installation Models CM110, CM115, CM120manual
2. Precautions General warnings
l Do not connect or disconnect the EC155 gas analyzer head or the CSAT3A sonic anemometer head from the EC100 electronics while the EC100 is powered. Doing so can result in unpredictable performance of the system or damage to the instrument head.
l Ground electrical components in the measurement systemthis is critical. Proper earth (chassis) grounding will ensure maximum electrostatic discharge (ESD) protection and higher measurement accuracy.
l Use care when connecting and disconnecting tube fittings to avoid introducing dust or other contaminants.
l Do not overtighten the tube fittings. Consult Using Swagelok fittings (p. 153) for information on proper connection.
l Design the power source for a CPEC-series system thoughtfully to ensure uninterrupted power. Contact Campbell Scientific for assistance, if needed.
l Retain all spare caps and plugs, as these are required when shipping or storing any CPEC- series system.
3. Initial inspection Upon receipt of the CPEC-series, inspect the packaging and contents for damage. File any damage claims with the shipping company. Contact Campbell Scientific to facilitate repair or replacement.
CPEC306/310 Closed-Path Eddy-Covariance Systems 2
Immediately check package contents against shipping documentation. Thoroughly check all packaging material for product that may be trapped inside. Contact Campbell Scientific about any discrepancies. Model numbers are found on each product. On cables, the model number is often found at the connection end of the cable. Check that correct lengths of cables are received.
4. Overview The CPEC306 and CPEC310 are closely related closed-path eddy-covariance systems, used for long-term monitoring of atmospherebiosphere exchanges of carbon dioxide, water vapor, heat, and momentum.
Both the CPEC306 and CPEC310 have options for a VOLT 116 that allows for additional sensors for energy balance and meteorological measurements. The CPEC310 is equipped with a 3-valve module to allow automatic zero and span.
The systems come as complete, standalone systems consisting of a Campbell Scientific EC100 electronics module, closed-path gas analyzer (EC155), sonic anemometer (CSAT3A), and sample pump. Systems come wired for a CR6 data logger that can be purchased with the system, or they can be wired by users who already have a CR6 data logger. CPEC306/310 system components (p. 3) describes the basic components of both systems. CPEC306 (p. 6) and CPEC310 (p. 8) describe the specifics of each system in greater detail.
4.1 CPEC306/310 system components The following sections describe the components that come standard with any of the CPEC-series systems.
4.1.1 EC100 electronics The EC100 electronics module (Figure 4-1 [p. 4]) controls the EC155 and CSAT3A. As a standalone enclosure, the EC100 must be mounted within 3.0 m (10.0 ft) of the EC155 and CSAT3A.
CPEC306/310 Closed-Path Eddy-Covariance Systems 3
Figure 4-1. EC100 electronics module
4.1.2 EC155 gas analyzer The EC155 is a closed-path infrared CO2/H2O gas analyzer. It shares integrated electronics (EC100 electronics) with the CSAT3A sonic anemometer head in CPEC systems. The EC155 includes a patented1/ vortex intake, which reduces intake maintenance and has an absolute pressure sensor in the sample cell for more accurate measurements and improved sample cell corrosion protection. The EC155 with vortex intake, shown in Figure 4-2 (p. 4), is included as part of both CPEC-series systems. For detailed information and specifications, see the EC155 CO2/H2O Closed-Path Gas Analyzermanual at www.campbellsci.com .
Figure 4-2. EC155 CO2/H2O closed-path gas analyzer
1/U.S. Pat. No. 9,217,692
CPEC306/310 Closed-Path Eddy-Covariance Systems 4
4.1.3 CSAT3A sonic anemometer head The CSAT3A, shown in Figure 4-3 (p. 5), is the Campbell Scientific 3D sonic anemometer sensor head. It shares integrated electronics (EC100 electronics) with the EC155 gas analyzer. The CSAT3A and EC155 are mounted on the same platform to reduce separation between the instruments. For more details on the CSAT3AH operation, see the CSAT3BH Three-Dimensional Heated Sonic Anemometermanual.
NOTE: The Campbell Scientific standalone sonic anemometer, CSAT3B, has its own electronics, whereas the CSAT3A shares the EC100 electronics with the EC155 gas analyzer to ensure optimal synchronization between the two sensors. The measurement specifications for the CSAT3A and CSAT3B are the same.
Figure 4-3. CSAT3A sonic anemometer
4.1.4 Pump module The CPEC-series systems use a small, low-power diaphragm pump to draw air through the EC155 sample cell. The pumping speed is automatically controlled to maintain the volumetric flow at the set point (3 to 9 LPM). The pump module is temperature controlled to keep the pump in its operating temperature range of 0 to 55 C. The pump module includes a large-capacity filter to protect the pump from contamination and dampen pressure fluctuations in the sample cell caused by the pump.
CPEC306 (p. 6) and CPEC310 (p. 8) describe each system in greater detail.
CPEC306/310 Closed-Path Eddy-Covariance Systems 5
4.2 CPEC306 Figure 4-4 (p. 6) shows a typical configuration of a CPEC306 system, which is a mid-level expandable system.
The two enclosures of the CPEC306 system are the EC100 electronics enclosure and data logger and pump module enclosure. The EC100 electronics are housed separately from the data logger (Figure 4-1 [p. 4]). The CR6 data logger is positioned within the CPEC306 enclosure (Figure 4-5 [p. 7] and Figure 4-6 [p. 7]). The CPEC306 enclosure also includes the pump module and has capacity for an optional VOLT 116 module (see VOLT 116 [p. 11]) for energy balance and meteorological measurements.
Figure 4-4. CPEC306 system
CPEC306/310 Closed-Path Eddy-Covariance Systems 6
Figure 4-5. CPEC306 system enclosure
Figure 4-6. Interior of CPEC306 system enclosure
CPEC306/310 Closed-Path Eddy-Covariance Systems 7
4.3 CPEC310 The CPEC310 includes the same features and components as the CPEC306, such as the capacity for a VOLT 116 (see Figure 4-8 [p. 9] and Figure 4-9 [p. 9]). Included with the CPEC310, however, is a 3-valve module that allows automatic zero and span. The CPEC310 can also be equipped with an optional scrub module providing a source of zero air for performing the zero-and-span procedures. A CPEC310 requires a CO2 reference tank (as shown in Figure 4-7 [p. 8]) and either a scrub module or a zero air reference tank to execute the automatic zero and span. (Campbell Scientific does not sell these reference tanks.)
Figure 4-7 (p. 8) shows a typical CPEC310 system, including a scrub module.
Figure 4-7. Fully configured CPEC310 system
CPEC306/310 Closed-Path Eddy-Covariance Systems 8
Figure 4-8. CPEC310 system enclosure
Figure 4-9. Interior of CPEC310 system enclosure
CPEC306/310 Closed-Path Eddy-Covariance Systems 9
The CPEC310 3-valve module (Figure 4-10 [p. 10]) is housed in the CPEC310 enclosure and is used to automate zero and CO2 span checks and automatically perform a field zero and field CO2 span on a user-defined interval. Field H2O span requires a dew point generator and cannot be automated because the dew point generator is a laboratory instrument and not designed for the long-term field deployment necessary for the automated zero-and-span operation. Therefore, H2O spans must be performed under manual control.
Figure 4-10. CPEC310 valve module
4.4 Other components The following section describes the CR6 data logger that is required for any of the CPEC-series systems. As many users already own the CR6 data logger, CPEC-series systems do not include the CR6 data logger in a standard system.
4.4.1 CR6 data logger The CR6 and EasyFlux DL are the core of the CPEC-series systems. They store raw data, process that data, store fluxes, allow for remote communications to the station, and provide diagnostic information about the system. Additionally, the CR6 (Figure 4-11 [p. 11]) is used for system control of the pump and valves.
CPEC306/310 Closed-Path Eddy-Covariance Systems 10
Figure 4-11. CR6 measurement and control data logger
4.5 Optional components The following section describes optional components that are available to expand the capabilities of the CPEC-series systems. Specific configurations will depend on specific site conditions, data requirements, and research goals.
4.5.1 VOLT 116 The VOLT 116 (the VOLT 116 replaced the CDM-A116; see Figure 4-12 [p. 11]) is a 24-bit analog input module that can increase the capacity of analog channels in a data logger system. The VOLT 116 has 16 additional channels available. The CPEC306 and CPEC310 enclosures both allow for the addition of a VOLT 116 module, making it possible to add energy balance and meteorological sensors. For more information on adding these sensors, see Configure the EasyFlux DL program (p. 33) and Wiring the CR6 and optional energy balance sensors (p. 137).
Figure 4-12. VOLT 116
CPEC306/310 Closed-Path Eddy-Covariance Systems 11
4.5.2 CPEC310 scrub module The CPEC310 scrub module provides a source of zero air used for zeroing the EC155. It consists of a pump and a three-stage molecular sieve and connects to the CPEC310 system enclosure. The scrub module (shown in Figure 4-13 [p. 12] and Figure 4-14 [p. 12]) eliminates the need for a cylinder of zero air. A cylinder of known CO2 is still required. By reducing the need for one of the two cylinders traditionally required for zero/span, the module is useful in locations where transporting and replacing cylinders is inconvenient. Additional information regarding installation and maintenance of the CPEC310 scrub module is found in CPEC310 scrub module installation, operation, and maintenance (p. 158).
Figure 4-13. CPEC310 scrub module enclosure
Figure 4-14. Interior of CPEC310 scrub module
CPEC306/310 Closed-Path Eddy-Covariance Systems 12
4.5.3 Carrying cases The EC155 and the CSAT3A may be ordered with optional carrying cases. If the carrying cases are not ordered, the sensors are shipped in cardboard boxes.
4.5.4 Enclosure mounting options The enclosures for any of the CPEC-series systems can be configured with one of several mounting options. The CPEC306 or CPEC310 system enclosure is similar to the Campbell Scientific ENC16/18 enclosure. The same mounting options are available:
l Triangular tower (UT10, UT20, or UT30) l Tripod mast 3.8 to 4.8 cm (1.5 to 1.9 in) diameter l Tripod leg (CM106B or CM106BK tripod only) l Large pole 10.2 to 25.4 cm (4.0 to 10.0 in) diameter l No mounting bracket
Consult the ENC 10/12, 12/14, 14/16, 16/18 Enclosuresmanual, available at www.campbellsci.com , for details on mounting bracket options.
4.6 Common accessories Several items may be required to complete the installation but are not included in a standard CPEC-series system. Some of the more common accessories are:
System power cable
Two power cables are required for a CPEC-series system: one for the main CPEC system and one for the EC100 electronics. The preferred power cable, CABLEPCBL-L, consists of a twisted red/black pair of 16-gauge (AWG) wires within a rugged Santoprene jacket. It is cut to the specified length, and the end is finished for easy installation.
NOTE: The -L designation after certain parts designates a cable or tube length in feet. The length is specified by the user at the time of order.
SDM cable
An SDM communication cable is required to connect the EC100 to the CPEC-series system enclosure. The preferred SDM cable is CABLE4CBL-L. This cable consists of four conductors with a shield and drain wire and a rugged Santoprene jacket. It is cut to the specified length, and the end is finished for easy installation.
CPEC306/310 Closed-Path Eddy-Covariance Systems 13
Pump tube
A tube must be used to connect the EC155 to the pump module. If the EC155 is within 50 ft of the CPEC series pump module, 3/8-in OD tubing is recommended. For longer distances (up to 500 ft), a larger 1/2-in OD tube is recommended to minimize pressure drop in the tube. Pre- swaged pump tube assemblies, 3/8-in OD or 1/2-in OD, are available for this purpose.
NOTE: The fittings on the EC155 and the pump module are sized for 3/8-in OD tubing. A reducer is required at each end for the larger tubing size. These reducers are supplied as part of the pre-swaged tube assembly.
Zero/span tubes
Tubes must be used to connect the EC155 and the zero and CO2 span cylinders to the valve module of the CPEC310. Bulk tubing with an aluminum core (to minimize diffusion through the tubing wall) and a UV-resistant, black, high-density polyethylene jacket can be cut to length and installed on site. The tubing should be 1/4-in OD to fit the Swagelok fittings on the EC155 and the valve module.
Minimize the length of these tubes to reduce the amount of equilibration time required after the zero or CO2 span cylinder is selected. One long tube is required to connect the valve module to the EC155, and two short tubes are required to connect the zero and CO2 span cylinders to the valve module. Pre-swaged tube assemblies are available for this purpose and are cut to a user- specified length.
USB memory card reader/writer
The USB memory card reader/writer is shown in Figure 4-15 (p. 14). It is a single-slot, high-speed reader/writer that allows a computer to read a memory card. When used with Campbell Scientific equipment, the memory card reader/writer typically reads data stored on microSD cards, but it can read many different types of memory cards.
Figure 4-15. USB memory card reader/writer
CPEC306/310 Closed-Path Eddy-Covariance Systems 14
4.7 Support software Several software products are available for interfacing a computer to the CR6 data logger.
EasyFlux DL
EasyFlux DL CR6CP for closed-path eddy-covariance systems is a CRBasic program that comes pre-installed into the CR6 that was purchased with this system. If a user has a system that was not ordered with a CR6 or has an older CPEC system, the EasyFlux DL program can be downloaded here: www.campbellsci.com/easyflux-dl . EasyFlux DL CR6CP enables a CR6 data logger to collect fully corrected fluxes of CO2, latent heat (H2O), sensible heat, ground surface heat flux (optional), and momentum from a Campbell Scientific closed-path eddy-covariance system with optional energy balance sensors. The program processes the eddy-covariance data using commonly applied corrections in scientific literature. A more detailed description of this program and how to properly configure it for your application can be found in Configure the EasyFlux DL program (p. 33).
PC400
PC400 is a free entry-level data logger support software that supports a variety of telecommunication options, manual data collection, and data display. PC400 includes an easy- to-use program generator (Short Cut), as well as full-featured program editors (CRBasic Editor, Edlog).
LoggerNet
LoggerNet is a full-featured software package that supports programming, communication, and data collection and display. LoggerNet consists of a server application and several client applications integrated into a single product. This package is recommended for applications that require telecommunications support and/or scheduled data retrieval, or for large data logger networks.
4.8 Replacement parts Vortex filter
For EC155 analyzers with a vortex intake, the bypass line from the vortex has a filter that will become clogged over time (typically many months) and requires replacement. The filter consists of a 25 m particulate filter with 1/4-in Swagelok nuts on either side, as shown in Figure 4-16 (p. 16). Replace the filter when the signal strength has dropped to 0.8 or less.
CPEC306/310 Closed-Path Eddy-Covariance Systems 15
Figure 4-16. Vortex filter for EC155 intake
Sonic wicks
The spare sonic wicks kit is used to replace the wicks on the CSAT3A. The kit includes three top wicks, three bottom wicks, an installation tool, and adhesive (see Figure 4-17 [p. 16]).
Figure 4-17. Spare sonic wick kit
Silica desiccant bags
Silica desiccant bags (Figure 4-18 [p. 16]) are used to desiccate the CPEC-series system enclosure and should be periodically replaced. These can be purchased in packs of 1, 4, or 20.
Figure 4-18. Single desiccant pack
CPEC306/310 Closed-Path Eddy-Covariance Systems 16
Humidity indicator card
The replacement humidity indicator card (Figure 4-19 [p. 17]) provides a visual reference of humidity level inside the enclosure.
Figure 4-19. Humidity indicator card
EC155 replacement molecular sieve
The EC155 has two small bottles filled with molecular sieve to remove CO2 and water vapor from inside the sensor head. Two bottles are included when purchasing the replacement.
Figure 4-20. EC155 replacement molecular sieve
Diaphragm pump
The pump module for any of the CPEC-series systems includes a small double-head diaphragm pump with a brushless DC motor (Figure 4-21 [p. 18]). The pump includes a speed-control input and a tachometer to measure actual pumping speed. It is mounted in an insulated, temperature- controlled box inside the CPEC-series system enclosure.
CPEC306/310 Closed-Path Eddy-Covariance Systems 17
Figure 4-21. Diaphragm pump used in CPEC-series systems
4.9 Theory of operation Any of the CPEC-series systems can be used for long-term monitoring of atmospherebiosphere exchanges of CO2, water vapor, heat, and momentum. These systems all include a closed-path gas analyzer (EC155), a sonic anemometer head (CSAT3A), and a sample pump, and they are designed to work only with a CR6 data logger. The CR6 can be purchased with either system, or, if a CR6 has previously been purchased, the CPEC-series system can be pre-wired for installation. The CPEC306 and CPEC310 allow for increased sensor capacity with a VOLT 116 module to accommodate additional sensor measurements. The CPEC310 comes equipped with a 3-valve module for automated zero and CO2 span of the EC155.
4.9.1 EC155 gas analyzer The EC155 (Figure 4-22 [p. 18]) is a closed-path, mid-infrared absorption gas analyzer that measures molar mixing ratios of CO2 and water vapor. More information about the operation of the EC155 can be found in the EC155 CO2/H2O Closed-Path Gas Analyzermanual at www.campbellsci.com .
Figure 4-22. EC155 gas analyzer
CPEC306/310 Closed-Path Eddy-Covariance Systems 18
4.9.2 CSAT3A sonic anemometer head The CSAT3A, as shown in Figure 4-23 (p. 19), is an ultrasonic anemometer sensor head for measuring wind speed in three dimensions. It shares integrated EC100 electronics with the EC155 gas analyzer. It is similar to the sensor head for the CSAT3B sonic anemometer, with the primary difference being that the CSAT3B can be used as a standalone anemometer because it includes independent electronics.
The CSAT3A uses three nonorthogonal pairs of transducers to sense the wind velocity vector. Each pair of transducers transmits and receives ultrasonic pulses to determine the time of flight, which is directly related to the speed of sound and the wind speed along the line between the pair of transducers. The CSAT3A transforms the results into orthogonal wind components ux, uy, and uz, referenced to the anemometer head.
The CSAT3A also determines the speed of sound for each transducer pair. These measurements are averaged and converted to sonic virtual temperature (Ts) based on the relationship between speed of sound and air temperature. For more detailed information and specifications, see the CSAT3B Three-Dimensional Sonic Anemometermanual, available at www.campbellsci.com .
Figure 4-23. CSAT3A sonic anemometer head
4.9.3 CPEC310 valve module The 3-valve module, shown in Figure 4-10 (p. 10), is housed in the CPEC310 enclosure and is used to perform manual and automated zero and CO2 span checks and manually and automatically perform a zero and CO2 span on a user-defined interval. As described in CPEC310 (p. 8), an H2O span requires a dew point generator and cannot be automated.
CPEC306/310 Closed-Path Eddy-Covariance Systems 19
NOTE: In this section and later in the manual, the names or labels on ports are denoted by the usage of bold font. Variable names in the data logger program and Public table are denoted by a different font that also appears bold.
The CPEC310 zero and CO2 span inlets are not bypass equipped, meaning that they flow only when selected. This allows the zero and CO2 span tanks to be continuously connected for automatic, unattended operation.
The H2O Span input is bypassed (vented to the atmosphere through the H2O Span Bypass outlet) when it is not selected to permit continuous flow. This allows a dew point generator to be connected directly to the H2O Span inlet. The internal pump of the dew point generator can push air into the valve module even when the H2O Span valve is not selected, minimizing errors caused by pressurization inside the dew point generator. When the H2O Span valve is selected, the dew point generator pushes moist air through the valve module to the EC155.
The CPEC310 pushes the zero/span flow backward through the EC155 sample cell and exhausts it through the intake tube to the atmosphere. Flow through the intake tube causes the sample-cell pressure to rise slightly above ambient pressure. The CPEC310 infers the flow rate from this pressure rise.
The EC155 has a pressure sensor in the sample cell to measure this pressure rise directly, but its accuracy is affected by a small offset drift. The accuracy of this pressure measurement can be improved by stopping all flow through the EC155, allowing the pressure in the sample cell to equilibrate with ambient pressure, and measuring the offset between sample cell and ambient pressures. This offset is then subtracted from subsequent measurements used to control the flow.
Because the pressure sensor offset can change over time, this offset is measured at the beginning of every zero/span cycle. This step requires at least 10 seconds to complete 5 seconds for the pressure to equilibrate and 5 seconds to average and store the pressure offset measurement.
The CPEC310 valve module has a proportional control valve to actively control the flow of zero- and-span gas to the EC155. The Easyflux DL program for the CPEC310 adjusts public variable valve_ctrl_press as needed for the measured flow valve_flow to reach the desired flow, as indicated by valve_flow_set_pt.
The default value for valve_flow_set_pt is 1.0 LPM. This flow is adequate for lower measurement heights and allows for a shorter tube between the valve module and the EC155, but the setting of a higher flow rate may be required with long zero/span delivery tubes used on tall towers. The proportional valve is opened fully during an H2O span operation to prevent pressurizing the dew point generator.
CPEC306/310 Closed-Path Eddy-Covariance Systems 20
NOTE: Even with higher flow rates, the time required to flush and equilibrate the delivery tubes on an extremely tall tower may make the automatic zero/span impractical. In this case, a manual zero/span as described in the EC155 CO2/H2O Closed-Path Gas Analyzermanual should be performed.
The CPEC310 valve module includes a heater and a fan to keep the valves within their operating range of 2 to 50 C. The valve heater turns on at 2 C and will stay on until the valve temperature warms to 4 C. The valve fan turns on at 50 C and stays on until the valve temperature drops to 48 C. To conserve power, temperature control is active just prior to and during the time when valves are in use. If the valves cannot be maintained within the temperature range, the valves are disabled. The valve module temperature control can be manually activated so that manual zero/span can be performed by the station operator on site or remotely. If starting from the minimum ambient temperature (30 C), the valves may take as much as 15 minutes to warm up to the operating range of 2 to 50 C.
4.9.4 CPEC series pump module The pump module for the CPEC-series systems pulls air through the system and exhausts it through the Exhaust fitting on the bottom of the enclosure. It uses a small double-head diaphragm pump with a brushless DC motor. This pump includes a speed control input and a tachometer to measure the actual pumping speed. It is mounted in an insulated, temperature- controlled box located inside the weathertight fiberglass enclosure. The pump module includes a large filter cartridge to dampen the pressure fluctuations from the pump and to protect the pump from particulates or debris.
The following sections describe operating parameters of the pump.
Pump speed
The pump tachometer is measured, converted to volumetric flow rate, and reported in public variable pump_flow_raw. A CPEC-series system will set the value of public variable pump_flow_duty_cycle to a value between 0 (off) and 1 (full speed) to adjust the pump speed as needed to match pump_flow_raw to the set point flow pump_flow_set_pt, which is a system configuration variable.
Pump inlet pressure
The measured inlet pressure of the pump is reported in public variable pump_press. This pressure will normally be slightly lower (~1 kPa) than the EC155 sample cell pressure due to the pressure drop in the pump tube.
CPEC306/310 Closed-Path Eddy-Covariance Systems 21
Pump temperature
The temperature of the pump module is reported in public variable pump_tmpr. The operating range of the pump is 0 to 55 C. If the pump temperature is outside this range, the CPEC-series system will disable the pump. The pump module has a heater (drawing 8 W while operational) that turns on if the pump temperature falls below 2 C. If the CPEC-series system is started at a cold temperature, it may take up to 50 minutes to warm the pump module (from 30 to 0 C). When it reaches 2 C, the heater will cycle on/off as needed to maintain this temperature.
The pump module has a fan (drawing 0.7 W while operational) that turns on if the pump temperature rises above 45 C. The fan will stay on until the pump temperature falls below 40 C.
The outlet of the pump connects the Exhaust fitting on the bottom of the pump module enclosure. This fitting has a screen to prevent insects or debris from entering when the pump is off.
5. Specifications System
Operating temperature: 30 to 50 C
Input voltage: 10.5 to 16.0 VDC
Power: 12 W (typical), 35 W (max; at cold startup)
System enclosure dimensions
CPEC306 or 310: 54.0 x 44.5 x 29.7 cm (21.3 x 17.5 x 11.7 in)
Designed ingress protection rating of EC100: IP651/
Weight basic system
CPEC306: 13.7 kg (30.3 lb)
CPEC310: 15.4 kg (33.9 lb)
VOLT 116 module: 0.9 kg (1.95 lb)
Pump module
Cable length: 3.0 m (10.0 ft)
Inlet connection: 3/8-in Swagelok
1/Not intended for marine environments
CPEC306/310 Closed-Path Eddy-Covariance Systems 22
Pressure sensor range: 15 to 115 kPa
Pumping speed: 3 to 9 LPM (automatically controlled at the set point, typically 7 LPM)
CPEC310 3-valve module
Inlets: Zero, CO2 span, and H2O span
Outlets: Analyzer and H2O bypass
Connections: 1/4-in Swagelok
Flow rate: 0.5 to 5 LPM (automatically controlled at user-entered set point)
Dimensions: 14.0 x 12.7 x 14.0 cm (5.5 x 5.0 x 5.5 in)
Weight: 1.5 kg (3.3 lb)
CPEC310 scrub module
Volume: 480.0 cm3 (29.29 in3) for each molecular sieve cylinder
Power: 2 W (typical)
Dimensions: 39.4 x 34.3 x 20.3 cm (15.5 x 13.5 x 8.0 in)
Weight: 9.6 kg (21.1 lb)
EC155 and CSAT3A specifications
See the EC155 CO2/H2O Closed-Path Gas Analyzermanual and CSAT3B Three-Dimensional Sonic Anemometermanual.
View compliance documentation at www.campbellsci.com/cpec300 .
6. Installation The following tools are required to install a CPEC-series system in the field. Additional tools may be required for a user-supplied tripod or tower.
l 9/16-in open-end wrench l 1/2-in open-end wrench l 11/16-in open-end wrench l Adjustable wrench
CPEC306/310 Closed-Path Eddy-Covariance Systems 23
l Small, flat-tip screwdriver (included with EC100 and CPEC-series system) l Large, flat-tip screwdriver l Sledgehammer (to drive grounding rod into the ground) l 3/16-in hex-key wrench (included with CM250 leveling mount)
6.1 Mounting 6.1.1 Support structure A CPEC-series system has three major components that must be mounted to a user-provided support structure.
Eddy-covariance sensors (EC155 and CSAT3A)
Mounted on a horizontal round pipe of 3.33 cm (1.31 in) outer diameter, such as a CM20X crossarm as in Figure 6-1 (p. 26).
EC100 electronics (denoted as closed-path eddy-covariance system for the CPEC)
Mounted within 3.0 m (10.0 ft) of the eddy-covariance sensors. The EC100 mounting bracket will accommodate a pipe at any orientation, with outer diameter from 2.5 to 4.8 cm (1.0 to 1.9 in).
CPEC306 or CPEC310 enclosure
Mounted where it can be accessed easily to retrieve data from the microSD cards in the data logger. The CPEC306 or CPEC310 enclosure is similar to the ENC16/18, with the same mounting options (such as tower, tripod, leg, or pole).
The following sections describe a typical application using a CM210 tripod and CM202 crossarm. The CM210 tripod and leg mounting options are ideal for a low eddy-covariance measurement height to minimize wind disturbance.
6.1.2 Mount enclosures Mount the EC100 electronics within 3.0 m (10.0 ft) of the eddy-covariance sensors (this measurement corresponds to the length of the cables on the EC155 and the CSAT3A).
For the EC100 and the system enclosure, open the sealed bag containing the desiccant packs and humidity card. Place two of the desiccant packs and the humidity indicator card in the mesh pocket in the enclosure door. Reseal the remaining two desiccant packs in the bag for later use.
NOTE: The EC100 should be mounted vertically to prevent the ingress of water from precipitation.
CPEC306/310 Closed-Path Eddy-Covariance Systems 24
The mounting bracket will accommodate a horizontal, vertical, or angled pipe from 2.5 to 4.8 cm (1.0 to 1.9 in) in diameter. See the EC155 CO2/H2O Closed-Path Gas Analyzermanual for details on configuring the EC100 mounting bracket.
CPEC306
The CPEC306 enclosure and the EC100 electronics are mounted as shown in Figure 4-4 (p. 6), with the two enclosures mounted on the legs of a tripod. They can also be mounted on a triangular tower or large-diameter pole, depending on the site requirements and the mounting options ordered.
CPEC310
The CPEC310 enclosure and the EC100 electronics are mounted as shown in Figure 4-7 (p. 8), with the two enclosures mounted on the legs of a tripod. They can also be mounted on a triangular tower or large-diameter pole, depending on the site requirements and the mounting options ordered. If a scrub module for zeroing the system has been included with the system, then that can be mounted on the leg of the tripod or near the CPEC310 enclosure. Cylinders of CO2 and zero air (needed in the absence of a scrub module) should be situated close to the base of the tower and secured with harnesses and additional poles to prevent the cylinders from falling over and damaging the system or injuring personnel.
6.1.3 Install eddy-covariance sensors Install a horizontal mounting crossarm at the height desired for the eddy-covariance measurement. This crossarm must be within 15 of horizontal to level the sonic anemometer. Point the crossarm into the predominant wind direction (for example, if the primary wind blows from the south, point the sensor to be facing south) to minimize wind disturbance caused by wind flowing past the mounting structure and eddy-covariance sensors. The outer diameter of the crossarm should be 3.3 cm (1.3 in). The CM202 crossarm is shown in Figure 6-1 (p. 26).
CPEC306/310 Closed-Path Eddy-Covariance Systems 25
Figure 6-1. CM210 mounting bracket on a tripod mast
The EC155 gas analyzer and CSAT3A sonic anemometer head are mounted on the end of the crossarm using the CM250 leveling mount and the CPEC series mounting platform. Figure 6-2 (p. 26) shows mounting for the EC155 with vortex intake. Adjust the tilt of the mounting platform to level the CSAT3A. For more details, see instructions in the EC155 CO2/H2O Closed-Path Gas Analyzermanual.
Figure 6-2. Mounting of EC155 and CSAT3A
CPEC306/310 Closed-Path Eddy-Covariance Systems 26
6.2 Plumbing Figure 6-3 (p. 27) depicts the plumbing required for the CPEC306, which includes the connection of the EC155 to the Inlet connector of the pump on the bottom of the CPEC306 enclosure.
Figure 6-4 (p. 28) depicts the plumbing for the CPEC310. The EC155 connects to the Inlet connector of the pump on the bottom of the CPEC310. To zero and span the EC155, 1/4-in OD tubing that has been swaged on both ends is used to connect the EC155 to the valve module. A CO2 cylinder and either a zero gas (ultra-pure nitrogen) cylinder or scrub module is connected to the valve module for zero and spanning. More information on zero-and-span procedures can be found in Zero and span (p. 108).
Figure 6-3. Plumbing connections for CPEC306
CPEC306/310 Closed-Path Eddy-Covariance Systems 27
Figure 6-4. Plumbing for CPEC310 with optional scrub module
6.2.1 Zero/span with CPEC310 The CPEC310 can perform automated zero (CO2 and H2O) and CO2 span of the EC155. The user must supply cylinders of zero air and CO2 span gas with appropriate regulators. If the user has chosen the optional CPEC310 scrub module, then no cylinder of zero air is required.
The rest of this section assumes the use of cylinders of compressed gas; see CPEC310 scrub module installation, operation, and maintenance (p. 158) for details on the scrub module.
Install cylinders in close proximity to the CPEC310 system enclosure. Each cylinder must have a pressure regulator to control the outlet pressure at 10 psig and must have a 1/4-in Swagelok fitting on the outlet. Connect regulators to the valve module inlets using 1/4-in OD tubing or pre- swaged tube assemblies. Minimize the length of these tubes to reduce the equilibration time after the zero or CO2 span cylinder is selected. Refer to Using Swagelok fittings (p. 153) for information on installing and replacing Swagelok fittings.
NOTE: Flow meters and needle valves are not needed because the CPEC310 valve module has a proportional-control valve to actively control the flow of zero-and-span gas to the EC155.
NOTE: Make sure no leaks exist in the regulators or the connections to the valve module. For automatic operation, the tank shutoff valves are left continuously open. A plumbing leak could cause the contents of the tank to be lost.
CPEC306/310 Closed-Path Eddy-Covariance Systems 28
NOTE: When inlets are not in use, replace the Swagelok plugs to keep the system clean.
Connect the valve module Analyzer outlet to the Zero/Span fitting on the back of the EC155 analyzer. Similar tubing or pre-swaged tube assembly is recommended for this connection. The length of this tube should also be minimized to reduce equilibration time.
Open the shutoff valves on the cylinders and set the pressure regulators for 10 5 psig delivery pressure.
NOTE: If the pressure is adjusted too high, slightly loosen the tube fitting to bleed off the excess pressure. Retighten the fitting when the proper setting is reached.
The H2O Span inlet is bypass equipped, allowing continuous flow. This inlet can be connected directly to the output of a dew point generator. The bypass on this inlet will avoid pressurizing the dew point generator.
NOTE: Some systems, such as the AP200 CO2/H2O Atmospheric Profile System, require a tee in the connection from the dew point generator to bleed off excess flow and avoid pressurizing the dew point generator. Do not use a tee to connect a dew point generator to the CPEC310.
6.3 Wiring 6.3.1 Ground connections Any CPEC-series system enclosure and the EC100 electronics must be earth grounded as illustrated in Figure 6-5 (p. 30). Ground the tripod and enclosures by attaching heavy gauge grounding wire (12 AWGminimum) to the grounding lug found on the bottom of each enclosure. The other end of the wire should be connected to earth ground through a grounding rod. For more details on grounding, see the grounding section of the CR6 Measurement and Control Data Loggermanual.
CPEC306/310 Closed-Path Eddy-Covariance Systems 29
Figure 6-5. Enclosure and tripod grounded to a copper-clad grounding rod
6.3.2 Eddy-covariance sensor cables Ensure the EC100 is not powered. Connect the EC155 gas analyzer head, EC155 sample cell, and CSAT3A sonic anemometer head to the EC100 electronics (Figure 6-6 [p. 30]).
Figure 6-6. EC155 and CSAT3A electrical connections; mounting hardware and tubing not shown
NOTE: CPEC-series instruments that are ordered with a CR6 are pre-wired with the appropriate EC100 wiring. Users who need to wire the system themselves should follow the next sections to wire the connection between the EC100 and the CPEC-series enclosure.
CPEC306/310 Closed-Path Eddy-Covariance Systems 30
Wire the SDM communications cable (CABLE4CBL-L) between the EC100 and the CPEC-series enclosure as shown in Figure 6-7 (p. 32) and Figure 6-8 (p. 32). Table 6-1 (p. 31) shows the color scheme of the SDM wires.
Table 6-1: SDM wiring
Description Wire color EC100 terminal DIN rail block
SDM data Green SDM-C1 SDM-C1
SDM clock White SDM-C2 SDM-C2
SDM enable Red/brown SDM-C3 SDM-C3
Signal ground Black Ground Ground
Shield Clear Ground Ground
NOTE: To bring cables into the enclosure, remove the cap from the cable feedthrough by loosening the thumbscrew and pulling the cap off.
NOTE: The CPEC-system wires connect to a DIN rail located inside the main enclosure. This DIN rail then connects to the CR6 data logger. To connect a wire to the DIN rail terminal blocks of the CPEC-system enclosure, insert a small screwdriver into the square hole to open the spring- loaded contacts. Insert the wire into the corresponding round hole and then remove the screwdriver. Gently tug the wire to confirm it is secure.
Ensure the CPEC-system enclosure is not powered, and wire the power cable (CABLEPCBL-L) from the EC100 electronics to the enclosure as shown in Figure 6-7 (p. 32) and Figure 6-8 (p. 32).
CPEC306/310 Closed-Path Eddy-Covariance Systems 31
Figure 6-7. Wiring the EC100 to a CPEC enclosure
Secure the SDM and power cables in the EC100 with a cable tie.
Figure 6-8. Wiring to EC100 electronics
CPEC306/310 Closed-Path Eddy-Covariance Systems 32
6.3.3 Apply power All CPEC-series systems require a 10.5 to 16.0 VDC power source. Its average power consumption is 12 W typically but will be slightly higher at cold temperatures, especially at startup in cold weather. In typical remote applications the power will be supplied from a user-provided 12 VDC battery system charged with solar panels.
NOTE: Before applying power, verify all tubes and cables have been connected according to the instructions above.
CAUTION: To reduce the risk of shorting the power supply, especially when using batteries, connect the power cable to the CPEC-series system first, then connect to the power source. Carefully design any DC power source to ensure uninterrupted power. If needed, contact Campbell Scientific for assistance.
Connect a power cable (CABLEPCBL-L) from the CPEC power terminals, as shown in Figure 6-8 (p. 32), to a user-supplied 12 VDC power supply.
Replace the cap on the CPEC enclosure feedthrough. Gently bend the cables back as you slide the cap on and rotate the cap to minimize the space around the cables. Tighten the thumbscrew to further relieve strain on the cable. This will also minimize air infiltration and extend the life of the enclosure desiccant packs.
NOTE: In very humid conditions or locations with insects and small rodents, it may be helpful to seal the cable feedthrough with plumbers putty.
7. Configure the EasyFlux DL program NOTE: This version of the manual applies to EasyFlux DL CR6CP version 1.04.
EasyFlux DL CR6CP is a CRBasic program that enables a CR6 data logger to collect fully corrected fluxes of CO2, latent heat (H2O), sensible heat, ground surface heat flux (optional), and
CPEC306/310 Closed-Path Eddy-Covariance Systems 33
momentum from any CPEC-series system with optional GPS and energy balance sensors. The program processes eddy-covariance data using commonly used corrections in scientific literature. Because the number of analog channels on the CR6 is limited, the program also supports the addition of a VOLT 116 analog input module, which allows expansion to include a full suite of energy balance sensors, thus enabling the program to calculate the ground surface heat flux and energy closure. Specifically, the program supports data collection and processing from the following sensors:
CPEC306
l EC155 CO2/H2O gas analyzer with EC100 electronics
l CAST3A sonic anemometer l Optional VOLT 116 analog channel expansion module l CR6 data logger l System enclosure (houses CR6, pump module, VOLT 116 module)
CPEC310
l EC155 CO2/H2O gas analyzer with EC100 electronics
l CAST3A sonic anemometer l Optional VOLT 116 analog channel expansion module l CR6 data logger l System enclosure (houses CR6, pump module, VOLT 116 module) l Valve module for automated zero and span of the gas analyzer l SDM-CD16S solid-state DC controller l Optional scrub module for providing zero gas (for example, gas without CO2 or H2O for zeroing the analyzer)
GPS receiver (optional, qty 0 to 1)
l GPS16X-HVS
Fine-wire thermocouple (optional, qty 0 to 1)
l FW05 l FW1 l FW3
CPEC306/310 Closed-Path Eddy-Covariance Systems 34
Biometeorology (biomet) and energy balance sensors (optional)
l Air temperature/relative humidity (RH) probe (qty 0 to 1) o HMP155A o EE181 o HygroVUE10
l Radiation measurement instrument o Option 1
n CS301 or CS320 pyranometer (qty 0 to 1) n CS310 quantum sensor (qty 0 to 1) n SI-111 infrared radiometer (qty 0 to 1)
o Option 2 n SN500SS or NR01 or CNR4 4-component net radiometers (qty 0 to 1; if using CNR4, a CNF4 ventilation and heater unit is also supported)
n CS310 quantum sensor (qty 0 to 1) l TE525MM rain gage (qty 0 to 1) l TCAV averaging soil thermocouple probe (qty 0 to 3) l Soil water content reflectometer (qty 0 to 3)
o CS650 o CS655
l Soil heat flux plate o Option 1: HFP01 soil heat flux plate (qty 0 to 3) o Option 2: HFP01SC self-calibrating soil heat flux plate (qty 0 to 3)
NOTE: It may be possible to customize the program for other sensors or quantities in configurations not described here. Contact Campbell Scientific for more information.
If the CPEC-series system is ordered with the CR6 factory-installed, the system is shipped with the EasyFlux DL CR6CP program installed. For users who will install a previously purchased CR6 into a CPEC-series system or for wiring of the optional sensors mentioned above, refer to Wiring the CR6 and optional energy balance sensors (p. 137).
CPEC306/310 Closed-Path Eddy-Covariance Systems 35
7.1 Operation Operating the EasyFlux DL CR6CP requires the user to enter or edit certain constants and input variables unique to the program or site. Constants are typically edited only once when first initializing the program. Site-specific variables are edited upon initial deployment and periodically as site conditions change (for example, canopy height is a variable that may need to be adjusted throughout a growing season). Refer to Set constants (p. 36) and Edit input variables (p. 45) for details.
Typical operation also includes periodic zeroing and spanning of the EC155 gas analyzer. Zero and span (p. 108) provides more details on this, either manually with the CPEC306 or automatically with the CPEC310.
7.2 Set constants 7.2.1 Categories of constants To begin program operation, the values for constants should be set or verified. Table 7-1 (p. 39) lists all constants with descriptions; Table 7-2 (p. 41) lists all constants with descriptions that are applicable only to CPEC-series systems using a VOLT 116. Generally, the constants fall into five categories:
1. System configuration constants
These constants indicate the model of the system, which measurement peripherals are being used (such as VOLT 116 or scrub module), and settings related to the system configuration (such as EC100 bandwidth or EC155 sample cell type).
2. Program function constants
These constants determine the timing of code execution, frequency of writing to output tables, memory allocation, and data transfer options, for example. In most cases, the default constants for these values can be maintained.
3. Sensor selection constants
All sensor selection constants begin with the prefix SENSOR. The value is set to TRUE in the constant table if the system includes the sensor. For example, if a system has a fine-wire thermocouple, the constant SENSOR_FW should be set to TRUE. When set to TRUE, the wiring in Table C-3 (p. 139) will apply to the sensor, and the data from that sensor will be included in the data output tables.
If a sensor is not used, ensure the constant is set to FALSE.
CPEC306/310 Closed-Path Eddy-Covariance Systems 36
4. Sensor quantity constants
The value for these constants indicates the number of each type of sensor in the system. For example, if three soil heat flux plates are being used, the constant NMBR_HFP would be set to 3.
5. Sensor calibration constants
Some sensors have unique parameters for their measurement working equations (for example, multipliers and/or offsets for linear working equations) that are used to convert raw measurements of voltage into the values applicable in analysis. Typically, these parameter values are found on the calibration sheet from the original manufacturer of the sensor. For example, if a CS301 pyranometer is being used, a unique multiplier is set in the following line of code: Constant PYRAN_MULT = 5. The comments in the code explain that the value entered is the sensor multiplier provided in the CS301 calibration sheet.
NOTE: Constants relating to a particular sensor have been grouped together with the sensor selection constant at the beginning, such that if the sensor selection constant is set to FALSE, then the other constants for that sensor may be ignored. For example, all constants dealing with the temp/RH probe are grouped together with the SENSOR_TMPR_RH constant at the top. If a temp/RH probe is not being used, SENSOR_TMPR_RH should be set to FALSE, thereby conditionally excluding the next four constants dealing with multipliers and offsets in the program.
7.2.2 Accessing the constants The constants may be accessed for editing by opening the program code in CRBasic Editor. Find the constants near the top of the program code, just after the introductory comments in a section titled USER-DEFINED CONFIGURATION CONSTANTS, subsection Start of Constants Customization Section (see Figure 7-1 [p. 38]). A user may also search for the word unique to find lines of code with user-editable constants.
Once changes are completed, the programmust be recompiled and saved. Save the program under a new or modified file name to keep track of different program versions. Finally, send the program to the CR6 using LoggerNet or PC400 user-interface software. After sending the program, its site-specific variables are ready to be reviewed and edited; see Edit input variables (p. 45).
CPEC306/310 Closed-Path Eddy-Covariance Systems 37
NOTE: After constants are edited in CRBasic Editor and the program is loaded and running on the data logger, constants may still be viewed by accessing the Const_Table using the CR1000KD keypad or through the LoggerNet Connect Screen.
Figure 7-1. Example screen from CRBasic Editor showing user-defined configuration constants
CPEC306/310 Closed-Path Eddy-Covariance Systems 38
Table 7-1: Program constants
Indented constant names are only applicable if the prior non-indented constant is true/applicable.
Constant name Default value Description
SCN_INTV 100 Measurement rate in milliseconds. Valid options: 50 (20 Hz) and 100 (10 Hz).
SLW_SCN_INTV 6000 Slow sequence measurement rate in milliseconds.
OUTPUT_INTV 30 Interval in minutes over which to compute statistics and fluxes.
DAY_FLUX_CRD 30 Number of days of data to write to each flux data output file stored on the card before beginning a new file.
DAY_TSRS_CRD 2 Number of days of data to write to each time series output file stored on the card before beginning a new file.
NTCH_FRQ_SLW 60
Analog integration parameter for measurements in the slow sequence. Options: 60 (filters 60 Hz noise) or 50 (filters 50 Hz noise). Choose the option that matches the AC power Hz at site.
ONE_FL_TABLE FALSE Set to TRUE to combine the Flux_CSFormat and anciliary Flux_Notes tables into one full or large table. Set to FALSE to keep the two tables separate.
CSAT_TYP_3AH FALSE Set to TRUE for heated CSAT3A option; set to FALSE for standard CSAT3A option.
SDM_CLCK_SPD 30 SDM clock bit period in microseconds (s). If long cables are used that result in skipped scans, this value should be increased. In most cases, the default is adequate.
EC100SDM_ADR 1 SDM address of the EC100.
BANDWIDTH 500/SCN_INTV
Bandwidth for measurements from the EC100. For spectral analysis and general use, set to half the sampling frequency (same as 500/SCN_INTV). If spectra are not considered, may be set to 20 Hz for any sample rate. Options: 5, 10, 12.5, or 20 Hz.
CEL_PRSS_TYP 1 Set to 1 to indicate an absolute pressure sensor in the sample cell.
CPEC306/310 Closed-Path Eddy-Covariance Systems 39
Table 7-1: Program constants
Indented constant names are only applicable if the prior non-indented constant is true/applicable.
Constant name Default value Description
CPEC306 FALSE Set to TRUE for CPEC306, else set to FALSE.
CPEC310 TRUE Set to TRUE for CPEC310, else set to FALSE.
CPEC310SCRUB FALSE Set to TRUE if the system has a scrub module, else set to FALSE.
ZRO_SPN_INTV 1 Number of days between each automatic zero and span.
ZRO_SPN_OFST 32
Number of minutes to offset the automatic zero/span. For example, if ZRO_SPN_INTV is 1, and ZRO_SPN_OFST is 32, then the auto zero/span will occur at 12:32AM each day.
TIME_ZRO_SPN 80
Number of seconds on sites or steps in the automatic zero and span (see Table 8-2 [p. 116]). Allow enough time for equilibration. For tall tower applications that have a large distance between CPEC310 system enclosure and the EC155 gas analyzer, this may need to be increased.
CHECK_ZERO TRUE Set to TRUE to measure and record the gas readings while zero gas is flowing but before the analyzer is zeroed. Set to FALSE to not measure and record.
SET_ZERO FALSE Set to TRUE to set the analyzer readings to zero while zero gas is flowing. Set to FALSE to not set the readings to zero.
CHECK_CO2SPN TRUE Set to TRUE to measure and record the gas readings while CO2 span gas is flowing but before setting the span. Set to FALSE to not measure and record.
SET_CO2SPN FALSE
Set to TRUE to set the analyzer CO2 readings to the span gas concentration while CO2 span gas is flowing. Set to FALSE to not set the readings to the CO2 span concentration.
SENSOR_GPS FALSE Set to TRUE if using a GPS16X sensor, else set to FALSE.
UTC_OFST 7 Difference between local time and UTC/GMT time in hours.
CPEC306/310 Closed-Path Eddy-Covariance Systems 40
Table 7-2: Program constants for CPEC-series systems in which a VOLT 116 is used
Constants in this table are only applicable and set to TRUE for CPEC306 and CPEC310 systems with a VOLT 116. Indented constant names are only applicable if the prior non-indented constant is true/applicable.
Constant name Default value Description
CDM_VOLT FALSE Set to TRUE for CPEC306 or CPEC310 if they include an optional VOLT 116 device.
SN_CDM_VOLT 0000 Serial number of VOLT 116.
Model_CDMVLT VOLT116 Model of VOLT 116.
CPI_CDM_VOLT 1 CPI address of VOLT 116.
CPI_DEVICE VOLT116 A custom name the user can give the VOLT 116. It must be in quotation marks.
SENSOR_FW FALSE Set to TRUE if using a fine wire thermocouple, else set to FALSE.
SENSOR_T_RH FALSE Set to TRUE if using a temp/RH probe, else set to FALSE.
TMPR_MULT 0.14 Multiplier for the raw temperature reading. Set to 0.14 for HMP155A or 0.1 for EE181.
TMPR_OFST 80.0 Offset for the temperature reading. Set to 80 for HMP155A or 40 for EE181.
RH_MULT 0.1 Multiplier for raw RH reading. Set to 0.1 for HMP155A or EE181.
RH_OFST 0.0 Offset for RH reading. Set to 0 for HMP155A or EE181.
SENSOR_HYGRO FALSE Set to TRUE if using a HygroVUE10 sensor, else set to FALSE.
HYGRO_SDIADR 1 HygroVUE10 SDI address.
SENSOR_CS301 FALSE
Set to TRUE if using a CS301 pyranometer, else set to FALSE. If TRUE, the following constants must be set to FALSE: SENSOR_CS320, SENSOR_NR01, SENSOR_CNR4, and SENSOR_SN500.
CPEC306/310 Closed-Path Eddy-Covariance Systems 41
Table 7-2: Program constants for CPEC-series systems in which a VOLT 116 is used
Constants in this table are only applicable and set to TRUE for CPEC306 and CPEC310 systems with a VOLT 116. Indented constant names are only applicable if the prior non-indented constant is true/applicable.
Constant name Default value Description
PYRAN_MULT 5 Multiplier for the pyranometer reading. Set to 5 for CS301. Units: Wm-2mV-1
SENSOR_CS320 FALSE
Set to TRUE if using a CS320 pyranometer, else set to FALSE. If TRUE, the following constants must be set to FALSE: SENSOR_CS301, SENSOR_NR01, SENSOR_CNR4, and SENSOR_SN500.
CS320SDI_ADR 2 SDI address of the CS320.
SENSOR_CS310 FALSE Set to TRUE if using a CS310, else set to FALSE. If TRUE, SENSOR_NR01, SENSOR_CNR4, and SENSOR_SN500 must be set to FALSE.
QUNTM_MULT 100 Units: molm-2s-1mV-1
SENSOR_SI111 FALSE Set to TRUE if using an SI-111, else set to FALSE. If TRUE, SENSOR_NR01, SENSOR_CNR4, and SENSOR_SN500 must be set to FALSE.
m0_SI111 1.41970e9 Enter the unique calibration parameter called m0 found on the sensor calibration sheet.
m1_SI111 7.84100e6 Unique sensor calibration parameter.
m2_SI111 82213 Unique sensor calibration parameter.
b0_SI111 -1.72150e7 Unique sensor calibration parameter.
b1_SI111 1.85020e5 Unique sensor calibration parameter.
b2_SI111 13114 Unique sensor calibration parameter.
SENSOR_NR01 FALSE
Set to TRUE if using an NR01, else set to FALSE. If TRUE, the following constants must be set to FALSE: SENSOR_ CNR4, SENSOR_SN500, SENSOR_CS301, SENSOR_ CS320, SENSOR_CS310, and SENSOR_SI111.
CPEC306/310 Closed-Path Eddy-Covariance Systems 42
Table 7-2: Program constants for CPEC-series systems in which a VOLT 116 is used
Constants in this table are only applicable and set to TRUE for CPEC306 and CPEC310 systems with a VOLT 116. Indented constant names are only applicable if the prior non-indented constant is true/applicable.
Constant name Default value Description
SENSOR_CNR4 FALSE
Set to TRUE if using a CNR4, else set to FALSE. If TRUE, the following sensors must be set to FALSE: SENSOR_ NR01, SENSOR_SN500, SENSOR_CS301, SENSOR_CS320, SENSOR_CS310, and SENSOR_SI111.
SENSOR_CNF4 FALSE Set to TRUE if using a CNF4 heating and ventilation unit. If set to TRUE, SENSOR_CNR4 must also be TRUE.
SW_IN_SNSTVT 15.0
If using an NR01 or CNR4, enter the unique sensitivity of the upward facing pyranometer as reported on the sensor calibration sheet. Units: Vm2W-1
SWOUT_SNSTVT 15.0 Unique sensitivity of the downward facing pyranometer. Units: Vm2W-1
LW_IN_SNSTVT 8.0 Unique sensitivity of the upward facing pyrgeometer. Units: Vm2W-1
LWOUT_SNSTVT 8.0 Unique sensitivity of the downward facing pyrgeometer. Units: Vm2W-1
SENSOR_SN500 FALSE
Set to TRUE if using an SN500SS, else set to FALSE. If TRUE, the following constants must be set to FALSE: SENSOR_NR01, SENSOR_CNR4, SENSOR_CS301, SENSOR_CS320, SENSOR_CS310, and SENSOR_SI111.
SN500SDI_ADR 3 SDI address of the SN500SS.
SENSOR_TE525 FALSE Set to TRUE if using a TE525-series rain gage, else set to FALSE.
TE525_MULT 0.1
If using a TE525-series rain gage, enter the multiplier. Units: mm per tip. Multiplier for TE525MM = 0.1 mm/tip as default, TE525 = 0.254 mm/tip, TE525WS = 0.254 mm/tip, TE525WS w/ 8-in funnel = 0.1459 mm/tip.
SENSOR_TCAV FALSE Set to TRUE if using a TCAV, else set to FALSE.
CPEC306/310 Closed-Path Eddy-Covariance Systems 43
Table 7-2: Program constants for CPEC-series systems in which a VOLT 116 is used
Constants in this table are only applicable and set to TRUE for CPEC306 and CPEC310 systems with a VOLT 116. Indented constant names are only applicable if the prior non-indented constant is true/applicable.
Constant name Default value Description
NMBR_TCAV 3 Number of TCAV probes used. Max: 3
SENSOR_CS65X FALSE Set to TRUE if a CS650 or CS655 is used, else set to FALSE.
NMBR_CS65X 3 Number of CS650 or CS655 probes used. Max: 3
CSSDI12_ADR1 4 SDI12 address of the first CS65X probe.
CSSDI12_ADR2 5 SDI12 address of the second CS65X probe.
CSSDI12_ADR3 6 SDI12 address of the third CS65X probe.
SENSOR_HFP01 FALSE Set to TRUE if using an HFP01, else set to FALSE. If TRUE, SENSOR_HFPSC must be set to FALSE.
NMBR_HFP 3 Number of HFP01 or HFP01SC sensors used. Max: 3
HFP_SNSTVT_1 62.0
If using heat flux plates, enter the unique sensitivity of the first plate as reported on the sensor calibration sheet. Units: Vm2W-1
HFP_SNSTVT_2 62.0 Unique sensitivity of the second heat flux plate. Units: Vm2W-1
HFP_SNSTVT_3 62.0 Unique sensitivity of the third heat flux plate. Units: Vm2W-1
SENSOR_HFPSC FALSE Set to TRUE (1) if using an HFP01SC, else set to FALSE (0). If TRUE, SENSOR_HFP01 must be set to FALSE.
HFP_OHM_1 95.0
Unique heater resistance in ohms of first HFP01SC as found in its calibration sheet. If HFP01 (non-self- calibrating) heat flux plates are being used, this constant is ignored.
CPEC306/310 Closed-Path Eddy-Covariance Systems 44
Table 7-2: Program constants for CPEC-series systems in which a VOLT 116 is used
Constants in this table are only applicable and set to TRUE for CPEC306 and CPEC310 systems with a VOLT 116. Indented constant names are only applicable if the prior non-indented constant is true/applicable.
Constant name Default value Description
HFP_OHM_2 95.0
Unique heater resistance in ohms of second HFP01SC as found in its calibration sheet. If HFP01 (non-self- calibrating) heat flux plates are being used, this constant is ignored.
HFP_OHM_3 95.0
Unique heater resistance in ohms of third HFP01SC as found in its calibration sheet. If HFP01 (non-self- calibrating) heat flux plates are being used, this constant is ignored.
CAL_INTV 1440 If using an HFP01SC, this is the time interval in minutes between auto calibrations.
7.3 Edit input variables Before data and fluxes are processed correctly, the user must review and edit variables. This is done most conveniently with a CR1000KD keypad. After the CR1000KD is connected to the CS I/O port of the CR6 data logger and the program is loaded and running, press Enter twice to access the main menu. Figure 7-2 (p. 49) shows an organizational schematic for all the keypad menus. Under the main menu, use the keypad down arrow to scroll down to each of the submenus. To select a submenu, highlight the desired submenu and press Enter. To return to a previous menu, press Esc. The three submenus titled Initial Configuratn, Site Var Settings, and Run Station contain the variables that must be reviewed. A description of the variables in each of these submenus is found in Table 7-3 (p. 50), Table 7-4 (p. 54), and Table 7-5 (p. 60), respectively.
If a CR1000KD is not available, an alternative option is to review and edit variables using LoggerNet. Under Table Monitor in the Connect Screen, select Public Table and then scroll to the appropriate variables. The last columns in Table 7-3 (p. 50), Table 7-4 (p. 54), Table 7-5 (p. 60) show the corresponding variable name in the Public Table. To change a value of a variable in the Table Monitor, click on the cell to the right of the variable name, type the new value, and press Enter. The values of user-input variables are stored in memory such that if the station loses power, the values will be retained.
CPEC306/310 Closed-Path Eddy-Covariance Systems 45
NOTE: Figure 7-2 (p. 49) is a schematic of the entire menu structure. When beginning operation of a system, the user must review and set variables in the following menus: Initial Configuratn, Site Var Settings, and Run Station. The other menus shown in the schematic relate to doing a zero and span of the gas analyzer. More details on zeroing and spanning are found in Zero and span (p. 108).
CPEC306/310 Closed-Path Eddy-Covariance Systems 46
System Control Initial Configuratn > Site Var Settings > Run Station > Attendant Zero/Span > Const_Table > System Menu
Initial Configuratn: Change Press Source > Shadow Correction > CSAT Heating Ctrl > CO2 Spn Gas H2O Span TDP Sample Flw *Zro/Spn Flw Zero span coeffs >
Change Press Source: Pick Sourc > Reset Sourc >
Pick Source: BB UB EB Set: TRUE
Reset zro/spn coefs: Rst CO2Zro coef > Rst CO2Spn coef > Rst H2OZro coef > Rst H2OSpn coef >
Shadow Correction: Pick Crrctn > Reset Crrctn >
Pick Crrctn: CORRCTN_ON CORRCTN OFF
Set: TRUE
Site Var Settings: Meas height Pck Surf typ > Canopy hght d, 0 = auto z0, 0 = auto GPS height Soil density C dry soil HFP depth IRGA Coord x IRGA Coord y FW Coord x FW Coord y Pick FW Diam > Sonic Azmth Latitude Pck Hmsph_NS > Longitude Pck Hmsph_EW > Altitude Planar Fit Alpha > Planar Fit Beta > Footprint Dis Intrst >
Pck Surf typ: CROP GRASS FOREST SHRUB BARELAND WATER ICE
Pick FW Diam: FW05DIA FW1_DIA FW3_DIA
Pck Hmsph_NS: NORTH SOUTH
Pck Hmpsh_EW: EAST WEST
Planar Fit Alpha: <=60or>=300 >60 & <=170 >170 & <190 >=190 & <300
Planar Fit Beta: <=60 or >=300 >60 & <=170 >170 & <190 >=190 & <300
Footprint Dis Intrst: <=60 or >=300 >60 & <=170 >170 & <190 >=190 & <300
Rst CO2Zro coef: Change coef Set change: TRUE
Set: TRUE
CSAT Heating Ctrl: User Ctrl On >
Rst CO2Spn coef: Change coef Set change: TRUE Rst H2OZro coef: Change coef Set change: TRUE
Rst CO2Spn coef: Change coef Set change: TRUE
CPEC306/310 Closed-Path Eddy-Covariance Systems 47
Run Station: Pump Tmpr Ok Pump Tmpr Pump Flow CSAT Error *CSAT HT Err IRGA Error *Auto Z/S on > Pump off > EC155_PW_on EC155 Messg EC155 Off >
Set: TRUE, FALSE
Set: TRUE, FALSE
Attendant Zero/Span: Valv/Scrub Tmpr Ctrl > Prfrm Field Zero > Prfrm Field CO2 Span > Prfrm Field H2O Span > Prfrm AUTO_ZS Cycle >
Set: TRUE, FALSE
Pump off: *PMP_OFF *FLD_MEA *AUTO_ZS **TRUE **FALSE
Valv/Scrub Tmpr Ctrl: Valv T Ok Valv T Scrb T Ok Scrb T V/S T Ctl On >
Pick ZRO_ALL: ZRO_ALL FLD_MEA AUTO_ZS
Prfrm Field Zero: *Chk_Set_Optn > *Pick ZRO_ALL > *Site *Sec On Site **Pump Off > CO2 umol/mol H2O mmol/mol IRGA Error *GasFlw L/min VALV T Error *SCRB T Error **Do Zero >
Set: TRUE
Chk_Set_Optn: CHK_OLY CHK_SET
Prfrm Field CO2 Span: *Chk_Set_Optn > *Pick SPN_CO2 > CO2 Spn Gas *Site *Sec On Site **Pump Off > CO2 umol/mol IRGA Error *GasFlw L/min VALV T Error **DO CO2 Span >
Chk_Set_Optn: CHK_OLY CHK_SET
Pick SPN_CO2: FLD_MEA ZRO_ALL SPN_CO2 SPN_H2O AUTO_ZS
Set: TRUE
Set: TRUE
Set: TRUE
Prfrm Field H2O Span: *Chk_Set_Optn > *Pick SPN_H2O > H2O Spn T_DP H2O Spn MX_R *Site *Sec On Site **Pump Off > H2O mmol/mol IRGA Error *GasFlw L/min VALV T Error T_DP_probe C **DO H2O Span >
Chk_Set_Optn: CHK_OLY CHK_SET
Pick SPN_H2O: FLD_MEA ZRO_ALL SPN_CO2 SPN_H2O AUTO_ZS
Set: TRUE
Set: TRUE
CPEC306/310 Closed-Path Eddy-Covariance Systems 48
Prfrm AUTO_ZS cycle: *Pick AUTO_ZS > CO2 Spn Gas *H2O Spn T_DP *H2O Span MX_R *Site *Sec On Site CO2 umol/mol Cell T_DP H2O mmol/mol *GasFlw L/min IRGA Error VALV T Error VALV Flw Err *SCRB T Error
Const_Table: SCN_INTV SLW_SCN_INTV OUTPUT_INTV DAY_FLUX_CRD DAY_TSRS_CRD NTCH_FRQ_SLW ONE_FL_TABLE CSAT_TYP_3AH SDM_CLCK_SPD EC100SDM_ADR BANDWIDTH CEL_PRSS_TYP CPEC306 CPEC310 CPEC310SCRUB ZRO_SPN_INTV ZRO_SPN_OFST TIME_ZRO_SPN CHECK_ZERO SET_ZERO CHECK_CO2SPN SET_CO2SPN SENSOR_GPS UTC_OFST
Const_Table Contd CDM_VOLT SN_CDM_VOLT Model_CDMVLT CPI_CDM_VOLT CPI_DEVICE SENSOR_FW SENSOR_T_RH TMPR_MULT TMPR_OFST RH_MULT RH_OFST SENSOR_HYRGO HYRGRO_SDIADR SENSOR_CS301 PYRAN_MULT SENSOR_CS320 CS320SDI_ADR SENSOR_CS310 QUNTM_MULT SENSOR_SI111 m0_SI111 m1_SI111 m2_SI111 b0_SI111 b1_SI111 b2_SI111
Const_Table Contd: SENSOR_NR01 SENSOR_CNR4 SENSOR_CNF4 SW_IN_SNSTVT SWOUT_SNSTVT LW_IN_SNSTVT LWOUT_SNSTVT SENSOR_SN500 SN500SDI_ADR SENSOR_TE525 TE525_MULT SENSOR_TCAV NMBR_TCAV SENSOR_CS65X NMBR_CS65X CSSDI12_ADR1 CSSDI12_ADR2 CSSDI12_ADR3 SENSOR_HFP01 NMBR_HFP HFP_SNSTVT_1 HFP_SNSTVT_2 HFP_SNSTVT_3 SENSOR_HFPSC HFP_OHM_1 HFP_OHM_2 HFP_OHM_3 CAL_INTV
Pick AUTO_ZS: AUTO_ZS FLD_MEA
Figure 7-2. Custom keypad menu; arrows indicate submenus (the single asterisk [*] marks variables that are only displayed if the system is a CPEC310, and the double asterisk [**]
marks variables that are only displayed if the system is a CPEC306)
CPEC306/310 Closed-Path Eddy-Covariance Systems 49
Table 7-3: Variables from Initial Configuratn menu
Station variable Default Description
Name of variable in Public table
(if no CR1000KD is available)
Change Press Source
Pick Sourc EB
Used to select the barometer to use for measurements of ambient pressure.
BB EC100 on-board basic barometer
UB User-supplied barometer
EB EC100 enhanced barometer
press_source 0 = BB 1 = UB 2 = EB
Reset Sourc FALSE
If the variable Pick Sourc has been changed, this variable must be set to TRUE to enable the change. The program will return Reset Sourc to FALSE once the change has been applied.
set_press_source_flg 1 = True 0 = False
Pick Crrctn CORRCTN_ OFF
Used to enable the Kaimal sonic transducer wind shadowing correction as described in the CSAT3B manual. CORRCTN_ON enables the correction, while CORRCTN_OFF disables it.
shadow_corr 1 = CORRCTN_ON 0 = CORRCTN_OFF
CPEC306/310 Closed-Path Eddy-Covariance Systems 50
Table 7-3: Variables from Initial Configuratn menu
Station variable Default Description
Name of variable in Public table
(if no CR1000KD is available)
Shadow Correction Reset Crrctn FALSE
If the variable Pick Crrctn has been changed, this variable must be set to TRUE to enable the change. Program will return Reset Crrctn to FALSE once change has been applied.
set_shadow_corr_flg 1 = True 0 = False
CSAT Heating Ctrl (only if heated sonic is used)
User Ctrl On FALSE Set variable to TRUE for CSAT3AH heating controls.
CSAT3H_ctrl_on 1 = True 0 = False
CO2 Spn Gas 400 ppm
Dry molar mixing ratio concentration of the CO2 span gas. A concentration close to ambient is recommended.
CO2_span_gas
H2O Span TDP 10 C
Dew point temperature of the H2O span gas (for example, the dew point temperature setting of the dew point generator).
Td_span_gas
CPEC306/310 Closed-Path Eddy-Covariance Systems 51
Table 7-3: Variables from Initial Configuratn menu
Station variable Default Description
Name of variable in Public table
(if no CR1000KD is available)
Sample Flw 8 Lmin-1
Set point for total flow into the gas analyzer.
Note: If the vortex intake is installed, a portion of this flow will be diverted to the vortex bypass. See the EC155 CO2/H2O Closed- Path Gas Analyzermanual for more details.
pump_flow_set_pt
Zro/Spn Flw 1 Lmin-1
Set point for flow of zero or span gas through the gas analyzer.
Note: Only applicable to a CPEC310 with valve module.
valve_flow_set_pt
Rst CO2Zro coef
Change coef FALSE
Used to restore gas analyzer coefficients to 1 or a previously user-recorded value. Enter desired value in Change coef and then set Set change variable to TRUE in order to apply. Program will return Set change to FALSE once change has been applied.
CO2_zero_coeff
Set change FALSE rst_CO2_zro_coef_flg
CPEC306/310 Closed-Path Eddy-Covariance Systems 52
Table 7-3: Variables from Initial Configuratn menu
Station variable Default Description
Name of variable in Public table
(if no CR1000KD is available)
Rst CO2Spn coef
Change coef FALSE
Used to restore gas analyzer coefficients to 1 or a previously user-recorded value. Enter desired value in Change coef and then set Set change variable to TRUE in order to apply. Program will return Set change to FALSE once change has been applied.
CO2_span_coeff
Set change FALSE rst_CO2_spn_coef_flg
Zero span coeffs: Reset zro/spn coefs
Rst H2OZro coef
Change coef FALSE
Used to restore gas analyzer coefficients to 1 or a previously user-recorded value. Enter desired value in Change coef and then set Set change variable to TRUE in order to apply. Program will return Set change to FALSE once change has been applied.
H2O_zero_coeff
Set change FALSE rst_H20_zro_coef_flg
Rst H2OSpn Coef
Change coef FALSE
Used to restore gas analyzer coefficients to 1 or a previously user-recorded value. Enter desired value in Change coef and then set Set change variable to TRUE in order to apply. Program will return Set change to FALSE once change has been applied.
H2O_span_coeff
Set change FALSE rst_H20_spn_coef_flg
CPEC306/310 Closed-Path Eddy-Covariance Systems 53
Table 7-4: Variables and settings in Site Var Settings menu
Station variable Units Default Description
Name of variable in Public table (if no CR1000KD is available)
Meas height m 2 Height of the center of eddy- covariance sensor measurement volumes above ground.
height_ measurement
Pck Surf typ GRASS Type of surface at measurement site; used to estimate displacement height.
surface_type 1 = CROP 2 = GRASS 3 = FOREST 4 = SHRUB 5 = BARELAND 6 =WATER 7 = ICE
Canopy hght m 0.5 Average height of the canopy. height_canopy
d m 0 (Auto) Displacement height; set to 0 forprogram to auto-calculate. displacement_user
z0 m 0 (Auto) Roughness length; set to 0 forprogram to auto-calculate. roughness_user
GPS height m 1 Height of the GPS reciever above ground surface; variable is omitted if GPS is not used.
height_GPS16X
Soil density kgm-3 1300 Average density of soil; variable is omitted if energy balance sensors are not used.
soil_bulk_density
C dry soil Jkg-1K-1 870 Specific heat of dry mineral soil; variable is omitted if energy balance sensors are not used.
cds
HFP depth m 0.08 Depth of soil heat flux plates; variable is omitted if energy balance sensors are not used.
thick_abv_HFP
CPEC306/310 Closed-Path Eddy-Covariance Systems 54
Table 7-4: Variables and settings in Site Var Settings menu
Station variable Units Default Description
Name of variable in Public table (if no CR1000KD is available)
IRGA Coord x m 0.15020 Distance along sonic x-axis between sonic sampling volume and EC155 gas analyzer intake.
separation_x_IRGA
IRGA Coord y m 0.03218 Distance along sonic y-axis between sonic sampling volume and EC155 gas analyzer intake.
separation_y_IRGA
FW Coord x m 0.02627
Distance along sonic x-axis between sonic sampling volume and fine-wire thermocouple; variable is omitted if no fine-wire thermocouple is used.
separation_x_FW
FW Coord y m 0.02306
Distance along sonic y-axis between sonic sampling volume and fine-wire thermocouple; variable is omitted if no fine-wire thermocouple is used.
separation_y_FW
Pick FW Diam m FW05_ DIA
Diameter of fine-wire thermocouple. User enters a numerical value or selects which fine-wire thermocouple is being used to load appropriate diameter: 1.2710-5 m for FW05_ DIA, 2.5410-5 m for FW1_DIA, and 7.6210-5 m for FW3_DIA; variable is omitted if no fine-wire thermocouple is used.
FW_diameter
Predefined constants: FW05_DIA FW1_DIA FW3_DIA
Sonic Azmth decimal degrees 0
Compass direction in which the sonic negative x-axis points (for example, compass direction in which sonic head is pointing).
sonic_azimuth
CPEC306/310 Closed-Path Eddy-Covariance Systems 55
Table 7-4: Variables and settings in Site Var Settings menu
Station variable Units Default Description
Name of variable in Public table (if no CR1000KD is available)
Latitude decimal degrees 41.766 Site latitude in degrees north or
south. Latitude
Pck Hmsph_NS NORTH Site latitudinal hemisphere; options are NORTH or SOUTH, relative to the equator.
hemisphere_NS 1 = North 1 = South
Longitude decimal degrees 111.855 Site longitude in degrees east or
west. Longitude
Pck Hmsph_EW WEST Site longitudinal hemisphere; options are EAST or WEST, relative to the prime meridian.
hemisphere_EW 1 = East 1 = West
Altitude m 1356 Site altitude, or elevation above sea level. altitude
<=60 or
>=300
decimal degrees 0
Planar-fit alpha angle used to rotate wind when the mean horizontal wind is blowing from the sector of 0 to 60 and 300 to 360 in the sonic coordinate system (that is, wind blowing into sonic head).1/
alpha_PF_60_300
>60 &
<=170
decimal degrees 0
Planar-fit alpha angle used to rotate wind when the mean horizontal wind is blowing from the sector of 60 to 170 in the sonic coordinate system (that is, wind blowing from sector left and behind sonic head).1/
alpha_PF_60_170
CPEC306/310 Closed-Path Eddy-Covariance Systems 56
Table 7-4: Variables and settings in Site Var Settings menu
Station variable Units Default Description
Name of variable in Public table (if no CR1000KD is available)
Planar Fit Alpha
>170 & <190
decimal degrees 0
Planar-fit alpha angle used to rotate wind when the mean horizontal wind is blowing from the sector of 170 to 190 in the sonic coordinate system (that is, wind blowing from behind sonic head).1/
alpha_PF_170_190
>=190 & <300
decimal degrees 0
Planar-fit alpha angle used to rotate wind when the mean horizontal wind is blowing from the sector of 190 to 300 in the sonic coordinate system (that is, wind blowing from sector right and behind sonic head).1/
alpha_PF_190_300
<=60 or
>=300
decimal degrees 0
Planar-fit beta angle used to rotate wind when the mean horizontal wind is blowing from the sector of 0 to 60 and 300 to 360 in the sonic coordinate system (that is, wind blowing into sonic head).1/
beta_PF_60_300
>60 &
<=170
decimal degrees 0
Planar-fit beta angle used to rotate wind when the mean horizontal wind is blowing from the sector of 60 to 170 in the sonic coordinate system (that is, wind blowing from left and behind sonic head).1/
beta_PF_60_170
CPEC306/310 Closed-Path Eddy-Covariance Systems 57
Table 7-4: Variables and settings in Site Var Settings menu
Station variable Units Default Description
Name of variable in Public table (if no CR1000KD is available)
Planar Fit Beta
>170 & <190
decimal degrees 0
Planar-fit beta angle used to rotate wind when the mean horizontal wind is blowing from the sector of 170 to 190 in the sonic coordinate system (that is, wind blowing from behind sonic head).1/
beta_PF_170_190
>=190 & <300
decimal degrees 0
Planar-fit beta angle used to rotate wind when the mean horizontal wind is blowing from the sector of 190 to 300 in the sonic coordinate system (that is, wind blowing from right and behind sonic head).1/
beta_PF_190_300
<=60 or
>=300 m 100z
Upwind distance of interest from station when the mean horizontal wind is blowing from the sector of 0 to 60 and 300 to 360 in the sonic coordinate system (that is, wind blowing into sonic head).
Note: Program will report the percentage of cumulative footprint from within this distance. The default value is 100 the aerodynamic height (z); z is the difference between measurement height and displacement height.
dist_intrst_60_300
CPEC306/310 Closed-Path Eddy-Covariance Systems 58
Table 7-4: Variables and settings in Site Var Settings menu
Station variable Units Default Description
Name of variable in Public table (if no CR1000KD is available)
Footprint Dis Intrst
>60 &
<=170 m 100z
Upwind distance of interest from station when the mean horizontal wind is blowing from the sector of 60 to 170 in the sonic coordinate system (that is, wind blowing from left and behind sonic head).
dist_intrst_60_170
>170 & <190 m 100z
Upwind distance of interest from station when the mean horizontal wind is blowing from the sector of 170 to 190 in the sonic coordinate system (that is, wind blowing from behind sonic head).
dist_instrst_170_190
>=190 & <300 m 100z
Upwind distance of interest from station when the mean horizontal wind is blowing from the sector of 190 to 300 in the sonic coordinate system (that is, wind blowing from right and behind sonic head).
dist_intrst_190_300
1/Leave all planar fit alpha and beta angles set to 0 to use Tanner and Thurtell (1969) method of double coordinate rotations, and have the rotation angles auto-calculated each averaging interval.
CPEC306/310 Closed-Path Eddy-Covariance Systems 59
Table 7-5: Variables from the Run Station menu
Variable name Default Description
Name of variable in Public table
(if no CR1000KD is available)
Pump Tmpr Ok
A display (read-only) variable indicating whether pump temperature is within its operating range.
pump_tmpr_ok
Pump Tmpr A display (read-only) variable showing temperature of the pump in C.
pump_tmpr
Pump Flow 8.0 Lmin-1
A display (read-only) variable showing volumentric air flow to the pump; if using vortex intake, this includes flow through both sample cell and vortex bypass.
pump_flow
CSAT Error
System diagnostic word; if set to 0, no error conditions are detected. (For more details, see System diagnostic word [p. 150].)
sonc_er
CSAT HT Err
System diagnostic word; if set to 0, no error conditions are detected. (For more details, see System diagnostic word [p. 150].)
sonc_htng_er
IRGA Error
System diagnostic word; if set to 0, no error conditions are detected. (For more details, see System diagnostic word [p. 150].)
irga_er
CPEC306/310 Closed-Path Eddy-Covariance Systems 60
Table 7-5: Variables from the Run Station menu
Variable name Default Description
Name of variable in Public table
(if no CR1000KD is available)
Auto Z/S on FALSE
Set to TRUE to initiate an automatic zero and CO2 span of gas analyzer; system will return Auto Z/S on to FALSE once the zero/span is initiated and will return to eddy- covariance field measurements upon completion of the zero/span. Variable is omitted if the system is a CPEC306 (that is, no valve module).
prfm_auto_zero_span_flg
Pump off FALSE
For CPEC306 systems, select TRUE to disable the pump and FALSE to enable the pump.
For CPEC310 systems, select PMP_ OFF to disable the pump, FLD_MEA to re-enable pump and resume normal eddy-covariance measurements, or AUTO_ZS to initiate an automatic zero/span cycle.
pump_off_flg
EC155_PW_on A display (read-only) variable indicating whether the EC155 is powered on.
EC155_actual_pwr_on
EC155 Messg A display (read-only) string describing current status of the EC155.
message
EC155 Off FALSE Set to TRUE to power down the EC155 and FALSE to power on the EC155.
ec155_pwr_off_flg
CPEC306/310 Closed-Path Eddy-Covariance Systems 61
7.4 Data retrieval The program stores a very limited amount of data to the internal CPU of the data logger, so a microSD flash card should be used with the CR6. Table 7-6 (p. 62) shows the number of days of data a 2 GB, 8 GB, and 16 GB card will typically hold before the memory is full and data starts to be overwritten. For a real-time estimate of number of days remaining on the card, refer to the public variable card_storage_available_days.
In cases where real-time remote monitoring is desired, various telemetry options (such as cellular or radio) are available to transmit the processed flux data. Certain conditions may also allow remote transmittal of time series data. Contact Campbell Scientific for more details.
Table 7-6: microSD flash card fill times
microSD flash card size
Fill time with gas analyzer and sonic only
Fill time with gas analyzer, sonic, FW, and biomet/energy
balance sensors1/
2 GB ~29 days ~23 days
8 GB ~121 days ~92 days
16 GB ~242 days ~184 days 1/Biomet and energy balance sensors used for this fill time estimate include the following: HMP155A, CS301, CS310, SI-111, TE525MM, TCAV (qty 3), CS655 (qty 3), and HFP01 (qty 3).
NOTE: The microSD flash cards from various manufacturers may have slightly different memory sizes on their 2 GB, 8 GB, and 16 GB cards, respectively. Also, as a card ages, some of its sectors may become unusable, decreasing the available memory. Fill time estimates given in Table 7- 6 (p. 62) are approximations for new cards.
CAUTION: Campbell Scientific recommends and supports only the use of microSD cards obtained from Campbell Scientific. These cards are industrial grade and have passed Campbell Scientific hardware quality testing. Use of consumer grade cards substantially increases the risk of data loss.
7.5 Output tables Besides the Const_Table (see Set constants [p. 36]) and the standard Public, Status, CPI Status, and DataTableInfo tables that the data logger reports, the program has eight output tables. Table 7-7 (p. 63) gives the names of these output tables, along with a short description, the
CPEC306/310 Closed-Path Eddy-Covariance Systems 62
frequency at which a record is written to the table, and the amount of memory allocated from the CPU and microSD card for each table.
NOTE: Variable naming conventions used by AmeriFlux and other flux networks have been adopted. Additionally, an EasyFlux output table called Flux_AmeriFluxFormat reports the data variables in the order and format prescribed by AmeriFlux (see http://ameriflux.lbl.gov/data/aboutdata/data-variables/ ).
The Flux_CSFormat and Flux_Notes tables may have some of the same outputs as they did in prior versions of closed-path flux system programs, although variable names have been updated to conform to AmeriFlux convention. If the user would prefer to have the data fields contained in the Flux_Notes table appended to the end of the Flux_CSFormat table, rather than being placed in a separate output table, then the user should change the constant ONE_FULL_TABLE from FALSE to TRUE. See Set constants (p. 36).
Table 7-7: Data output tables
Table name Description Recording interval
Memory on CR6 CPU
Memory on microSD card
Time_Series
Time series data, aligned to account for
electronic delays
SCAN_ INTERVAL
(default 100 ms)
Auto-Allocate (typically less than 1 hour)
Time_Series is broken up into files of size
DAY_TSRS_CRD (default is 1-day files); see Table 7-6 (p. 62) for estimates
of total days
Diagnostic
Most recent diagnostic flags
from gas analyzer and
sonic anemometer
SCAN_ INTERVAL
(default 100 ms)
1 record (most recent scan) 0 records
EC100_Config_ Notes
Settings for the gas analyzer and
sonic anemometer
When settings are changed or system is power
cycled
128 records 10*DAY_FLUX_CRD record (default 300
records)
CPEC306/310 Closed-Path Eddy-Covariance Systems 63
Table 7-7: Data output tables
Table name Description Recording interval
Memory on CR6 CPU
Memory on microSD card
Flux_ AmeriFluxFormat
Processed flux and statistical data following AmeriFlux reporting
conventions and order
OUTPUT_ INTERVAL
(default 30 min)
NMBR_DAY_ CPU
(default 7 days)
Broken up into multi- day files, where the
number of days on each file is defined by DAY_ FLUXCRD (default 30 days); see Table 7-6 (p. 62) to calculate number
of files
Flux_CSFormat Processed flux and statistical
data
OUTPUT_ INTERVAL
(default 30 min)
NMBR_DAY_ CPU
(default 7 days)
Broken up into multi- day files, where the
number of days on each file is defined by DAY_ FLUXCRD (default 30 days); see Table 7-6 (p. 62) to calculate number
of files
Flux_Notes
Intermediate variables, station constants, and correction
variables used to generate flux
results
OUTPUT_ INTERVAL
(default 30 min)
NMBR_DAY_ CPU
(default 7 days)
Broken up into multi- day files, where the
number of days on each file is defined by DAY_ FLUXCRD (default 30 days); see Table 7-6 (p. 62) to calculate number
of files
CPEC306/310 Closed-Path Eddy-Covariance Systems 64
Table 7-7: Data output tables
Table name Description Recording interval
Memory on CR6 CPU
Memory on microSD card
ZeroSpan_Check_ Notes
Summary of field calibration data at the time of a zero or span
check
When a zero or span check is performed
NUMBR_ RCRDS_CHCK_ NOTES_CPU (default 30 records or
approximately 1 month)
NUMBR_RCRDS_CHCK_ NOTES_CRD (default 1,398 records or
approximately 1 year)
System_Operatn_ Notes
Records any change in
system status
When there is a change in
system status
NMBR_ RCRDS_ OPRTN_
NOTES_CPU (default 24 records)
NMBR_RCRDS_OPRTN_ NOTES_CRD (default
1,198 records)
Table 7-8 (p. 65) through Table 7-15 (p. 107) give a description of all data fields found in each data output table and when each data field is included in the table.
NOTE: Prior to coordinate rotations, the orthogonal wind components from the sonic anemometer are denoted as Ux, Uy, and Uz. Following coordinate rotations, the common denotation of u, v, and w is used, respectively.
NOTE: Variables with _R denote that the value was computed after coordinate rotations were done. Variables with _F denote that the value was calculated after frequency corrections were applied. Similarly, _SND and _WPL refer to variables that have had the SND correction or the WPL correction applied, respectively.
Table 7-8: Data fields in the Time_Series output table
Data field name Units Description Data field included
Ux ms-1 Wind speed along sonic x-axis Always
Uy ms-1 Wind speed along sonic y-axis Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 65
Table 7-8: Data fields in the Time_Series output table
Data field name Units Description Data field included
Uz ms-1 Wind speed along sonic z-axis Always
T_SONIC deg C Sonic temperature Always
diag_sonic Raw sonic diagnostic value (0 indicates no diagnostic flags set) Always
CO2 molmol-1 CO2 dry molar mixing ratio Always
H2O mmolmol-1 H2O dry molar mixing ratio Always
diag_irga Raw gas analyzer diagnostic value (0 indicates no diagnostic flags set) Always
TA_1_1_1 deg C Air temperature calculated from sonic temperature and humidity Always
T_cell deg C Sample cell temperature Always
PA_cell kPa Air pressure inside sample cell Always
CO2_sig_strgth CO2 signal strength Always
H2O_sig_strgth H2O signal strength Always
PA_diff kPa Differential pressure (difference between sample cell pressure and ambient pressure)
Always
PA kPa Ambient pressure Always
pump_flow Lmin-1 Volumetric air flow to pump; if using vortex intake, this includes sample flow and vortex bypass flow
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 66
Table 7-8: Data fields in the Time_Series output table
Data field name Units Description Data field included
sampling_regime Binary number
For CPEC310, this identifies the current sampling regime (bits 0 through 3 correspond to the current sampling site, and bit 4 is the omit flag); for computing fluxes, filter all values 1 (1 corresponds to site 1, which is sampling ambient air with no omit flag set; see Sampling site, regime, and mode [p. 134] for more information on sampling sites and regimes)
If system is a CPEC310
FW deg C Air temperature measured by fine-wire thermocouple
If FW05, FW1, or FW3 is used
Table 7-9: Data fields in the Diagnostic output table
Data field name Description Data field included
sonc_er Sonic error flag (TRUE or 1 if any sonic diagnostic flag detected) Always
irga_er EC155 error flag (TRUE or 1 if any irga diagnostic flag detected) Always
pump_tmpr_error Pump temperature error flag Always
pump_flw_error Pump flow error flag Always
valve_T_error Valve temperature error flag If CPEC310 with valve module is used
valve_flw_error Valve flow error flag If CPEC310 with valve module is used
scrub_T_error Scrub temperature error flag If scrub module is used
diag_sonic CSAT3A diagnostic word; if 0, no error flags set (see EC155 CO2/H2O Closed-Path Gas Analyzer manual for more details)
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 67
Table 7-9: Data fields in the Diagnostic output table
Data field name Description Data field included
sonic_amp_l_f Amplitude low diagnostic flag Always
sonic_amp_h_f Amplitude high diagnostic flag Always
sonic_sig_lck_f Signal lock diagnostic flag Always
sonic_del_T_f_f Delta temperature diagnostic flag Always
sonic_aq_sig_f Acquiring signal diagnostic flag Always
sonic_cal_err_f Calibration error diagnostic flag Always
CSAT3H_user_ctrl_flg CSAT3AH heating control start If CSAT3AH is used
CSAT3H_ctrl_on Control status of CR300 in controller (TRUE if on; FALSE if off) If CSAT3AH is used
T_trnsd_uppr Average temperature of upper transducer If CSAT3AH is used
T_trnsd_lwr Average temperature of lower transducer If CSAT3AH is used
pwr_trnsds Power heating transducers If CSAT3AH is used
trnsd_heater_on If TRUE, transducer heater is on; FALSE if off If CSAT3AH is used
trnsd_heater_fail If TRUE, transducer heater failure detected If CSAT3AH is used
T_arm_uppr Average temperature of upper arm If CSAT3AH is used
T_arm_lwr Average temperature of lower arm If CSAT3AH is used
pwr_arms Power heating arms If CSAT3AH is used
arm_heater_on If TRUE, arm heater is on; FALSE if off If CSAT3AH is used
arm_heater_fail If TRUE, arm heater failure detected If CSAT3AH is used
pwr_trnsds_arms Heater power If CSAT3AH is used
diag_sonic_slwintv Aggregated diagnosis code within a slow scan interval If CSAT3AH is used
trnsd_ice_wet_lck Number of seconds in the interval that transducers were locked due to ice and wet If CSAT3AH is used
heating_inaplcbl_f Flag to indicate sonic heating would be inapplicable to improve the measurements If CSAT3AH is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 68
Table 7-9: Data fields in the Diagnostic output table
Data field name Description Data field included
com_rslt_get Failure times in communication of data logger getting data from CR300 If CSAT3AH is used
com_rslt_snt Failure times in communication of data logger sending data to CR300 If CSAT3AH is used
T_amb_ctrl Average ambient air temperature of controller If CSAT3AH is used
RH_amb_ctrl Average ambient relative humidity of controller If CSAT3AH is used
T_DP_amb_ctrl Average ambient dew point temperature of controller If CSAT3AH is used
diag_irga EC155 diagnostic word; if 0, no error flags set (see EC155 CO2/H2O Closed-Path Gas Analyzer manual for more details)
Always
irga_bad_data_f Any gas analyzer diagnostic flag is set Always
irga_gen_fault_f General system fault diagnostic flag Always
irga_startup_f Startup diagnostic flag Always
irga_motor_spd_f Motor speed diagnostic flag Always
irga_tec_tmpr_f Thermoelectric cooler (TEC) temperature diagnostic flag Always
irga_src_pwr_f Source power diagnostic flag Always
irga_src_tmpr_f Source temperature diagnostic flag Always
irga_src_curr_f Source current diagnostic flag Always
irga_off_f Gas head power down diagnostic flag Always
irga_sync_f Synchronization diagnostic flag Always
irga_cell_tmpr_f Cell temperature probe diagnostic flag Always
irga_cell_press_f Cell pressure diagnostic flag Always
irga_CO2_I_f CO2 I signal diagnostic flag Always
irga_CO2_Io_f CO2 I/O signal diagnostic flag Always
irga_H2O_I_f H2O I signal diagnostic flag Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 69
Table 7-9: Data fields in the Diagnostic output table
Data field name Description Data field included
irga_H2O_Io_f H2O I/O signal diagnostic flag Always
irga_CO2_Io_var_f CO2 I/O variation diagnostic flag Always
irga_H2O_Io_var_f H2 I/O variation diagnostic flag Always
irga_CO2_sig_strgth_f CO2 signal strength diagnostic flag Always
irga_H2O_sig_strgth_f H2O signal strength diagnostic flag Always
irga_cal_err_f Calibration file read error flag Always
irga_htr_ctrl_off_f Heater control off diagnostic flag Always
irga_diff_press_f Differential pressure out of bounds flag Always
CO2_sig_strgth CO2 signal strength (service sample cell when <80%; see EC155 CO2/H2O Closed-Path Gas Analyzermanual)
Always
H2O_sig_strgth H2O signal strength (service sample cell when <80%; see EC155 CO2/H2O Closed-Path Gas Analyzermanual)
Always
Table 7-10: Data fields in the EC100_Config_Notes output table
Data field name Units Description Data field included
config_type String String indicating why the EC100 was reconfigured Always
mode String String indicating sampling mode; see Sampling site, regime, and mode (p. 134)
If system is a CPEC310
site String String indicating sampling site; see Sampling site, regime, and mode (p. 134) for more details
If system is a CPEC310
bandwidth_freq Hz EC100 bandwidth (5, 10, 12.5, or 20 for 5 Hz, 10 Hz, 12.5 Hz, or 20 Hz, respectively)
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 70
Table 7-10: Data fields in the EC100_Config_Notes output table
Data field name Units Description Data field included
press_source
Sensor used by EC100 for ambient pressure (0 for EC100 basic barometer, 1 for user/custom barometer, 2 for EC100 enhanced barometer)
Always
diff_press_select
Parameter indicating whether to report ambient pressure (open- path system) or differential pressure (closed-path system); should be set to 2, which will auto-select
Always
sample_cell_press_type
Parameter indicating whether the sample cell pressure sensor is differential or absolute; set to 0 for EC155 gas head serial numbers <2000 and 1 for serial numbers 2000
Always
tmpr_source
Sensor used by EC100 for ambient temperature; set to 0 for EC100 temperature probe, no other values valid
Always
CO2_zero_coeff CO2 zero coefficient set from last CO2 zero
Always
CO2_span_coeff CO2 span coefficient set from last CO2 span
Always
CO2_span_mixra molmol-1 CO2mixing ratio of span gas Always
H2O_zero_coeff H2O zero coefficient set from last H2O zero
Always
H2O_span_coeff H2O span coefficient set from last H2O span
Always
H2O_span_T_DP deg C Dew point temperature of span gas Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 71
Table 7-10: Data fields in the EC100_Config_Notes output table
Data field name Units Description Data field included
EC155_pwr_off
Parameter indicating whether EC155 gas head is in sleep or power-down mode; set to 0 for power on and 1 for power off
Always
CR6_Volts V Battery voltage as measured at CR6 battery input terminal Always
Heater_volts V Voltage applied for EC155 heater Always
Shadow_corr Application of transducer shadowing correction; set to 0 for off and 1 for on
Always
Table 7-11: Data fields in the Flux_AmeriFluxFormat output table
Data field name Units Description Data field included
TIMESTAMP_START YYYYMMDDHHMM Start time of the averaging period Always
TIMESTAMP_END YYYYMMDDHHMM End time of the averaging period Always
CO2 molmol-1 CO2 flux after corrections Always
CO2_SIGMA molmol-1 Standard deviation of CO2
Always
H2O mmolmol-1 Average H2Omolar mixing ratio (dry basis) Always
H2O_SIGMA mmolmol-1 Standard deviation of H2O
Always
FC molm-2s-1 CO2 flux after corrections Always
FC_SSITC_TEST
Result of steady state and integral turbulence characteristics for FC according to Foken et al. (2004)
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 72
Table 7-11: Data fields in the Flux_AmeriFluxFormat output table
Data field name Units Description Data field included
LE Wm-2 Latent heat flux after corrections Always
LE_SSITC_TEST
Result of steady state and integral turbulence characteristics for LE according to Foken et al. (2004)
Always
ET mmhour-1 Evapotranspiration Always
ET_SSITC_TEST
Result of steady state and integral turbulence characteristics for ET according to Foken et al. (2004)
Always
H Wm-2 Sensible heat flux after corrections Always
H_SSITC_TEST
Result of steady state and integral turbulence characteristics for H according to Foken et al. (2004)
Always
G Wm-2 Calculated heat flux at the ground surface
If energy balance sensors are used
SG Wm-2 Change in heat storage in the soil above soil heat flux plates during averaging interval
If energy balance sensors are used
FETCH_MAX m
Distance upwind where the maximum contribution to footprint is found
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 73
Table 7-11: Data fields in the Flux_AmeriFluxFormat output table
Data field name Units Description Data field included
FETCH_90 m
Upwind distance that contains 90% of cumulative footprint; if NAN is returned, integration of the model never reached 90% within the allowable distance of integration
Always
FETCH_55 m Upwind distance that contains 55% of footprint Always
FETCH_40 m Upwind distance that contains 40% of footprint Always
WD decimal degrees Average wind direction Always
WS ms-1 Average wind speed Always
WS_MAX ms-1 Maximum wind speed Always
USTAR ms-1 Friction velocity Always
ZL Stability Always
TAU kgm-1s-2 Momentum flux Always
TAU_SSITC_TEST
Result of steady state and integral turbulence characteristics for TAU according to Foken et al. (2004)
Always
MO_LENGTH m Monin-Obukhov length Always
U ms-1 Average streamwise wind Always
U_SIGMA ms-1 Standard deviation of streamwise wind Always
V ms-1 Average crosswind Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 74
Table 7-11: Data fields in the Flux_AmeriFluxFormat output table
Data field name Units Description Data field included
V_SIGMA ms-1 Standard deviation of crosswind Always
W ms-1 Average vertical wind Always
W_SIGMA ms-1 Standard deviation of vertical wind Always
PA kPa Average atmospheric pressure Always
PA_SIGMA kPa Standard deviation of atmospheric pressure Always
TA_1_1_1 deg C
Average air temperature calculated from sonic temperature and H2O mixing ratio
Always
TA_SIGMA_1_1_1 deg C
Standard deviation of air temperature calculated from sonic temperature and H2Omixing ratio
Always
RH_1_1_1 %
Average relative humidity calculated from TA_1_1_1, H2O mixing ratio, and pressure
Always
T_DP_1_1_1 deg C
Average dew point temperature calculated from H2Omixing ratio and pressure
Always
TA_2_1_1 deg C Average air temperature measured by temp/RH probe
If temp/RH probe is used
RH_2_1_1 % Average relative humidity measured by temp/RH probe
If temp/RH probe is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 75
Table 7-11: Data fields in the Flux_AmeriFluxFormat output table
Data field name Units Description Data field included
T_DP_2_1_1 deg C
Average dew point temperature calculated from temp/RH probe measurements
If temp/RH probe is used
VPD hPa Vapor pressure deficit If temp/RH probe is used
T_SONIC deg C Average sonic temperature Always
T_SONIC_SIGMA deg C Standard deviation of sonic temperature Always
PBLH m Estimated planetary boundary layer height Always
SWC_x_1_1 %
Average volumetric soil water content; x is an index for the number of sensors
If CS650 or CS655 is used
TS_x_1_1 deg C
Average soil temperature; x is an index for the number of soil temperature measurements made
If TCAV or CS65X is used
ALB Albedo If SN500SS, NR01, or CNR4 is used
NETRAD Wm-2 Net radiation If SN500SS, NR01, or CNR4is used
PPFD_IN molm-2s-1 Photosynthetic photon density If CS310 is used
SW_IN Wm-2 Incoming short-wave radiation
If SN500SS, NR01, CNR4, CS301, or CS320 is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 76
Table 7-11: Data fields in the Flux_AmeriFluxFormat output table
Data field name Units Description Data field included
SW_OUT Wm-2 Outgoing short-wave radiation
If SN500SS, NR01, or CNR4 is used
LW_IN Wm-2 Incoming long-wave radiation
If SN500SS, NR01, or CNR4 is used
LW_OUT Wm-2 Outgoing long-wave radiation
If SN500SS, NR01, or CNR4 is used
P mm Precipitation in output interval If TE525 is used
T_CANOPY deg C Canopy temperature If SI-111 is used
Table 7-12: Data fields in the Flux_CSFormat output table
Data field name Units Description Data field included
FC molm-2s-1 Final corrected CO2 flux Always
FC_mass mgm-2s-1 Final corrected CO2 flux Always
FC_QC grade
Overall quality grade for Fc_molar and Fc_mass following Foken et al. (2012); see Quality grading (p. 151) for quality grade definitions
Always
FC_samples count Total number of time series samples used in calculation of Fc Always
LE Wm-2 Final corrected latent heat flux Always
LE_QC grade
Overall quality grade for LE following Foken et al. (2012); see Quality grading (p. 151) for quality grade definitions
Always
LE_samples count Total number of time series samples used in calculation of LE Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 77
Table 7-12: Data fields in the Flux_CSFormat output table
Data field name Units Description Data field included
H Wm-2 Final corrected sensible heat flux derived from sonic sensible heat flux
Always
H_QC grade
Overall quality grade for H following Foken et al. (2012); see Quality grading (p. 151) for quality grade definitions
Always
H_samples count Total number of time series samples used in calculation of H Always
H_FW Wm-2 Final corrected sensible heat flux derived from fine-wire thermocouple measurements
If FW05, FW1, or FW3 is used
H_FW_samples count Total number of time series samples used in calculation of H_FW
If FW05, FW1, or FW3 is used
NETRAD Wm-2 Average net radiation (corrected for wind)
If SN500SS, NR01, or CNR4 is used
G Wm-2 Heat flux at ground surface If energy balance sensors are used
SG Wm-2 Change in heat storage in the soil above the soil heat flux plates during the averaging interval
If energy balance sensors are used
energy_closure fraction Ratio of sensible and latent heat fluxes over surface heat flux plus net radiation
If energy balance sensors are used
poor_engr_clsur
If TRUE (non-0), energy closure is poor despite reasonably good micrometeorological conditions with no precipitation; alerts user to examine instruments
If energy balance sensors and rain gage are used
Bowen_ratio fraction Ratio of final sensible heat flux over final latent heat flux Always
TAU kgm-1s-2 Final corrected momentum flux Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 78
Table 7-12: Data fields in the Flux_CSFormat output table
Data field name Units Description Data field included
TAU_QC grade
Overall quality grade for TAU following Foken et al. (2012); see Quality grading (p. 151) for quality grade definitions
Always
USTAR ms-1 Friction velocity after coordinate rotations and frequency corrections Always
TSTAR deg C Scaling temperature after coordinate rotations, frequency corrections, and SND correction
Always
TKE m2s-2 Specific turbulence kinetic energy after coordinate rotations Always
TA_1_1_1 deg C Average ambient temperature calculated from sonic temperature and H2Omixing ratio
Always
TA_SIGMA_1_1_1 deg C Standard deviation of ambient temperature calculated from sonic temperature and H2Omixing ratio
Always
RH_1_1_1 deg C Relative humidity calculated from TA_1_1_1, H2Omixing ratio, and pressure
Always
T_DP_1_1_1 deg C Average dew point temperature calculated using H2Omixing ratio and ambient pressure
Always
e kPa Average water vapor pressure calculated using H2Omixing ratio and ambient pressure
Always
e_sat kPa Average saturated water vapor pressure calculated using TA_1_1_1 and ambient pressure
Always
TA_2_1_1 deg C Average ambient temperature measured by temp/RH probe
If temp/RH probe is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 79
Table 7-12: Data fields in the Flux_CSFormat output table
Data field name Units Description Data field included
RH_2_1_1 % Average relative humidity measured by temp/RH probe
If temp/RH probe is used
T_DP_2_1_1 deg C Average dew point temperature calculated using temp/RH probe measurements
If temp/RH probe is used
e_probe kPa Average water vapor pressure derived from temp/RH probe measurements
If temp/RH probe is used
e_sat_probe kPa Average saturated water vapor pressure derived from temp/RH probe measurements
If temp/RH probe is used
H2O_probe gm-3 Average water vapor density derived from temp/RH probe measurements
If temp/RH probe is used
PA kPa Average ambient air pressure Always
PA_SIGMA kPa Standard deviation of ambient air pressure Always
VPD kPa Average vapor pressure deficit Always
U ms-1 Mean streamwise wind speed after coordinate rotations Always
U_SIGMA ms-1 Standard deviation of streamwise wind after coordinate rotations Always
V ms-1 Average crosswind speed after coordinate rotations Always
V_SIGMA ms-1 Standard deviation of crosswind after coordinate rotations Always
W ms-1 Average vertical wind speed after coordinate rotations Always
W_SIGMA ms-1 Standard deviation of vertical wind after coordinate rotations Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 80
Table 7-12: Data fields in the Flux_CSFormat output table
Data field name Units Description Data field included
T_SONIC deg C Average sonic temperature Always
T_SONIC_SIGMA deg C Standard deviation of sonic temperature Always
sonic_azimuth decimal degrees
Compass direction in which the sonic negative x-axis points Always
WS ms-1 Average wind speed Always
WS_RSLT ms-1 Average horizontal wind speed Always
WD_SONIC decimal degrees
Average wind direction in the sonic coordinate system Always
WD_SIGMA decimal degrees
Standard deviation of wind direction in the sonic coordinate system
Always
WD decimal degrees Average compass wind direction Always
WS_MAX ms-1 Maximum wind speed Always
CO2 molmol-1 Average CO2 dry molar mixing ratio Always
CO2_SIGMA molmol-1 Standard deviation of CO2 dry molar mixing ratio Always
CO2_density mgm-3 Average CO2mass density Always
CO2_density_SIGMA mgm-3 Standard deviation of CO2mass density Always
H2O mmolmol-1 Average H2O dry molar mixing ratio Always
H2O_SIGMA mmolmol-1 Standard deviation of H2O dry molar mixing ratio Always
H2O_density mmolmol-1 Water vapor mass density Always
H2O_density_SIGMA mmolmol-1 Standard deviation of water vapor mass density Always
CO2_sig_strgth_Min Minimum CO2 signal strength Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 81
Table 7-12: Data fields in the Flux_CSFormat output table
Data field name Units Description Data field included
H2O_sig_strgth_Min Minimum H2O signal strength Always
FW deg C Average fine-wire thermocouple temperature
If FW05, FW1, or FW3 is used
FW_SIGMA deg C Standard deviation of fine-wire thermocouple temperature
If FW05, FW1, or FW3 is used
P mm Total precipitation If TE525MM is used
NETRAD Wm-2 Average net radiation (raw, not corrected for wind)
If net radiometer is used
ALB Average albedo If SN500SS, CNR4, or NR01 is used
SW_IN Wm-2 Average incoming short-wave radiation
If SN500SS, CNR4, CS301, CS320, or NR01 is used
SW_OUT Wm-2 Average outgoing short-wave radiation
If SN500SS, CNR4, or NR01 is used
LW_IN Wm-2 Average incoming long-wave radiation
If SN500SS, CNR4, or NR01 is used
LW_OUT Wm-2 Average outgoing long-wave radiation
If SN500SS, CNR4, or NR01 is used
T_nr K Average sensor body temperature If CNR4 or NR01 is used
T_nr_in K Average sensor body temperature for pyrgeometer measuring LW_IN If SN500SS is used
T_nr_out K Average sensor body temperature for pyrgeometer measuring LW_ OUT
If SN500SS is used
R_LW_in_meas Wm-2 Average raw incoming long-wave radiation
If CNR4 or NR01 is used
R_LW_out_meas Wm-2 Average raw outgoing long-wave radiation
If CNR4 or NR01 is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 82
Table 7-12: Data fields in the Flux_CSFormat output table
Data field name Units Description Data field included
PPFD_IN mols-1m-2 Average density of photosynthetic active radiation If CS310 is used
sun_azimuth decimal degrees Solar azimuth Always
sun_elevation decimal degrees Solar elevation Always
hour_angle decimal degrees Solar hour angle Always
sun_declination decimal degrees Solar declination Always
air_mass_coeff Air mass coefficient; ratio of the path length between the current solar position to solar noon
Always
daytime fraction Day time in fraction of an output interval Always
T_CANOPY deg C Average temperature of targeted object If SI-111 is used
T_SI111_body deg C Average temperature of sensor body If SI-111 is used
TS_x_1_1 deg C Average soil temperature for each soil temperature sensor; x is an index for the number of sensors
If TCAV or CS650 or CS655 is used
SWC_x_1_1 m3m-3 Average volumetric soil water content for each CS650 or CS655; x is an index for the number of each sensor model above
If CS650 or CS655 is used
CS65x_ec_x_1_1 dSm-1 Average electrical conductivity for each CS650 or CS655 sensor; x is an index for the number of sensors
If CS650 or CS655 is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 83
Table 7-12: Data fields in the Flux_CSFormat output table
Data field name Units Description Data field included
G_PLATE_x_1_1 Wm-2 Average heat flux through plate; x is an index for the number of HFP01 or HFP01SC
If HFP01 or HFP01SC is used
G_x_1_1 Wm-2 Soil heat flux at ground surface; x is an index for the number of soil sensor sets
If HFP01 or HFP01SC and CS65X are used
SG_x_1_1 Wm-2 Change in soil heat storage; x is an index for the number of soil sensor sets
If HFP01 or HFP01SC and CS65X are used
FETCH_MAX m Distance upwind where the maximum contribution to footprint is found
Always
FETCH_90 m
Upwind distance that contains 90% of cumulative footprint; if NAN is returned, integration of the model never reached 90% within the allowable distance of integration
Always
FETCH_55 m Upwind distance that contains 55% of footprint Always
FETCH_40 m Upwind distance that contains 40% of footprint Always
UPWND_DIST_INTRST m Upwind distance of interest for the average wind direction Always
FTPRNT_DIST_INTRST % Percentage of footprint from within the upwind range of interest Always
FTPRNT_EQUATION text
Returns either Kljun or KormannMeixner; the model of Kljun et al. (2004) is used for applicable atmospheric conditions, else the model of Kormann & Meixner (2001) is used
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 84
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
Ux ms-1 Average Ux Always
Ux_SIGMA ms-1 Standard deviation of Ux Always
Uy ms-1 Average Uy Always
Uy_SIGMA ms-1 Standard deviation of Uy Always
Uz ms-1 Average Uz Always
Uz_SIGMA ms-1 Standard deviation of Uz Always
UxUy_cov m2s-2 Covariance of Ux and Uy Always
UxUz_cov m2s-2 Covariance of Ux and Uz Always
UyUz_cov m2s-2 Covariance of Uy and Uz Always
TsUx_cov deg Cms-1 Covariance of Ts and Ux Always
TsUy_cov deg Cms-1 Covariance of Ts and Uy Always
TsUz_cov deg Cms-1 Covariance of Ts and Uz Always
USTAR_R ms-1 Friction velocity after coordinate rotations Always
UV_cov ms-1 Covariance of streamwise wind and crosswind after coordinate rotations
Always
UW_cov ms-1 Covariance of streamwise wind and vertical wind after coordinate rotations
Always
VW_cov ms-1 Covariance of crosswind and vertical wind after coordinate rotations
Always
UT_SONIC_Cov mdeg Cs-1 Covariance of streamwise wind and sonic temperature after coordinate rotations
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 85
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
VT_SONIC_Cov mdeg Cs-1 Covariance of crosswind and sonic temperature after coordinate rotations
Always
WT_SONIC_Cov mdeg Cs-1 Covariance of vertical wind and sonic temperature after coordinate rotations
Always
UW_Cov_fc m2s-2 Covariance of streamwise wind and vertical wind after coordinate rotations and frequency corrections
Always
VW_Cov_fc m2s-2 Covariance of crosswind and vertical wind after coordinate rotations and frequency corrections
Always
WT_SONIC_Cov_fc mdeg Cs-1 Covariance of vertical wind and sonic temperature after coordinate rotations and frequency corrections
Always
WT_SONIC_Covfc_SND mdeg Cs-1
Covariance of vertical wind and sonic temperature after coordinate rotations, frequency corrections, and SND correction
Always
sonic_samples count Number of raw sonic samples in averaging period without diagnostic flags
Always
no_sonic_head_Tot count Number of sonic samples where no sonic head was detected
Always
no_new_sonic_data_Tot count Number of scans where no sonic data was received Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 86
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
sonic_amp_l_f_Tot count Number of sonic samples with amplitude low diagnostic flag
Always
sonic_amp_h_f_Tot count Number of sonic samples with amplitude high diagnostic flag
Always
sonic_sig_lck_f_Tot count Number of sonic samples with signal lock diagnostic flag
Always
sonic_del_T_f_Tot count Number of sonic samples with delta temperature diagnostic flag
Always
sonic_aq_sig_f_Tot count Number of sonic samples with acquiring signal diagnostic flag
Always
sonic_cal_err_f_Tot count Number of sonic samples with calibration error diagnostic flag
Always
CSAT3H_user_ctrl_on_Tot count Number of times CSAT3H_ user_ctrl_on from data logger to heater controller
If CSAT3AH is used
CSAT3H_ctrl_on_Tot count Number of times CSAT3H_ ctrl_on in the heater controller itself
If CSAT3AH is used
T_trnsd_uppr deg C Average temperature of top transducer If CSAT3AH is used
T_trnsd_uppr_Min deg C Minimum temperature of top transducer If CSAT3AH is used
T_trnsd_lwr deg C Average temperature of lower transducer If CSAT3AH is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 87
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
T_trnsd_lwr_Min deg C Minimum temperature of lower transducer If CSAT3AH is used
pwr_trnsd_Max W Power used by heating transducers If CSAT3AH is used
trnsd_heater_secs s Number of seconds in the interval that transducer was heating
If CSAT3AH is used
trnsd_heater_fail_Tot count Number of transducer heater failures If CSAT3AH is used
T_arm_uppr deg C Average temperature of upper arm If CSAT3AH is used
T_arm_uppr_Min deg C Minimum temperature of upper arm If CSAT3AH is used
T_arm_lwr deg C Average temperature of lower arm If CSAT3AH is used
T_arm_lwr_Min deg C Minimum temperature of lower arm If CSAT3AH is used
pwr_arms_Max W Power used by heating arms If CSAT3AH is used
arm_heater_secs s Number of seconds in the interval that arms were heating
If CSAT3AH is used
arm_heater_fail_Tot count Number of arm heater failures If CSAT3AH is used
pwr_hr_trnsds_arms W Hourly power used by arms and transducers If CSAT3AH is used
trnsd_ice_wet_lck s
Number of seconds in the interval that sonic transducer was locked due to ice and wet
If CSAT3AH is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 88
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
heating_inaplcbl_f_Tot count
Number of flags indicating sonic heating would be inapplicable to improve measurements
If CSAT3AH is used
T_amb_ctrl deg C Average ambient air temperature of controller If CSAT3AH is used
T_amb_ctrl_Min deg C Minimum ambient air temperature of controller If CSAT3AH is used
RH_amb_ctrl_Max % Maximum ambient relative humidity of controller If CSAT3AH is used
T_DP_amb_ctrl_Max deg C Average ambient dew point temperature of controller If CSAT3AH is used
com_rslt_get_Tot count Number of successes in getting data from CR300 If CSAT3AH is used
com_rslt_snt_Tot count Number of successes in sending data to CR300 If CSAT3AH is used
UxCO2_Cov mgm-2s-1 Covariance of Ux and CO2 density Always
UyCO2_Cov mgm-2s-1 Covariance of Uy and CO2 density Always
UzCO2_Cov mgm-2s-1 Covariance of Uz and CO2 density Always
UxH2O_Cov gm-2s-1 Covariance of Ux and water vapor density Always
UyH2O_Cov gm-2s-1 Covariance of Uy and water vapor density Always
UzH2O_Cov gm-2s-1 Covariance of Uz and water vapor density Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 89
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
UCO2_Cov mgm-2s-1 Covariance of streamwise wind and CO2 density after coordinate rotations
Always
VCO2_Cov mgm-2s-1 Covariance of crosswind and CO2 density after coordinate rotations
Always
WCO2_Cov mgm-2s-1 Covariance of vertical wind and CO2 density after coordinate rotations
Always
UH2O_Cov gm-2s-1 Covariance of streamwise wind and H2O density after coordinate rotations
Always
VH2O_Cov gm-2s-1 Covariance of crosswind and H2O density after coordinate rotations
Always
WH2O_Cov gm-2s-1 Covariance of vertical wind and H2O density after coordinate rotations
Always
WCO2_Cov_fc mgm-2s-1 Covariance of vertical wind and CO2 density after coordinate rotations and frequency corrections
Always
WH2O_Cov_fc gm-2s-1 Covariance of vertical wind and H2O density after coordinate rotations and frequency corrections
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 90
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
CO2_samples count
Number of CO2 samples without diagnostic flags, within threshold for CO2 signal strength (set in code to default of 0.7), and within factory calibrated CO2 measurement range (0 to 1000 molmol-1)
Always
H2O_samples count
Number of H2O samples without diagnostic flags, within threshold for H2O signal strength (set in code to default of 0.7), and within factory calibrated H2O measurement range (0 to 72 mmolmol-1)
Always
no_irga_head_Tot count Number of samples where no gas analyzer head was detected
Always
no_new_irga_data_Tot count Number of scans where no gas analyzer data was received
Always
irga_bad_data_f_Tot count Number of IRGA samples with any IRGA diagnostic flag set high
Always
irga_gen_fault_f_Tot count Number of gas analyzer samples with general system fault diagnostic flag
Always
irga_startup_f_Tot count Number of gas analyzer samples with startup diagnostic flag
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 91
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
irga_motor_spd_f_Tot count Number of gas analyzer samples with motor speed diagnostic flag
Always
irga_tec_tmpr_f_Tot count Number of gas analyzer samples with TEC temperature diagnostic flag
Always
irga_src_pwr_f_Tot count Number of gas analyzer samples with source power diagnostic flag
Always
irga_src_tmpr_f_Tot count Number of gas analyzer samples with source temperature diagnostic flag
Always
irga_src_curr_f_Tot count Number of gas analyzer samples with source current diagnostic flag
Always
irga_off_f_Tot count Number of gas analyzer samples with gas head power down diagnostic flag
Always
irga_sync_f_Tot count
Number of gas analyzer samples with synchronization diagnostic flag
Always
irga_amb_tmpr_f_Tot count
Number of gas analyzer samples with ambient temperature probe diagnostic flag
Always
irga_amb_press_f_Tot count Number of gas analyzer samples with ambient pressure diagnostic flag
Always
irga_CO2_I_f_Tot count Number of gas analyzer samples with CO2 I signal diagnostic flag
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 92
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
irga_CO2_Io_f_Tot count Number of gas analyzer samples with CO2 I/O signal diagnostic flag
Always
irga_H2O_I_f_Tot count Number of gas analyzer samples with H2O I signal diagnostic flag
Always
irga_H2O_Io_f_Tot count Number of gas analyzer samples with H2O I/O signal diagnostic flag
Always
irga_CO2_Io_var_f_Tot count Number of gas analyzer samples with CO2 I/O variation diagnostic flag
Always
irga_H2O_Io_var_f_Tot count Number of gas analyzer samples with H2O I/O variation diagnostic flag
Always
irga_CO2_sig_strgth_f_Tot count Number of gas analyzer samples with CO2 signal strength diagnostic flag
Always
irga_H2O_sig_strgth_f_Tot count Number of gas analyzer samples with H2O signal strength diagnostic flag
Always
irga_cal_err_f_Tot count Number of gas analyzer samples with calibration file read error flag
Always
irga_htr_ctrl_off_f_Tot count Number of gas analyzer samples with heater control off diagnostic flag
Always
irga_diff_press_f_Tot count
Number of gas analyzer samples with differential pressure out of range diagnostic flag
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 93
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
UxFW_cov deg Cms-1 Covariance of Ux and fine- wire thermocouple temperature
If FW05, FW1, or FW3 is used
UyFW_cov deg Cms-1 Covariance of Uy and fine- wire thermocouple temperature
If FW05, FW1, or FW3 is used
UzFW_cov deg Cms-1 Covariance of Uz and fine- wire thermocouple temperature
If FW05, FW1, or FW3 is used
UFW_cov deg Cms-1 Covariance of streamwise wind and fine-wire thermocouple temperature after coordinate rotations
If FW05, FW1, or FW3 is used
VFW_cov deg Cms-1 Covariance of crosswind and fine-wire thermocouple temperature after coordinate rotations
If FW05, FW1, or FW3 is used
WFW_cov deg Cms-1 Covariance of vertical wind and fine-wire thermocouple temperature after coordinate rotations
If FW05, FW1, or FW3 is used
WFW_cov_fc deg Cms-1
Covariance of vertical wind and fine-wire thermocouple temperature after coordinate rotations and frequency corrections
If FW05, FW1, or FW3 is used
FW_samples count
Number of valid fine-wire thermocouple measurements in the averaging period from which covariances may be calculated
If FW05, FW1, or FW3 is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 94
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
pump_tmpr deg C Average pump temperature Always
pump_press kPa Average pump pressure Always, but data is excluded during CO2
or H2O span
pump_flow_duty_cycle Adimensional Average pump duty cycle (0is off and 1 is full power)
Always, but data is excluded during CO2
or H2O span
pump_flow_set_pt kPa Pressure set point of sample cell Always
pump_heater_secs s Number of seconds in the interval that pump heater was on
Always
pump_fan_secs s Number of seconds in the interval that pump fan was on
Always
valve_tmpr deg C Average temperature of valve module
If CPEC310 with valve module is used
valve_heater_secs s Number of seconds in the interval that valve module heater was on
If CPEC310 with valve module is used
valve_fan_secs s Number of seconds in the interval valve module fan was on
If CPEC310 with valve module is used
scrub_tmpr deg C Average temperature of scrub module
If scrub module is used
scrub_press kPa Average pressure of scrub module
If scrub module is used
scrub_heater_secs s Number of seconds in the interval that scrub module heater was on
If scrub module is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 95
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
scrub_fan_secs s Number of seconds in the interval that scrub module fan was on
If scrub module is used
cell_tmpr deg C Average temperature of sample cell Always
cell_tmpr_SIGMA deg C Standard deviation of sample cell temperature Always
cell_press kPa Average pressure inside sample cell Always
cell_press_SIGMA kPa Standard deviation of sample cell pressure Always
diff_press kPa
Differential pressure (the difference in pressure between sample cell and ambient)
Always
pump_flow Lmin-1 Average volumetric flow to pump (sum of sample flow and vortex bypass flow)
Always
pump_flow_SIGMA Lmin-1 Standard deviation of pump flow Always
cell_e kPa Average vapor pressure in sample cell Always
cell_T_DP deg C Average dew point temperature inside sample cell
Always
cell_e_sat kPa Average saturation vapor pressure inside sample cell Always
cell_RH % Average relative humidity inside sample cell Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 96
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
alpha decimal degrees
Alpha angle used for coordinate rotations (regardless of planar fit or double rotation method, the angle convention of Wilczak, Oncley, and Stage [2001] is used)
Always
beta decimal degrees
Beta angle used for coordinate rotations (regardless of planar fit or double rotation method, the angle convention of Wilczak, Oncley, and Stage [2001] is used)
Always
gamma decimal degrees
Gamma angle used for coordinate rotations (regardless of planar fit or double rotation method, the angle convention of Wilczak, Oncley, and Stage [2001] is used)
Always
height_measurement m User-entered measurement height of eddy-covariance sensors
Always
height_canopy m User-entered canopy height Always
surface_type_text text User-entered surface type Always
displacement_user m User-entered displacement height; 0 for auto calculation Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 97
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
d m
Displacement height used in calculations (this will be equal to displacement_user if user entered a non-0 value; if displacement_user is 0, program will auto calculate)
Always
roughness_user m User-entered roughness length; 0 for calculation Always
z0 m
Roughness length used in calculations (this will be equal to roughness_user if user entered a non-0 value; if roughness_user is 0, program will auto calculate)
Always
z m Aerodynamic height Always
MO_LENGTH m Monin-Obukhov length Always
ZL mm-1 Atmospheric surface layer stability Always
iteration_FreqFactor count
Number of iterations for recalculating Monin- Obukhov length and frequency factors
Always
latitude decimal degrees
Latitude; positive for northern hemisphere, negative for southern hemisphere
Always
longitude decimal degrees
Longitude; positive for eastern hemisphere, negative for western hemisphere
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 98
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
altitude m Number of meters above sea level at the site Always
UTC_offset hr
Time offset in hours between the site local standard time and UTC/GMT
Always
separation_x_irga m
Separation between sonic anemometer and gas analyzer with respect to sonic x-axis
Always
separation_y_irga m
Separation between sonic anemometer and gas analyzer with respect to sonic y-axis
Always
separation_lat_dist_irga m
Separation distance between sonic anemometer and gas analyzer along the axis perpendicular to oncoming wind
Always
separation_lag_dist_irga m
Separation distance between sonic anemometer and gas analyzer along the axis parallel to oncoming wind
Always
separation_lag_scan_irga scans
Number of scans to lag gas analyzer data relative to sonic anemometer data to account for separation along the axis of oncoming wind and wind velocity
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 99
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
separation_x_FW m
Separation between sonic anemometer and fine-wire thermocouple with respect to sonic x-axis
If FW05, FW1, or FW3 is used
separation_y_FW m
Separation between sonic anemometer and fine-wire thermocouple with respect to sonic anemometer y-axis
If FW05, FW1, or FW3 is used
FW_diameter m Effective diameter of fine- wire thermocouple junction
If FW05, FW1, or FW3 is used
separation_lat_dist_FW m
Separation distance between sonic anemometer and fine-wire thermocouple along axis perpendicular to oncoming wind
If FW05, FW1, or FW3 is used
separation_lag_dist_FW m
Separation distance between sonic anemometer and fine-wire thermocouple along axis parallel to oncoming wind
If FW05, FW1, or FW3 is used
separation_lag_scan_FW scans
Number of scans to lag fine- wire thermocouple data relative to sonic anemometer data to account for separation along axis of oncoming wind and wind velocity
If FW05, FW1, or FW3 is used
time_const_FW m Calculated time constant of fine-wire thermocouple
If FW05, FW1, or FW3 is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 100
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
MAX_LAG scans
Maximum number of scans to lag gas analyzer or fine- wire thermocouple data with respect to sonic anemometer data when doing cross correlation for covariance maximization (for example, if MAX_LAG = 2, the program will consider lags of 2, 1, 0, +1, and +2)
Always
lag_CO2 scans
Lag applied to CO2 data with respect to sonic anemometer data that maximizes covariance
Always
lag_H2O scans
Lag applied to H2O data with respect to sonic anemometer data that maximizes covariance
Always
lag_FW scans
Lag applied to fine-wire thermocouple data with respect to sonic anemometer data that maximizes covariance
Always
FreqFactor_UW_VW number Frequency correction factor applied to momentum fluxes
Always
FreqFactor_WT_SONIC number Frequency correction factor applied to wTs covariance Always
FreqFactor_WCO2 number Frequency correction factor applied to wCO2 covariance
Always
FreqFactor_WH2O number Frequency correction factor applied to wH2O covariance
Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 101
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
FreqFactor_WFW number
Frequency correction factor applied to fine-wire thermocouple derived wFW covariance
Always
rho_d gm-3 Average density of dry air calculated from eddy- covariance sensors
Always
rho_a kgm-3 Average density of ambient moist air calculated from eddy-covariance sensors
Always
rho_d_probe gm-3 Average density of dry air calculated from temp/RH probe measurements
If temp/RH probe is used
rho_a_probe kgm-3 Average density of ambient moist air calculated from temp/RH probe measurements
If temp/RH probe is used
Cp Jkg-1K-1 Specific heat of ambient moist air at constant pressure
Always
Lv Jg-1 Latent heat of vaporization Always
T_panel deg C Average temperature of data logger wiring panel Always
T_panel_CDM_VOLT_x deg C
Average panel temperature of VOLT 116, where x at the end of the name is an index from 1 to 4, representing each of the thermistors under the terminal strips of the VOLT 116
If VOLT 116 is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 102
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
nr01_heater_secs s Number of seconds in the averaging interval that NR01 heater was enabled
If NR01 is used
cnr4_fan_secs s Number of seconds in the averaging interval that CNR4 fan was enabled
If CNF4 with CNR4 is used
cnr4_heater_1_secs s
Number of seconds in the averaging interval that CNR4 heater #1 was enabled
If CNF4 with CNR4 is used
cnr4_heater_2_secs s
Number of seconds in the averaging interval that CNR4 heater #2 was enabled
If CNF4 with CNR4 is used
sn500_heater_secs s
Number of seconds in the averaging interval that SN500SS heater was enabled
If SN500SS is used
V_CS320 mV Output voltage from CS320 If CS320 is used
T_CS320 deg C Body temperature of CS320 If CS320 is used
x_incline decimal degrees
Pyranometer incline relative to its x-axis If CS320 is used
y_incline decimal degrees
Pyranometer incline relative to its y-axis If CS320 is used
z_incline decimal degrees
Pyranometer incline relative to its z-axis If CS320 is used
CPEC306/310 Closed-Path Eddy-Covariance Systems 103
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
shfp_cal_x_1_1 Wm-2mV-1
Calibrated multiplier for heat flux plate (if HFP01 is used, this value is 1,000 divided by the sensitivity as reported in the calibration sheet; if HFP01SC is used, this is determined from self- calibration), where x is an index for the number of sensors
If HFP01 or HFP01SC is used
shfp_cal_fail_x_1_1 text
Reads TRUE if any readings from HFP01SC were not valid (NAN) or if calibrated sensitivity was <80% or >105% of the nominal sensitivity reported on the sensor calibration sheet (x is an index for the number of sensors)
If HFP01SC is used
batt_volt volt Average battery voltage supplying power to data logger
Always
slowsequence_Tot count
Number of slow sequences during averaging interval (for example, the number of times biomet and energy balance sensors were measured)
Always
process_time ms Average processing time for each scan Always
process_time_SIGMA ms Standard deviation of scan time Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 104
Table 7-13: Data fields in the Flux_Notes output table
Data field name Units Description Data field included
process_time_Max ms Maximum processing time for a scan Always
process_time_Min ms Minimum processing time for a scan Always
buff_depth number Average number of records stored in buffer Always
buff_depth_Max number Maximum number of records stored in buffer Always
Table 7-14: Data fields in the ZeroSpan_Check_Notes data output table
Data field name Units Description Data field included
check adimensional
String indicating to which type of zero or span the record corresponds (possible types: zero, CO2Span, H2OSpan)
Always
drifted_f Boolean
Reads TRUE if the zero or span measurement drifted beyond a 95% probability of its being within a normal distribution of the expected value
Always
CO2_reference molmol-1 CO2mixing ratio of reference gas during zero or span check Always
CO2 molmol-1 Measured CO2mixing ratio during zero or span check Always
H2O_reference mmolmol-1 H2Omixing ratio of reference gas during zero or span check Always
H2O mmolmol-1 Measured H2Omixing ratio during zero or span check Always
cell_tmp deg C Sample cell temperature during zero or span check Always
CPEC306/310 Closed-Path Eddy-Covariance Systems 105
Table 7-14: Data fields in the ZeroSpan_Check_Notes data output table
Data field name Units Description Data field included
cell_press kPa Sample cell pressure during zero or span check Always
diff_press kPa Differential pressure between ambient and sample cell during zero or span check
Always
valv_press_offset kPa Offset in differential pressure measured while pump is off Always
Td_reference deg C Dew point temperature of reference gas during zero or span check
Always
Cell_T_DP deg C Dew point temperature inside sample cell during zero or span check
Always
valve_flow Lmin-1 Mean flow during zero or span check Always
valve_flow_set Lmin-1 Set point for flow during zero or span check Always
scrub_press kPa Scrub module gauge pressure during zero
If scrub module is used
CO2_sig_strgth_zero adimensional CO2 signal strength during zero Always
H2O_sig_strgth_zero adimensional H2O signal strength during zero Always
valve_tmpr_ok Boolean Reads TRUE if valve module temperature is within operating range
If CPEC310 is used
scrub_tmpr_ok Boolean Reads TRUE if scrub module temperature is within operating range
If CPEC310 and scrub module are
used
CPEC306/310 Closed-Path Eddy-Covariance Systems 106
Table 7-15: Data fields in the System_Operatn_Notes data output table
Data field name Units Description Data field included
Message Text string Message describing a change of system status Always
Current value Text string Additional information corresponding to Message Always
Previous value Text String Additional information corresponding to Message Always
7.6 Program sequence of measurement and corrections The main correction procedures and algorithms implemented into the program are included in the following numbered list. For more information on the sequence of measurements and corrections, refer to EasyFlux DL CR6CP process flow (p. 125).
1. Despike and filter raw time series data using sonic anemometer and gas analyzer diagnostic codes and signal strength and measurement output range thresholds.
2. Coordinate rotations with an option to use the double rotation method (Tanner and Thurtell 1969) or planar fit method (Wilczak, Oncley, and Stage 2001).
3. Lag CO2 and H2Omeasurements relative to sonic wind measurements for maximization of CO2 and H2O covariances (Horst and Lenschow 2009; Foken et al. 2012), with additional constraints to ensure lags are physically possible.
4. Frequency corrections using commonly used cospectra (Moore 1986; van Dijk 2002a; Moncrieff et al. 1997) and transfer functions of block averaging (Kaimal, Clifford, and Lataitis 1989), line/volume averaging (Moore 1986; Moncrieff et al. 1997; Foken et al. 2012; van Dijk 2002a), time constants (Montgomery 1947; Shapland et al. 2014; Geankoplis 1993), sensor separation (Horst and Lenschow 2009; Foken et al. 2012), and tube attenuation (Ibrom et al. 2007; Burgon et al. 2015).
5. A modified SND correction (Schotanus, Nieuwstadt, and de Bruin 1983) to derive sensible heat flux from sonic sensible heat flux following the implementation as outlined in van Dijk (2002b). Additionally, fully corrected real sensible heat flux computed from fine-wire thermometry to be provided.
CPEC306/310 Closed-Path Eddy-Covariance Systems 107
6. Data quality qualifications based on steady state conditions, surface-layer turbulence characteristics, and wind directions following Foken et al. (2012) for the Flux_CSFormat output table or Foken et al. (2004) for the Flux_AmeriFluxFormat output table.
7. If energy balance sensors are used, calculation of energy closure based on energy balance measurements and corrected sensible and latent heat fluxes.
8. Footprint characteristics are computed using Kljun et al. (2004) and Kormann and Meixner (2001).
NOTE: The appendices in the EasyFlux DL CR6OP or CR1KXOPmanual describe the implementation of the major corrections in EasyFlux DL CR6CP, with the exception of frequency correction for tube attenuation, which is described in Ibrom et al. (2007), Burgon et al. (2015), and the code itself. It should also be noted that the appendix on WPL density corrections for open-path is not applicable here, since the closed-path analyzer gas concentrations are output as dry molar mixing ratios.
8. Zero and span Since a CPEC310 system includes a valve module, it may be configured to self-initiate an automatic zero and span of the EC155 gas analyzer. The timing, whether the system will simply check the drift or actually set new zero/span coefficients, and whether the automatic zero/span will include an H2O span, are all determined by user-entered constants relating to a CPEC310 (see constants that are indented under the constant CPEC310 in Table 7-1 [p. 39]). An automatic zero-and-span cycle on a CPEC310 may be manually initiated at any time; instructions to do so are found in User-initiated zero/span for CPEC310 (p. 115).
For CPEC310 systems that are not set up with a continuously available source of H2O span gas, which is typically the case, H2O spans must be manually set up and initiated by the user. More details are found in CPEC310 manual H2O span (p. 118).
CPEC306 systems require the user to manually set up and initiate the zero, CO2 span, and/or H2O span, since these systems do not include a valve module. More details are found under User- initiated manual zero/span for CPEC306 (p. 119).
Regardless of system type, performing a user-initiated zero or span is most easily done using the CR1000KD keypad. This requires connecting a CR1000KD to the CS I/O port of the CR6 data logger and initiating the process while the program is running. Press Enter twice to access the main menu, then use the keypad down arrow to scroll to the submenu Attendant Zero/Span.
CPEC306/310 Closed-Path Eddy-Covariance Systems 108
Highlight and press Enter. This menu accesses all menus and variables needed for doing a zero and span as explained in the following sections.
NOTE: If a tall tower installation requires the CR6 to be far away from the EC155 gas analyzer, making it inconvenient to access the CR1000KD, it may be more practical to use a laptop running ECMon software to set the zero and spans, as explained in the EC155 CO2/H2O Closed-Path Gas Analyzermanual.
For reference, Figure 7-2 (p. 49) shows an organizational schematic for all the keypad menus. To return to a previous menu at any time, press Esc.
NOTE: Table 8-1 (p. 110) lists the variables found within the Attendant Zero/Span menu and its submenus. The table also shows the equivalent variable names in the data logger public table. If a CR1000KD is not available, performing a zero/span may alternatively be done from LoggerNet software by using the Connect Screen to create a numeric display that includes all the variables in Table 8-1 (p. 110). Follow the instructions in the sections above, substituting public table variable names (last column in Table 8-1 [p. 110]) for the variable names in the menus (first colum in Table 8-1 [p. 110]).
NOTE: Aliases have been used for public variables found in the zero and span menus in order to make the meanings of the variable more readily understood or to shorten the length of the variable names so they fit on the keypad display screen.
CPEC306/310 Closed-Path Eddy-Covariance Systems 109
Table 8-1: Variables found in menus for zero and span
Variable name Default Description
Name of variable in Public table
(if no CR1000KD is available)
Valv Tmpr Ctrl or Valv/Scrub Tmpr Ctrl
Valv T Ok
A TRUE/FALSE read-only variable. It must read TRUE to perform an auto zero/span; if FALSE, the valve module temperature is not within its operating range, and Val T Ctl On should be set to TRUE to bring the temperature within range. (Omitted if the system is a CPEC306.)
valve_tmpr_ok
Valv T
A read-only variable showing the temperature in C of the valve module. (Omitted if the system is a CPEC306.)
valve_tmpr
Scrb T Ok
A TRUE/FALSE read-only variable. It must read TRUE to perform an auto zero using scrub module as the zero gas source; if FALSE, scrub module temperature is not within its operating range, and V/S T Ctl On should be set to TRUE to bring the temperature within range. (Omitted if system lacks a scrub module.)
scrub_tmpr_ok
Scrb T
A read-only variable showing the temperature in C of scrub module. (Omitted if the system lacks a scrub module.)
scrub_tmpr
CPEC306/310 Closed-Path Eddy-Covariance Systems 110
Table 8-1: Variables found in menus for zero and span
Variable name Default Description
Name of variable in Public table
(if no CR1000KD is available)
Val T Ctl On (or V/S T Ctl On if scrub module is included)
FALSE
Set to TRUE to enable temperature control (heaters and fans) of valve module (and scrub module, if applicable). Following an auto zero/span, this variable may be set back to FALSE to conserve power.
valve_tmpr_ctrl_ flg
Prfrm Field Zero, Prfrm Field CO2 Span, or Prfrm Field H2O Span
Chk_Set_Optn (only if CPEC310
is used)
Set to CHK_OLY to perform a field zero check without changing zero coefficients; set to CHK_SET to perform a field zero check and set new zero coefficients.
attndnt_chck_ set_option
Pick ZRO_ALL Pick SPN_CO2 Pick SPN_H2O Pick AUTO_ZS (only if CPEC310
is used)
FLD_MEA
Indicates current sampling mode. Depending on which keypad menu is viewed, variable will be named to indicate which value to choose. For example, under the Prfrm AUTO_ZS cycle menu, the value of Pick AUTO_ZS should be changed from field measurements mode (FLD_ MEA) to AUTO_ZS to initiate auto zero/span cycle.
mode
Options: 1 = FLD_MEA 3 = ZRO_ALL 4 = SPN_CO2 5 = SPN_H2O 7 = AUTO_ZS
CPEC306/310 Closed-Path Eddy-Covariance Systems 111
Table 8-1: Variables found in menus for zero and span
Variable name Default Description
Name of variable in Public table
(if no CR1000KD is available)
Prfrm Field Zero, Prfrm Field CO2 Span, Prfrm
Field H2O Span, or Prfrm AUTO_
ZS cycle
Site (only if CPEC310
is used)
A read-only variable showing current sampling site. Monitor this variable to see progress of zero/span. (See Sampling site, regime, and mode [p. 134] for more details on sampling sites.)
site_
Options: 1 = fld smp 2 = offst P 3 = chk CO2 4 = chk zro 5 = set zro 6 = set CO2 7 = chk H2O 8 = set H2O 9 = equilib 10 = irg_off
Sec On Site (only if CPEC310
is used)
A read-only variable showing number of seconds the system has been on current site.
Sec_on_site
IRGA Error
A read-only variable showing the IRGA diagnostic word; a non-0 result indicates an error condition is detected. (For an interpretation of the IRGA diagnostic word, see Table D-1 [p. 150] in System diagnostic word [p. 150].)
irga_er
GasFlw L/min (only if CPEC310
is used)
A read-only variable showing the current flow in Lmin-1 through the sample cell.
Valve_flow
VALV T Error FALSE
A read-only variable showing a valve temperature outside of range; if TRUE, valve is <2 or >50 C.
valv_tmpr_er
CPEC306/310 Closed-Path Eddy-Covariance Systems 112
Table 8-1: Variables found in menus for zero and span
Variable name Default Description
Name of variable in Public table
(if no CR1000KD is available)
Prfrm Field Zero, Prfrm Field CO2 Span, or Prfrm Field H2O Span
Pump Off (only if CPEC306
is used) FALSE
A variable used to disable pump; pump should be disabled before conducting a manual zero or span.
Pump_off_flg
Prfrm Field Zero, Prfrm Field CO2 Span, or Prfrm AUTO_ZS cycle
CO2 umol/mol
A read-only variable showing the current measurement of CO2 inside the sample cell in molmol-1.
Sonic_irga_raw (6)
Prfrm Field Zero, Prfrm Field H2O Span, or Prfrm AUTO_ZS cycle
H2Ommol/mol
A read-only variable showing current measurement of H2O dry molar mixing ratio inside the sample cell in mmolmol-1.
Sonic_irga_raw (7)
Prfrm Field Zero or Prfrm AUTO_
ZS cycle
SCRB T Error (only if CPEC310
is used) FALSE
A read-only variable showing a scrub module temperature outside of range; if TRUE, scrub module is <5 or >50 C.
scrb_tmpr_er
Prfrm Field CO2 Span or Prfrm AUTO_ZS cycle
CO2 Spn Gas 400 Dry molar mixing ratio of CO2 span gas in molmol-1. CO2_span_gas
CPEC306/310 Closed-Path Eddy-Covariance Systems 113
Table 8-1: Variables found in menus for zero and span
Variable name Default Description
Name of variable in Public table
(if no CR1000KD is available)
Prfrm Field H2O Span or Prfrm AUTO_ZS cycle
H2O Spn T_DP (only if CPEC310
is used) 10
Dew point temperature setting on the H2O span gas source in C.
Td_span_gas
H2O Spn MX_R (only if CPEC310
is used)
A read-only variable showing the calculated dry molar mixing ratio of the H2O span gas in mmolmol-1. The air pressure difference between ambient and dew point generator is taken into account when calculating.
H2O_span_gas
Prfrm Field Zero Do Zero
(only if CPEC306 is used)
FALSE
Set to TRUE to manually zero the analyzer. (Zero gas should be flowing and Pump Off set to TRUE.)
do_zero_flg
Prfrm Field CO2 Span
Do CO2 Span (only if CPEC306
is used) FALSE
Set to TRUE to manually do a CO2 span of the analyzer. (CO2 span gas should be flowing and Pump Off set to TRUE.)
Do_CO2_span_ flg
Prfrm Field H2O Span
Do H2O Span (only if CPEC306
is used) FALSE
Set to TRUE to manually do an H2O span of the analyzer. (H2O span gas should be flowing and Pump Off set to TRUE.)
Do_H2O_span_ flg
T_DP_probe C Dew point temperature from temp/RH probe. (Omitted if system lacks temp/RH probe.)
T_DP_probe
CPEC306/310 Closed-Path Eddy-Covariance Systems 114
Table 8-1: Variables found in menus for zero and span
Variable name Default Description
Name of variable in Public table
(if no CR1000KD is available)
Prfrm AUTO_ZS cycle
Cell T_DP
A read-only variable showing current measurement of dew point temperature inside the sample cell in C.
cell_T_DP
VALV Flw Err FALSE
A read-only variable showing a valve flow error outside of the valve flow set point (default of 1.0 Lmin-1).
valv_flow_er
8.1 User-initiated zero/span for CPEC310 Before beginning a user-initiated zero/span, the temperature of the valve module (and scrub module, if applicable) must be within operating range. Select the submenu Valv Tmpr Ctrl (or Valv/Scrub Tmpr Ctrl if using a scrub module), found under the Attendant Zero/Span menu, by highlighting it and pressing Enter. The display will show some read-only values of the module temperature and whether it is within safe operating range. If the temperature is out of range, scroll down to Val T Ctl On (or V/S T Ctl On if using a scrub module), press Enter, highlight TRUE, and press Enter. This will enable the module temperature control. Continue to monitor the module temperature readings shown in this menu until they are within operating range.
NOTE: Upon completion of a zero/span in a CPEC310 system, navigate again to Val T Ctl On (or V/S T Ctl On if using scrub module) and set its value back to FALSE to save power.
8.1.1 CPEC310 auto zero/span To initiate the auto zero/span cycle or sequence, return to the Attendant Zero/Span menu and select the menu Prfrm AUTO_ZS cycle. Once in the menu, verify that the value for CO2 Span Gas matches the molar mixing ratio in ppm of the CO2 span gas. If it needs to be edited, highlight the variable, press Enter, type in the correct value, and press Enter again to save.
Next, highlight Pick AUTO_ZS, press Enter, make sure AUTO_ZS is highlighted, and press Enter. This initiates the automatic zero/span cycle; Table 8-2 (p. 116) shows the sequence and timing
CPEC306/310 Closed-Path Eddy-Covariance Systems 115
through the automatic zero-and-span cycle. The progress of the cycle may be monitored on the CR1000KD screen by watching Site and Sec On Site. Real-time values of CO2, H2O, gas flow, and system diagnostic are also provided in the menu. Upon completion, the value for variable Pick AUTO_ZS will return to FLD_MEA, indicating that the system measurement mode has returned to normal eddy-covariance field sampling, and Site will return to fld smp, indicating all zero/span valves are closed and ambient air is being pulled into the sample cell.
NOTE: For more information on sampling modes, regimes, and sites, refer to Sampling site, regime, and mode (p. 134).
Timing on most sites is determined by the user-set constant TIME_ZRO_SPN. Some sites may also be skipped, depending on CPEC310-related constants set by the user; see Table 7-1 (p. 39).
Table 8-2: Site sequence and timing in the auto zero-and-span cycle
Step in auto
zero/span cycle
Description Site name Timing (sec)
Omit status (sec of measurements that are omitted from statistics or stored
data)
1
Transition from eddy- covariance field measurements to the zero/span sequence
fld smp 1 1
2
Pump is turned off and system measures the offset between sample cell pressure sensor and ambient pressure sensor.
offst P 15
10 (the first 10 sec are omitted so the system may
equilibrate; the last 5 sec of measurements are used and stored)
3
CO2 span gas flows from its tank to the sample cell. Pump is off. System measures CO2 but does not set CO2 readings to the CO2 span gas concentration.
chk CO2 TIME_ZRO_SPN Default: 60
TIME_ZRO_SPN 5 Default: 55
CPEC306/310 Closed-Path Eddy-Covariance Systems 116
Table 8-2: Site sequence and timing in the auto zero-and-span cycle
Step in auto
zero/span cycle
Description Site name Timing (sec)
Omit status (sec of measurements that are omitted from statistics or stored
data)
4
Zero gas flows from the scrub module or a tank to the sample cell. Pump is off. System measures CO2 and H2O but does not set them to zero.
chk zro TIME_ZRO_SPN + 20 Default: 80
TIME_ZRO_SPN 5 Default: 75
5
Zero gas flows from the scrub module or a tank to the sample cell. Pump is off. Analyzer CO2 and H2Omeasurements are zeroed.
set zro 10 10
6
CO2 span gas flows from tank to sample cell. Pump is off. CO2 span is set during the last 10 seconds.
set CO2 TIME_ZRO_SPN + 30 Default: 90
TIME_ZRO_SPN + 30 Default: 90
71/ H2O span gas flows from its source to sample cell. Pump is off. H2O span is not set, just measured.
chk H2O 3*TIME_ZRO_SPN Default: 180
3*TIME_ZRO_SPN 5 Default: 175
CPEC306/310 Closed-Path Eddy-Covariance Systems 117
Table 8-2: Site sequence and timing in the auto zero-and-span cycle
Step in auto
zero/span cycle
Description Site name Timing (sec)
Omit status (sec of measurements that are omitted from statistics or stored
data)
81/ H2O span is set on the analyzer. set H2O 10 10
9
System prepares to resume operation in normal eddy covariance field measurement mode. All valves to zero and span gases are closed. Pump is on, and ambient air is pulled through sample cell.
equilib 30 30
1/Because it is difficult to have an autonomous field H2O span gas source, these steps in the auto zero/span sequence are skipped.
8.1.2 CPEC310 manual H2O span Since the CPEC310 automatic zero/span cycle does not include an H2O span, a manual H2O span may be set up and initiated as follows.
The user must first connect tubing from an H2O span gas source (such as a dew point generator) to the H2O Span port on the CPEC310 system enclosure. Turn on the dew point generator and allow H2O span gas to flow. Even though the valve module is not yet allowing H2O span gas to flow to the analyzer, back pressure is not an issue, as the CPEC310 system enclosure is designed to vent excess H2O span gas flow.
Next, navigate to the Prfrm Field H2O Span menu found under the Attendant Zero/Span menu. Within this menu, verify that the value of H2O Spn T_DP matches the dew point setting on the H2O span gas source/generator. If this value needs to be edited, highlight it, press Enter, type in the new value, and press Enter again to save. Next, highlight Pick SPN_H2O, press Enter, select SPN_H2O, and press Enter. This will initiate an automatic sequence that is a subset of the auto zero/span cycle shown in Table 8-2 (p. 116); specifically, it will progress only through steps 1, 6, 7, and 8 of the steps shown in Table 8-2 (p. 116). Progress of the H2O span may be monitored by viewing the variables Site and Sec on Site. While Site reads chk H2O, monitor the real-time
CPEC306/310 Closed-Path Eddy-Covariance Systems 118
readings of H2O in the sample cell and ensure they have reached equilibrium (as in, they are not changing) before Site switches to set H2O. If equilibrium was not reached, the constant TIME_ ZRO_SPN needs to be increased (see Set constants [p. 36]).
Upon completion of the H2O span, the value of Pick SPN_H2O will return to FLD_MEA, indicating that the system measurement mode has returned to normal eddy-covariance field sampling, and Site will return to fld smp, indicating that all zero/span valves are closed, and ambient air is being pulled into the sample cell. Table 8-2 (p. 116) includes descriptions of variables in the the menus related to zero and span.
NOTE: If the CPEC310 system enclosure is a long distance from the EC155 gas analyzer (for example, a tall tower installation), it may be necessary to increase the value of the constant TIME_ZRO_ SPN (see Set constants [p. 36]) to allow for more equilibration time, especially for H2O. If the tubing is so long that it becomes impractical to wait for equilibration, the dew point generator may be taken up the tower and connected via a short length of tubing to the Zero/Span port on the back of the EC155. If this type of manual setup for doing an H2O span is used, it may be easier to take a laptop PC up the tower and use ECMon software to do the H2O span. See the EC155 CO2/H2O Closed-Path Gas Analyzermanual for details on doing a span using ECMon.
8.2 User-initiated manual zero/span for CPEC306 The CPEC306 does not contain a valve module; therefore, this system requires the user to manually connect and flow a zero or span gas through the gas analyzer. The tubing carrying the zero or span gas should be connected to the port labeled Zero/Span on the back of the EC155 gas analyzer head, and the zero or span gas flow should be set using a flow regulator as described in the EC155 CO2/H2O Closed-Path Gas Analyzermanual. Once plumbing connections are prepared, the following sections may serve as a guide to set the zero, CO2 span, or H2O span.
NOTE: When doing manual zero and/or spans, track the drift of the analyzer. This requires the user to first check the CO2 and/or H2O readings against their span gas concentrations and against the zero gas before setting either the zero or span. Refer to the EC155 CO2/H2O Closed-Path Gas Analyzermanual for more information on tracking the analyzer gain and offset.
CPEC306/310 Closed-Path Eddy-Covariance Systems 119
NOTE: If errors in setting up and performing a zero or span lead to nonsensical measurements or a despondent state of the analyzer, the analyzer CO2 and H2O coefficients may be restored to previous values by navigating to Zero span coeffs under the Initial Configuratn menu. Once in this menu, highlight Reset zro/spn coefs and press Enter. To change a coefficient, highlight the corresponding Rst coef, press Enter, type the desired value, and change Set change to TRUE to save the value. If the previous coefficient value is unknown, enter 1.00, which will restore it to its factory settings. The analyzer is now reset, and a proper zero/span may be attempted again.
8.2.1 CPEC306 manual zero If zeroing the analyzer, use the CR1000KD keypad to navigate to the Attendant Zero/Span menu and then to the Prfrm Field Zero menu. Scroll down and highlight Pump Off, press Enter, highlight TRUE, and press Enter again. The pump is now turned off. Make sure the zero gas tubing is connected to the Zero/Span port on the back of the EC155 gas analyzer head and allow zero gas to flow. If needed, use higher flows (>1 Lmin-1) initially to flush out the sample cell, and then return to a low flow (<0.5 Lmin-1) when preparing to check and/or set the zero.
As zero gas is flowing, watch the CO2 and H2O readings until they indicate that the zero gas has flushed the sample cell and equilibrium has been reached. Then highlight Do Zero found at the bottom of the menu, press Enter, highlight TRUE, and press Enter again. The zero will take a few seconds to set, during which time the gas analyzer measurements may not be updated. Upon completion of setting the zero, the value of Do Zero will return to FALSE. Throughout the process of performing the zero, real-time measurements of CO2, H2O, and system diagnostic are displayed in the Prfrm Field Zero menu for convenience. If no additional zeros or spans are to be performed, Pump Off should be set back to FALSE to resume operation of the pump and resume normal eddy-covariance field measurements.
8.2.2 CPEC306 manual CO2 span If performing a CO2 span of the analyzer, use the CR1000KD keypad to navigate to the Attendant Zero/Span menu and then to the Prfrm Field CO2 Span menu. Scroll down and highlight Pump Off, press Enter, highlight TRUE, and press Enter again. The pump is now turned off. Make sure the CO2 span gas tubing is connected to the Zero/Span port on the back of the EC155 gas analyzer head and allow CO2 span gas to start flowing. If needed, use higher flows (>1 Lmin-1) initially to flush out the sample cell, and then return to a low flow (<0.5 Lmin-1) before checking and/or setting the CO2 span. Within the Prfrm Field CO2 Span menu, verify that the variable CO2 Spn Gas matches the concentration reported on the tank of the CO2 span gas. If this value needs editing, highlight it, press Enter, type in the new value, and press Enter again to save the value.
CPEC306/310 Closed-Path Eddy-Covariance Systems 120
The Prfrm Field CO2 Span menu also includes readings of CO2molar mixing ratio. Watch the readings until they indicate that the span gas has flushed out the sample cell and equilibrium has been reached.
Once equilibrium is attained, highlight Do CO2 Span found at the bottom of the menu, press Enter, highlight TRUE, and press Enter again. Setting the CO2 span will take a few seconds, during which time measurements from the gas analyzer may not be updated. Upon completion of the CO2 span, the value of Do CO2 Span will return to FALSE. Throughout the CO2 span, real-time measurements of CO2 and system diagnostic are included in the Prfrm Field CO2 Span menu for convenience. If no additional zeros or spans are to be performed, Pump Off should be set back to FALSE to resume operation of the pump and resume normal eddy-covariance field measurements.
8.2.3 CPEC306 manual H2O span If performing an H2O span of the analyzer, use the CR1000KD keypad to navigate to the Attendant Zero/Span menu and then to the Prfrm Field H2O Span menu. Scroll down and highlight Pump Off, press Enter, highlight TRUE, and press Enter again. The pump is now turned off. Make sure the H2O span gas tubing is connected to the Zero/Span port on the back of the EC155 gas analyzer head and allow H2O span gas to start flowing. If needed, use higher flows (>1 Lmin-1) initially to flush out the sample cell, and then return to a low flow (<0.4 Lmin-1) before checking or setting the H2O span. Within the Prfrm Field H2O Span menu, verify that the variable H2O Spn T_DP is set to the dew point temperature setting on the dew point generator or other H2O span gas source. If this value needs editing, highlight it, press Enter, type in the new value, and press Enter again to save.
The Prfrm Field H2O Span menu includes readings of H2Omolar mixing ratio in the sample cell. Watch the readings until they indicate that the span gas has flushed out the sample cell and equilibrium has been reached. Once equilibrium is attained, highlight Do H2O Span found at the bottom of the menu, press Enter, highlight TRUE, and press Enter again. Setting the H2O span will take a few seconds, during which time the gas analyzer measurements may not be updated. Upon completion of the H2O span, Do H2O Span will return to FALSE. Throughout the H2O span, real-time measurements of H2O and system diagnostic are included in the Prfrm Field H2O Span menu for convenience. If the system includes a temp/RH probe, the ambient dew point temperature is also reported for reference. If no additional zeros or spans are to be performed, Pump Off should be set back to FALSE to resume operation of the pump and resume normal eddy-covariance field measurements.
CPEC306/310 Closed-Path Eddy-Covariance Systems 121
9. Maintenance and troubleshooting Most of the basic diagnostic and troubleshooting issues for the CPEC-series systems are indicated in the Diagnostic data output table (Table 7-9 [p. 67]). This section provides additional detail on some issues that may arise with hardware components.
9.1 Enclosure desiccant Check the humidity indicator card in the mesh pocket in the CPEC-series system enclosure door and the EC100 enclosure door. The humidity indicator card has three colored circles that indicate the percentage of humidity (see Figure 4-19 [p. 17]). Desiccant packets inside the enclosure should be replaced with fresh packets when the upper dot on the indicator begins to turn pink. The indicator card does not need to be replaced unless the colored circles overrun. Both the desiccant packs and humidity cards can be purchased as replacements. See Replacement parts (p. 15) for more detail.
CAUTION: Campbell Scientific strongly suggests replacing desiccant instead of reactivating old desiccant. Improper reactivation can cause the desiccant packets to explode.
If the desiccant packs in a CPEC-series system enclosure require frequent replacement, check that the feedthrough cap is properly installed. In very humid conditions, it may be helpful to seal the cable feedthrough with plumbers putty as described in Apply power (p. 33).
9.2 EC155 windows The EC155 gas analyzer reports a signal strength for both CO2 and H2O that decreases as the optics become contaminated. The factory calibration procedure allows some tolerance to window contamination. In general, the tolerance is higher for contaminants that are uniformly distributed on the windows and have flat spectral characteristics than for contaminants, such as water droplets, that can greatly disperse or refract the optical beam. The signal strength should be monitored as part of any quality assurance/quality check of incoming data. If the signal strength has dropped, CO2 and H2O values should be checked for validity, and windows should be cleaned during the next site visit. Clean the windows as instructed in the EC155 CO2/H2O Closed-Path Gas Analyzermanual before the CO2 and H2O signals reach 0.80.
CPEC306/310 Closed-Path Eddy-Covariance Systems 122
NOTE: In an EC155 that has vortex intake, a decrease in signal strength likely means that the vortex filter is plugged and should be replaced.
9.3 EC155 molecular sieve bottles If zero-and-span readings have drifted excessively, the molecular sieve bottles within the EC155 analyzer head should be replaced as detailed in the EC155 CO2/H2O Closed-Path Gas Analyzer manual.
9.4 Pump module filter In very humid conditions, water may condense and collect inside the housing of the filter in the pump module enclosure. This is normal and will have no effect on the measurements. In most cases, the water will evaporate as ambient conditions change.
9.5 Testing wind offset Usually, the CSAT3A sonic anemometer calibration remains valid unless a transducer fails or damage to the instrument leads to a change in geometry. The sonic anemometer requires calibration under two conditions:
l Developing a wind offset greater than the specification l Setting diagnostic flags under dry conditions with little to no wind and with no obstruction in the ultrasonic paths
The wind offset is tested by creating a zero-wind environment. This is best done in a laboratory setting with HVAC vents closed or covered to reduce air currents, and by encircling the mounted sensor with a large plastic bag (for example, an unused trash bag). Caution should be used to not block the sonic paths. Once the CSAT3A is connected to an EC100 and powered on, wind offsets may be viewed by connecting the EC100 to a PC and using ECMon to graph ux, uy, and uz wind components. In this zero-wind environment, ux and uy should be less than 8 cms-1 (0.08 ms-1), and uz should be less than 4 cms-1 (0.04 ms-1). If recalibration is deemed necessary, contact Campbell Scientific.
CPEC306/310 Closed-Path Eddy-Covariance Systems 123
10. Repair All CPEC-series systems are designed to give years of trouble-free service with reasonable care. However, if factory repair is needed, contact Campbell Scientific to obtain an RMA number. An RMA number and product safety documents are required prior to the acceptance of any repair shipments at Campbell Scientific. See details in the Assistance section at the end of this document.
Contact Campbell Scientific to determine which parts or assemblies should be sent for repair. See www.campbellsci.com/cpec300 for the appropriate contact. If the system enclosure is to be returned, plug the inlets and cap the ends of all tubes to keep debris out. Swagelok caps and plugs have been provided for this purpose.
CPEC306/310 Closed-Path Eddy-Covariance Systems 124
Appendix A. EasyFlux DL CR6CP process flow A.1 Sequence of program functions A.1.1 Every SCAN_INTERVAL (default 100 ms)
Collect raw data from GPS sensor, battery voltage, CDM panel temp, FW, and rain gage.
Store FWmeasurements in a table to be used later to align with sonic data.
Check for conditions that require EC100 reconfiguration.
Store sonic and gas data from the previous scan in temporary tables that will be used in later
steps to align measurements and calculate covariances.
If the time for zero/span is approaching, turn on valve module heater (and scrub module heater,
if applicable).
Calculate mean variables (for example, call site_block_mean table).
Check to see if the mode of operation has changed. If yes, perform functions associated with
that mode (such as zero and span); when finished, return to eddy-covariance field measurements.
Record the prior scan time series data into final storage.
CPEC306/310 Closed-Path Eddy-Covariance Systems 125
Parse out sonic diagnostic data, and filter bad sonic data from being included in statistical data.
Send sonic data to covariance tables to be included for 5 min and averaging interval
covariances.
Parse out gas diagnostic data, and filter bad gas data from being included in statistical data.
Calculate climate and gas variables (for example, e, rho_d, rho_a, Td, CO2_mixratio,
H2O_mixratio, RH).
Store gas data into multiple datasets or temporary tables that each have a different lag relative to sonic data (to be used later in cross correlation; lags from MAX_LAG to +MAX_LAG are used;
MAX_LAG default is 2); for each dataset with a particular lag, recalculate cell and ambient climate variables.
If using FW, store raw data in multiple datasets, each dataset with a different lag applied to FW
data relative to sonic data (to be used later in cross correlation; lags from MAX_LAG to +MAX_LAG are used; MAX_LAG default is 2).
Control pump speed to achieve pressure set point.
Measure rain gage.
Record time series measurement diagnostics in the Diagnostic output table.
Ingest new raw sonic and gas measurements from the EC100.
CPEC306/310 Closed-Path Eddy-Covariance Systems 126
A.1.2 Every SLOWSEQUENCE_SCAN_INTERVAL (default 5 sec)
Measure CR6 panel temp.
Measure biomet and energy balance (slow response) sensors.
Calculate albedo.
If using self-calibrating heat flux plates and a new calibration interval has started, perform the
auto calibration.
If station variables have changed, save new values to memory.
System power control (if needed, power down gas analyzer and pump).
Temp control for valve and scrub modules.
If a zero/span has completed, save new gain and offset values and store zero/span outputs to
ZeroSpan_Check_Notes and EC100_config _Notes tables.
A.1.3 Every 5 min Do coordinate rotations and find the 5-minute covariances for u with w, v with w, Ts with w, CO2 with w, and H2O with w (used later for steady state test for quality grading; see EasyFlux DL
CR6OP or CR1KXOPmanual, Appendix F, Data quality grading for more details).
CPEC306/310 Closed-Path Eddy-Covariance Systems 127
A.1.4 Every AVERAGING_INTERVAL (default 30 min) Filter out data with diagnostic flags or signal strengths or
measurements outside of acceptable ranges.
Do coordinate rotations (use double coordinate rotation method unless planar fit angles have been entered by user) to find rotated orthogonal wind components, u, v, and w. Calculate sonic-related
covariances (such as wTs, wu, vw). (See EasyFlux DL CR6OP or CR1KXOP manual: Appendix B, Coordinate rotations: Double rotation method
and Appendix C, Coordinate rotations: Planar fit method.)
Use rotated wind components to find turbulent kinetic energy, friction velocity, and preliminary values of Monin-Obukhov length and stability.
Calculate frequency correction factors for wTs, wu, and vw to account
for block averaging and line averaging. If conditions are stable, iteratively calculate Monin-Obukhov length, cospectral equations, and correction factors until factors change by <0.0001 or until 10 iterations
have completed. (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix D, Frequency corrections.)
Calculate value for steady state test using the 30-minute momentum covariances and the 5-minute momentum covariances. (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix F, Data quality grading.)
Calculate the overall quality grade for momentum flux. (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix F, Data quality grading.)
CPEC306/310 Closed-Path Eddy-Covariance Systems 128
Calculate and use a new roughness length if: (1) the user did not enter a fixed value, (2) there is neutral stability, and (3) wind speed is >3 m/s and momentum flux quality grading is adequate (QC 6.0). (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix G, Footprint.)
Calculate footprint characteristics using the Kljun et al. (2004) model if conditions are appropriate, otherwise use the Kormann and Meixner (2001) model. (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix
G, Footprint.)
Calculate the covariance of CO2 and wind components for each lagged
dataset and do coordinate rotation on covariances.
Find the effective lateral separation distance between gas analyzer and sonic (to use in frequency correction) and the effective separation scan lag (used to constrain which lagged datasets are physically possible). (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix D, Frequency
corrections.)
Find the dataset with the physically possible lag that maximizes the covariance of CO2 and vertical wind. Use this dataset for the Flux_ AmeriFluxFormat and Flux_CSFormat output tables. If any results are invalid, continue with lag of zero. (See EasyFlux DL CR6OP or CR1KXOP
manual, Appendix D, Frequency corrections.)
Calculate cospectra functions and the frequency correction factor for CO2-related covariances, taking into account attenuation from block averaging, line averaging, spatial separation, and tube attenuation. (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix D, Frequency corrections; Ibrom et al. 2007; Burgon et al. 2015; program code.)
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Calculate covariances of H2O and wind components for each lagged dataset and do coordinate rotation on covariances.
Find the dataset with the physically possible lag that maximizes the
covariance of H2O and vertical wind. Use this dataset for the Flux_AmeriFluxFormat and Flux_CSFormat output tables. If any results are invalid, continue with lag of zero. (See EasyFlux DL CR6OP or
CR1KXOPmanual, Appendix D, Frequency corrections.)
Calculate the frequency correction factor for covariances of H2O and rotated wind components, taking into account attenuation from block averaging, line averaging, spatial separation, and tube attenuation. (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix D, Frequency corrections; Ibrom et al. 2007; Burgon et al. 2015; program code.)
Calculate final momentum flux from rotated and frequency corrected
covariances of u with w and v with w.
Apply SND correction to the rotated and frequency corrected
covariance of w and Ts.
Calculate specific heat of ambient (moist) air and calculate final sensible
heat flux.
Calculate scaling temperature (used for data quality grading). (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix F, Data quality
grading.)
Calculate Bowen Ratio.
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Calculate the overall quality grades for fluxes of sensible heat, latent
heat, and CO2. (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix F, Data quality grading.)
If energy balance sensors are
used
Calculate soil surface energy flux for the averaging interval. (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix H, Surface energy
flux.)
Get calculated measurements of H, LE, and Rnet for the averaging interval.
Calculate energy closure.
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If FW05, FW1, or FW3 is used
Calculate the covariance of FW temperature and wind components for each lagged dataset, then perform coordinate rotations on
covariances.
Find the effective lateral separation distance between FW and sonic (to use in frequency correction) and the effective separation scan lag (used
to constrain which lagged datasets are physically possible). (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix D, Frequency
corrections.)
Find the dataset with the lag that maximizes the covariance of FW temperature and vertical wind. Use this dataset for the Flux_
AmeriFluxFormat and Flux_CSFormat output tables. If any results are invalid, continue with lag of zero.
Calculate the time constant for the FW (to be used in frequency
corrections). (See EasyFlux DL CR6OP or CR1KXOPmanual, Appendix D, Frequency corrections.)
Calculate frequency correction factors for covariances of FW
temperature and rotated wind components, taking into account attenuation from block averaging, line averaging, spatial separation, and the FW time constant. (See EasyFlux DL CR6OP or CR1KXOP
manual, Appendix D, Frequency Corrections.)
Calculate final fine-wire sensible heat flux.
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Write records to the Flux_AmeriFluxFormat, Flux_CSFormat, and Flux_Notes output tables.
Calculate the number of days remaining on the data storage card of
the data logger.
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Appendix B. Sampling site, regime, and mode Sampling sites, regimes, and modes are applicable to CPEC310 and help distinguish certain states of the system. A sampling site refers to a particular valve selection or air sampling source. Table B-1 (p. 135) provides a list of the defined sampling sites.
A sampling regime consists of a site designation, a state of the pump (on or off), and an omit status, which is whether or not the current measurements are being included in calculations and statistics. For example, the steps in the auto zero/span sequence in Table 8-2 (p. 116) each describe a sampling regime. The sampling regime at a given moment is described by the variable sampling_regime, which is included in the Time_Series output table, where bits 0 through 3 correspond to the site number, and bit 4 is set when measurements are being omitted from calculations. For example, if the system has just finished an auto zero-and-span cycle and has returned to normal eddy-covariance measurements (site 1), it will omit measurements from the covariance and other calculations for 25 seconds in order for the sample cell to be thoroughly flushed and the pressure equilibrated; during this 25-second time period, sampling_regime will have a value of 17, where bit 4 is set high (decimal value of 16) to indicate omitted measurements, and bit 0 is set to 1 (decimal value of 1), corresponding to site 1. After the 25- second period has passed, sampling_regime will show a value of 1, indicating the measurements are no longer omitted and the current site is site 1.
A sampling mode, or simply mode, is a timed or controlled sequence of one or more sampling regimes. Table B-2 (p. 135) lists the various modes. For example, in the case of AUTO_ZS mode, a sequence of several sampling regimes is completed to perform a zero and span of the gas analyzer.
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Table B-1: Site numbers, text descriptors, and descriptions
Site number
Text descriptor of site (used on
CR1000KD display) Description
1 fld smp Normal field sampling; pump is on and pulling ambient air into the sample cell
2 offst P Pump is off; this setting is used to measure the offset between the sample cell pressure sensor and the EC100 barometer
3 chk CO2 Check CO2 span
4 chk zro Check zero
5 set zro Set zero
6 set CO2 Set CO2 span
7 chk H2O Check H2O span
8 set H2O Set H2O span
9 equilib Idle or equilibration with ambient mode; pump is off
10 irg_off Sleep or power-saver mode; EC155 and pump turned off, while CSAT3A remains on
Table B-2: Mode names and descriptions
Mode name Description
FLD_MEA Eddy-covariance field measurement mode. Pump is on, and ambient air is sampled (site 1). Measurements from the first 25 sec after switching to this mode are omitted from calculations.
PUMP_OFF Pump off mode. Pump is turned off, sample cell pressure equilibrates to ambient pressure, and a measurement of the pressure offset is made.
ZRO_ALL
User-initiated automatic zero all mode (applicable to CPEC310 systems). After a zero gas source is connected to the CPEC310 system enclosure and gas is flowing, this mode may be selected so the system will go through a sequence of sampling regimes that will zero the gas analyzer.
CPEC306/310 Closed-Path Eddy-Covariance Systems 135
Table B-2: Mode names and descriptions
Mode name Description
SPN_CO2
User-initiated automatic CO2 span mode (applicable to CPEC310 systems). If a CO2 span gas source is connected to the CPEC310 system enclosure and gas is flowing, this mode may be selected so the system will go through a sequence of sampling regimes that will span the CO2 of the gas analyzer.
SPN_H2O
User-initiated automatic H2O span mode (applicable to CPEC310 systems). After an H2O span gas source is connected to the CPEC310 system enclosure and gas is flowing, this mode may be selected so the system will go through a sequence of sampling regimes that will span the H2O of the gas analyzer.
IRG_SLP IRGA sleep mode. Powers down the gas analyzer and pump and leaves the CSAT3A powered on and making measurements.
AUTO_ZS
Automatic zero and span mode. Will automatically check and/or set the zero and CO2 span of the gas analyzer. Whether or not the zero and span are set depends on the values to which the user set the zero/span constants. See Set constants (p. 36).
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Appendix C. Wiring the CR6 and optional energy balance sensors C.1 Overview The user should install sensors and system components according to the respective product manuals. For standard program usability, when wiring the sensors to the data logger or to a VOLT 116, the user should follow the default wiring schemes, along with the type and quantity of instruments supported by EasyFlux DL CR6CP. Table C-1 (p. 138) through Table C-13 (p. 149) present the wiring schemes.
The minimum required equipment to operate EasyFlux DL CR6CP is one of the CPEC-series systems with its core components, as described in the introduction. The additional sensors described in Sections C.1.3 through C.1.12 are optional. The VOLT 116 is required for some optional sensors, since the CR6 itself does not contain enough channels for a full energy balance sensor suite; the VOLT 116 effectively increases the CR6 analog channels. If one or more of the optional sensors is not used, the data logger or VOLT 116 module terminals assigned to the wires of that sensor should be left unwired.
NOTE: If the standard data logger program is modified, the wiring presented in Table C-1 (p. 138) may no longer apply. In these cases, refer directly to the program code to determine proper wiring, or contact Campbell Scientific for assistance.
C.1.1 IRGA and sonic anemometer A closed-path EC155 gas analyzer and CSAT3A sonic anemometer must be connected to the EC100 electronics, and the EC100 must be wired to a CR6 data logger via a wiring terminal for EasyFlux DL CR6CP to be functional. Table C-1 (p. 138) shows the default wiring for these sensors.
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Table C-1: Default wiring for EC155 and CSAT3A(H) sonic anemometer
Sensor Quantity Wire description Wire color CPEC system enclosure wiring terminal
EC155 and CSAT3A (from EC100) 1
SDM data Green C1
SDM clock White C2
SDM enable Red/brown C3
Signal ground Black G
Shield Clear G
C.1.2 VOLT 116 module Due to the limitations on channel count of the CR6, a VOLT 116 module is required when using a fine-wire thermocouple, a temp/RH probe, radiation sensors, soil temperature probes, and/or soil heat flux plates. A CPEC-series system already has a VOLT 116 installed, connected to the CR6, and configured, but it can be reconfigured if needed, as follows:
1. Connect the module to a 10-32 VDC power source.
2. Launch the Campbell Scientific Device Configuration Utility software (v2.12 or newer) and select VOLT 100 Series among the list of GRANITE devices. If this is the first time connecting, follow the instructions on the main screen to download the USB driver to the computer.
3. Select the appropriate COM port and click Connect.
4. Once connected, a list of settings is shown. Navigate to the bottom setting, CPI Address. Change this value to 1. Click Apply and exit the software.
5. Use a CAT5e or CAT6 Ethernet cable (included with the VOLT 116) to connect the CPI port on the module to the CR6 or CR1000X CPI port.
C.1.3 GPS receiver A GPS receiver such as the GPS16X-HVS is optional but will keep the data logger clock synchronized to GPS time. If the CR6 clock differs by one millisecond or more, EasyFlux DL CR6CP will resynchronize the data logger clock to match the GPS. The GPS receiver also calculates solar position. Table C-2 (p. 139) shows the default wiring for the GPS16X-HVS.
CPEC306/310 Closed-Path Eddy-Covariance Systems 138
Table C-2: Default wiring for GPS receiver
Sensor Quantity Wire description Wire color CR6 terminal
GPS16X-HVS 0 or 1
PPS Grey U1
TXD White U2
Shield Clear AG
12V Red 12V
Power ground Black G
Power switch Yellow G
Rx data Blue G
C.1.4 Fine-wire thermocouple Several models of fine-wire thermocouple sensors are available that can be integrated with the IRGA and sonic anemometer for direct measurements of sensible heat flux. EasyFlux DL CR6CP can support from zero to one fine-wire thermocouple with the IRGA and sonic anemometer. Table C-3 (p. 139) shows the available types of and default wiring for adding a fine-wire thermocouple.
Table C-3: Default wiring for fine-wire thermocouple
Sensor Quantity Wire description Wire color CPEC-series system terminal
FW05, FW1, or FW3 0 or 1
Signal Purple CDM Diff 6H
Signal reference Red CDM Diff 6L
Shield Clear CDM AG
C.1.5 Temperature and relative humidity probe EasyFlux DL CR6CP can support from zero to one temperature and relative humidity probe. The default wiring for the HMP155A, EE181, and HygroVUE10 is shown in Table C-4 (p. 140).
NOTE: Table C-4 (p. 140) shows wiring for the HMP155A, EE181, and HygroVUE10 temperature and humidity probes. Alternatively, an older model probe such as the HMP45C or HC2S3 may be used, but wiring for these models is not shown here. Instead, their wiring may be found in the
CPEC306/310 Closed-Path Eddy-Covariance Systems 139
respective product manuals found at www.campbellsci.com . In any case, the user should carefully note the colors of the wires and jumper wire configuration of the probe being used. Table C-4 (p. 140) shows wire colors for HMP155A in regular text; colors for EE181 are noted by italic text.
Table C-4: Default wiring for temperature and relative humidity probe
Probe Quantity Wire description Wire color VOLT 116 terminal
HMP155A/ EE181
0 or 1 (cannot be used
with HygroVUE10)
Temp signal Yellow/yellow Diff 16H
Temp signal reference White/black AG
RH signal Blue/blue Diff 16L
RH signal reference White/black AG
Shield Clear/clear AG
Power Red/red +12 V
Power ground Black/black G
HygroVUE10
0 or 1 (cannot be used with HMP155A or EE181)
Temp/RH signals White U11
Temp/RH reference Clear AG
Power Brown 12 V
Power ground Black G
C.1.6 Radiation measurements, Option 1 Two options are available for making radiation measurements with EasyFlux DL CR6CP. The program can support any combination of the four sensors described in Table C-5 (p. 141). Alternatively, it can support one of the three types of 4-component radiometers described in Table C-6 (p. 142). Table C-5 (p. 141) gives the default wiring for Option 1. Table C-6 (p. 142) shows the details of the default wiring for Option 2.
CPEC306/310 Closed-Path Eddy-Covariance Systems 140
Table C-5: Default wiring for radiation measurements, Option 1
Sensor Quantity Wire description Wire color VOLT 116 terminal (unless otherwise indicated)
CS301 pyranometer 0 or 1
Signal White Diff 2H
Signal reference Black Diff 2L
Shield Clear AG
CS320 digital thermopile pyranometer
0 or 1
SDI-12 signal White CR6 U11
Signal reference Blue CR6 AG
Shield Clear CR6 AG
Power Red CR6 12V
Power ground Black CR6 G
CS310 quantum sensor
0 or 1
Signal White Diff 3H
Signal reference Black Diff 3L
Shield Clear AG
SI-111 infrared radiometer 0 or 1
Target temp signal Red Diff 4H
Target temp reference Black Diff 4L
Shield Clear AG
Sensor temp signal Green Diff 5H
Sensor temp reference Blue AG
Voltage excitation White X1
C.1.7 Radiation measurements, Option 2 Three models of 4-component net radiometers are compatible with the EasyFlux DL CR6CP program: SN500SS, NR01, and CNR4. However, due to limitations in channel numbers and computation procedures, only one model can be used at a time. The default wiring for each of the 4-component net radiometers is shown in Table C-6 (p. 142). Table C-9 (p. 146) and Table C- 10 (p. 146) give information on adding an optional CNF4 ventilation and heater unit to the CNR4 4-component net radiometer.
A CNF4 ventilation and heater unit may be used with the CNR4 4-component net radiometer for more accurate radiation measurements. The CNF4 requires a solid-state relay to control the ventilator and heater. An A21REL-12 4-channel relay driver must be ordered (sold separately) and
CPEC306/310 Closed-Path Eddy-Covariance Systems 141
installed in the system enclosure just below the VOLT 116 module. Table C-7 (p. 144) lists the wiring connections needed to power and control the A21REL-12. Table C-8 (p. 145) lists the wiring for the CNF4.
A CABLE3CBL-1 or similar 3-conductor 22 AWG cable is recommended for connections from the A21REL-12 to the VOLT 116, and a CABLEPCBL-1 or similar 2-conductor 16 AWG power cable is recommended for power connections from the A21REL-12 to the DIN rail terminal block.
For the CPEC310, no additional relay driver is required, since the system already includes an SDM-CD16S; however, some wiring from the valve module must be modified to accommodate the CNF4 (see Table C-6 [p. 142], which lists the wiring for the CNF4 for either the CPEC306 or the CPEC310).
Table C-6: Default wiring for radiation measurements, Option 2
Sensor Quantity Wire description Wire color
VOLT 116 terminal (unless otherwise
indicated)
SN500SS 4-component net radiometer
0 or 1
SDI-12 signal White CR6 U11
Shield Clear CR6 AG
Power Red CR6 12V
Power ground Black CR6 G
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Table C-6: Default wiring for radiation measurements, Option 2
Sensor Quantity Wire description Wire color
VOLT 116 terminal (unless otherwise
indicated)
NR01 4-component net radiometer
0 or 1
Pyranometer up signal Red (cbl 1) Diff 1H
Pyranometer up reference Blue (cbl 1) Diff 1L
Pyranometer down signal White (cbl 1) Diff 2H
Pyranometer down reference Green (cbl 1) Diff 2L
Pyrgeometer up signal Brown/grey or orange (cbl
1) Diff 3H
Pyrgeometer up reference Yellow (cbl 1) Diff 3L
Pyrgeometer down signal
Purple or pink/brown
(cbl 1) Diff 4H
Pyrgeometer down reference
Grey/green (cbl 1) Diff 4L
PT100 signal White/yellow (cbl 2) Diff 5H
PT100 reference Green (cbl 2) Diff 5L
Current excite Red (cbl 2) X2
Current return Blue (cbl 2) AG
Shields Clear AG
Heater power Brown CDM SW121/
Heater ground Yellow G
Ground Purple/pink G
Shield Grey AG
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Table C-6: Default wiring for radiation measurements, Option 2
Sensor Quantity Wire description Wire color
VOLT 116 terminal (unless otherwise
indicated)
CNR4 4-component net radiometer
0 or 1
Pyranometer up signal Red Diff 1H
Pyranometer up reference Blue Diff 1L
Pyranometer down signal White Diff 2H
Pyranometer down reference Black Diff 2L
Pyrgeometer up signal Grey Diff 3H
Pyrgeometer up reference Yellow Diff 3L
Pyrgeometer down signal Brown Diff 4H
Pyrgeometer down reference Green Diff 4L
Thermistor signal White Diff 5H
Thermistor V excite Red X2
Thermistor reference Black AG
Shields Clear AG 1/Use CR6 SW12-1 and G if self-calibrated soil heat flux plate is used.
Table C-7: A21REL-12 wiring (used with CNF4 in a CPEC306 system)
A21REL-12 terminal Connecting terminal Cable Cable color
+12V CPEC306 enclosure DIN rail terminal block: 12V CABLEPCBL-1 Red
Ground CPEC306 enclosure DIN rail terminal block: GND CABLEPCBL-1 Black
CTRL 1 VOLT 116 SW5V #1 CABLE3CBL-1 Red
CPEC306/310 Closed-Path Eddy-Covariance Systems 144
Table C-7: A21REL-12 wiring (used with CNF4 in a CPEC306 system)
A21REL-12 terminal Connecting terminal Cable Cable color
CTRL 2 VOLT 116 SW5V #2 CABLE3CBL-1 Black
CTRL 3 VOLT 116 SW5V #3 CABLE3CBL-1 White
Table C-8: Default wiring for CNF4
Sensor Quantity Wire description Wire color Wiring Wiring
CNF4 0 or 1 (only if CNR4 is used)
Tachometer output Green CR6 U7 CR6 U71/
Tachometer reference Grey CR6 AG CR6 AG 1/
Ventilator power Yellow A21REL-12 REL 1 NO
SDM-CD16S OUT 14
Ventilator ground Brown A21REL-12 REL G
SDM-CD16S OUT G
Heater #1 power White A21REL-12 REL 2 NO
SDM-CD16S OUT 15
Heater #1 ground Red A21REL-12 REL G
SDM-CD16S OUT G
Heater #2 power Black A21REL-12 REL 3 NO
SDM-CD16S OUT 16
Heater #2 ground Blue A21REL-12 REL G
SDM-CD16S OUT G
1/In a CPEC310, wiring the CNF4 requires moving the valve module thermistor signal wire (green) from CR6 U7 to VOLT 116 Diff 5L and the valve module thermistor reference (yellow) from CR6 AG to VOLT 116 AG.
C.1.8 Precipitation gage EasyFlux DL CR6CP can support a single tipping rain gage such as the TE525MM, or a precipitation gage can be omitted. The default wiring for a precipitation gage is shown in Table C-9 (p. 146).
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Table C-9: Default wiring for precipitation gage
Sensor Quantity Wire description Wire color CR6 terminal
TE525MM tipping-bucket rain gage
0 or 1
Pulse output Black U10
Signal ground White AG
Shield Clear AG
C.1.9 Soil temperature The TCAV is an averaging soil thermocouple probe used for measuring soil temperature. EasyFlux DL CR6CP can support up to three TCAV probes. The order of wiring, however, is important. If only one TCAV probe is used, it must be wired as described for TCAV #1 in Table C- 10 (p. 146).
CAUTION: If only one TCAV is being used and it is wired to terminals 8H/8L or 15H/15L (leaving terminals 7H and 7L empty), the data logger will not record any TCAV measurements.
Table C-10: Default wiring for soil thermocouple
Sensor Quantity Wire description Wire color VOLT 116 terminal
TCAV #1
0 to 3
Signal Purple Diff 7H
Signal reference Red Diff 7L
Shield Clear AG
TCAV #2
Signal Purple Diff 8H
Signal reference Red Diff 8L
Shield Clear AG
TCAV #3
Signal Purple Diff 15H
Signal reference Red Diff 15L
Shield Clear AG
NOTE: The CS650 or CS655 sensors also measure soil temperature. If the CS650 or CS655 sensors are used but no TCAV probes are used, EasyFlux DL CR6CP will use soil temperature from the CS650 or CS655 to compute ground-surface heat flux. If available, soil temperature data from
CPEC306/310 Closed-Path Eddy-Covariance Systems 146
the TCAV probe is preferred because it provides a better spatial average. See wiring details for these sensors in Table C-11 (p. 147).
C.1.10 Soil water content reflectometers EasyFlux DL CR6CP supports zero or one of two models of soil water content reflectometers: CS650 or CS655, and up to three of the one selected model are supported. The default wiring for each is shown in Table C-11 (p. 147).
CAUTION: If only one soil water content reflectometer is being used, the user should wire it according to the first sensor as described in Table C-11 (p. 147). If only one sensor is being used but is wired according to the second or third sensor, EasyFlux DL CR6CP will record no soil water content measurements.
Table C-11: Default wiring for soil water content reflectometers
Sensor Quantity Wire description Wire color CR6 terminal
CS650/ CS655 #1
0 to 3
SDI-12 data Green U11
SDI-12 power Red +12 V
SDI-12 reference Black G
Shield Clear G
Not used Orange AG
CS650/ CS655 #2
SDI-12 data Green U11
SDI-12 power Red +12 V
SDI-12 reference Black G
Shield Clear AG
Not used Orange G
CS650/ CS655 #3
SDI-12 data Green U11
SDI-12 power Red +12 V
SDI-12 reference Black G
Shield Clear AG
Not used Orange G
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C.1.11 Soil heat flux plates EasyFlux DL CR6CP can support from zero to three soil heat flux plates. They can be the HFP01 plates (non-self-calibrating) or the HFP01SC (self-calibrating) plates. The default wiring for the HFP01 standard (non-self-calibrating) soil heat flux plates is shown in Table C-12 (p. 148).
Table C-12: Default wiring for non-self-calibrating soil heat flux plates
Sensor Quantity Wire description Wire color VOLT 116 terminal
HFP01 #1
0 to 3
Signal White Diff 9H
Signal reference Green Diff 9L
Shield Clear AG
HFP01 #2
Signal White Diff 10H
Signal reference Green Diff 10L
Shield Clear AG
HFP01 #3
Signal White Diff 11H
Signal reference Green Diff 11L
Shield Clear AG
C.1.12 Self-calibrating soil heat flux plates If using HFP01SC self-calibrating soil heat flux plates, EasyFlux DL CR6CP can support from zero to three of them. The default wiring for the self calibrating soil heat flux plates is shown in Table C-13 (p. 149).
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Table C-13: Default wiring for self-calibrating soil heat flux plates
Sensor Quantity Wire description Wire color VOLT 116 terminal
HFP01SC #1
Signal White Diff 9H
Signal reference Green Diff 9L
Shield Clear AG
Heater signal Yellow Diff 12H
Heater reference Purple Diff 12L
Shield Clear AG
Heater power Red SW12-11/
Power reference Black G
HFP01SC #2 0 to 3
Signal White Diff 10H
Signal reference Green Diff 10L
Shield Clear AG
Heater signal Yellow Diff 13H
Heater reference Purple Diff 13L
Shield Clear AG
Heater power Red SW12-11/
Power reference Black G
HFP01SC #3
Signal White Diff 11H
Signal reference Green Diff 11L
Shield Clear AG
Heater signal Yellow Diff 14H
Heater reference Purple Diff 14L
Shield Clear AG
Heater power Red SW12-21/
Power reference Black G 1/The SW12 terminals on the VOLT 116 are limited to 200 mA output, so no more than two HFP01SC sensors may be connected to each terminal. The user should connect heater power wires from HFP01SC #1 and #2 to SW12-1 and connect heater wires from HFP01SC #3 to SW12-2.
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Appendix D. System diagnostic word Possible system flags are listed in Table D-1 (p. 150).
Table D-1: Description of bits for system diagnostic
Bit Decimal Name Function
0 1 sonc_er Sonic error. If any error condition or diagnostic flag is set on the sonic anemometer, this bit is set.
1 2 irga_er IRGA error. If any error condition or diagnostic flag is set on the gas analyzer, this bit is set.
2 4 pump_tmpr_er Pump temperature error. If pump temperature is <0 C or >55 C, this bit is set.
3 8 pump_flow_er Pump flow error. If pump flow is more than 0.5 Lmin-1 from the pump flow set point (default set point is 8 Lmin-1), this bit is set.
4 16 valv_tmpr_er Valve temperature error. If valve module temperature is <2 C or >50 C, this bit is set.
5 32 valv_flow_er Valve flow error. If zero or span gas flow through the valve module is more than 0.5 Lmin-1 from the valve flow set point (default set point is 1 Lmin-1), this bit is set.
6 64 scrb_tmpr_er Scrub temperature error. If scrub temperature is <5 C or >50 C, this bit is set.
CPEC306/310 Closed-Path Eddy-Covariance Systems 150
Appendix E. Quality grading Table E-1 (p. 151) and Table E-2 (p. 152) show the quality grade definitions. Refer to Foken et al. (2012) for more details. See EasyFlux DL CR6OP or CR1KXOP, Appendix F, for more details on the implementation in the data logger program.
Table E-1: Grades of relative non-stationarity, relative integral turbulence characteristics, and wind direction in the sonic instrument coordinate system
RNcov ITCsw and ITCtau wnd_dir_sonic
Relative non-stationarity (Foken et al. 2012, Model 2.3)
Relative integral turbulence characteristics
(Foken et al. 2012, Model 2.5) Wind direction
Grade Range (%) Grade Range (%) Grade Range ()
1 (highest) [0 , 15) 1 (highest) [0 , 15) 1 (highest) [0 , 150) and [210 , 360]
2 [15 , 30) 2 [15 , 30) 2 [150 , 170) and [190 , 210)
3 [30 , 50) 3 [30 , 50) 3 (lowest) [170 , 190)
4 [50 , 75) 4 [50 , 75)
5 [75 , 100) 5 [75 , 100)
6 [100 , 250) 6 [100 , 250)
7 [250 , 500) 7 [250 , 500)
8 [500 , 1,000) 8 [500 , 1,000)
9 (lowest) 1,000 9 (lowest) 1,000
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Table E-2: Overall grades for each flux variable by the grades of relative non-stationary, relative integral turbulence characteristics, and wind direction in the sonic instrument coordinate system1/
Overall quality grade
RNcov ITCsw wnd_dir_sonic
Relative non- stationarity
Relative integral turbulence characteristic
Wind direction
1 (best) 1 1 2 1
2 2 1 2 1
3 1 2 3 4 1
4 3 4 1 2 1
5 1 4 3 5 1
6 5 5 2
7 6 6 2
8 7 8 7 8 2
9 (worst) 9 9 3 1/Simplified Table 4.5 in Foken et al. (2012).
CPEC306/310 Closed-Path Eddy-Covariance Systems 152
Appendix F. Using Swagelok fittings This appendix gives a few tips on using Swagelok tube fittings. For more information, consult your local Swagelok dealer or visit their website at www.swagelok.com .
General notes
l Do not use fitting components from other manufacturers they are not interchangeable with Swagelok fittings.
l Do not attempt to use metric fittings. For example, 6 mm is very close to 1/4 in, but they are not interchangeable. Metric fittings can be identified by the stepped shoulder on the nut and on the body hex.
l Make sure that the tubing rests firmly on the shoulder of the fitting body before tightening the nut.
l Never turn the fitting body. Instead, hold the fitting body and turn the nut. l Keep tubing and fittings clean. Always use caps and plugs to keep dirt and debris out. l Do not overtighten fittings, as doing so will damage the threads.
If a nut cannot be easily tightened by hand, this indicates the threads have been damaged. Replace any damaged nuts and fittings.
F.1 Assembly The first time a Swagelok fitting is assembled, the ferrules become permanently swaged onto the tube. Assembly instructions vary depending on plastic or metal tubing. The assembly instructions are also slightly different for an initial installation than for subsequent reassembly.
First-time assembly, plastic tubing
1. Cut the tubing to length.
2. Make sure the cut is square and free of burrs.
3. Some types of plastic tubing have an aluminum layer. Take care to not flatten the tube as you cut it.
CPEC306/310 Closed-Path Eddy-Covariance Systems 153
4. Push an insert into the end of the tubing.
5. Do not remove the nuts and ferrules from the fitting. Simply insert the tube into the assembled fitting until it bottoms out.
6. Rotate the nut finger-tight.
7. While holding the fitting body steady, tighten the nut one and one-quarter turns. (For 1/16-in or 1/8-in fittings, tighten the nut three-quarters of a turn.)
First-time assembly, metal tubing
Extra care is needed to avoid overtightening brass fittings when used with metal tubing. The following steps apply to reducers and port connectors as well as metal tubing.
NOTE: No insert is required with metal tubing.
1. Do not remove the nuts and ferrules from the fitting. Simply insert the tube into the assembled fitting until it bottoms out.
2. Rotate the nut finger-tight.
3. While holding the fitting body steady, tighten the nut until it feels tight. This will normally be less than one full turn. Tightening a full one and one-quarter turns will damage the threads on the fitting and nut.
Reassembly, plastic or metal tubing
You may disassemble and reassemble Swagelok tube fittings many times, but the assembly process is slightly different than the first assembly.
1. Insert the tube with pre-swaged ferrules into the fitting until the front ferrule seats against the fitting body.
2. Rotate the nut finger-tight.
3. While holding the fitting body steady, tighten the nut slightly with a wrench.
F.2 Common replacement parts Tubing
Campbell Scientific can provide several types and sizes of plastic tubing as shown in Table F-1 (p. 155). A tubing cutter can be used to cut these tubes.
CPEC306/310 Closed-Path Eddy-Covariance Systems 154
Table F-1: Available plastic tubing sizes, construction, and usage guidelines
Tubing type
OD (in)
ID (in)
Length (ft) Construction Notes
Synflex 1300
1/4 0.17 500 Black HDPE jacket, overlapped aluminum tape, ethylene copolymer liner
Aluminum layer limits diffusion; best for sample tubes
3/8 1/4 250
1/2 3/8 250
LLDPE 3/8 1/4 500 Black linear low-density
polyethylene More flexible than HDPE 1/2 3/8 500
HDPE 5/8 1/2 100 Black high-density polyethylene Required for larger diameter
Tubing inserts
Inserts are recommended for use in plastic tubing. These inserts become permanently attached to the tubing at the first assembly, so spare inserts may be needed for replacing the ends of tubing.
Figure F-1. Swagelok insert
Table F-2: Dimensions and part numbers for Swagelok inserts
Tubing OD (in) Tubing ID (in) Swagelok part number
1/4 1/8 B-405-2
1/4 0.17 B-405-170
1/4 3/16 B-405-3
3/8 1/4 B-605-4
1/2 3/8 B-815-6
5/8 1/2 B-1015-8
CPEC306/310 Closed-Path Eddy-Covariance Systems 155
Ferrules
Each Swagelok fitting comes assembled with the front and back ferrules included. These ferrules are permanently swaged onto the tubing at the first assembly, so spare ferrules may be needed for replacing the ends of tubing.
Back ferrule Front ferrule
Figure F-2. Front and back Swagelok ferrules
Table F-3: Dimensions and part numbers for Swagelok ferrules
Tubing OD (in) Swagelok part number (front/back)
1/8 B-203-1/B-204-1
1/4 B-403-1/B-404-1
3/8 B-603-1/B-604-1
1/2 B-813-1/B-814-1
5/8 B-1013-1/B-1014-1
Plugs
Swagelok plugs are used to plug a fitting when its tube is disconnected. It is strongly recommended to plug all fittings to keep them clean. Spare plugs may be needed if they become lost or damaged.
Figure F-3. Swagelok plug
CPEC306/310 Closed-Path Eddy-Covariance Systems 156
Table F-4: Dimensions and part numbers for Swagelok plugs
Tubing OD (in) Swagelok part number
1/8 B-200-P
1/4 B-400-P
3/8 B-600-P
1/2 B-810-P
5/8 B-1010-P
Caps
Swagelok caps are used to cap the end of tubes when they are disconnected from the fitting. It is strongly recommended to cap all disconnected tubes to keep them clean. Spare caps may be needed if they become lost or damaged.
Figure F-4. Swagelok cap
Table F-5: Dimensions and part numbers for Swagelok caps
Tubing OD (in) Swagelok part number
1/8 B-200-C
1/4 B-400-C
3/8 B-600-C
1/2 B-810-C
5/8 B-1010-C
CPEC306/310 Closed-Path Eddy-Covariance Systems 157
Appendix G. CPEC310 scrub module installation, operation, and maintenance The CPEC310 scrub module provides a stream of air that has been scrubbed of CO2 and H2O and is used for zeroing the EC155. The module is housed in a fiberglass enclosure that can generally be mounted to the same structure as the CPEC310 system enclosure. The enclosure is shown in Figure G-1 (p. 158), and the specifications can be found in Scrub module specifications (p. 159).
Figure G-1. CPEC310 scrub module
G.1 Theory of operation The CPEC310 scrub module provides an air stream with CO2 and H2O removed to zero the EC155. It includes a small diaphragm pump to push the zero air to the analyzer and three bottles containing a molecular sieve to remove CO2 and water vapor from ambient air. The pump provides approximately 1.5 LPM flow. It has a heater and fan to keep it within its operating range (5 to 50 C) over ambient temperatures down to 30 C. The CPEC310 scrub module is intended to replace the cylinder of compressed zero air.
CPEC306/310 Closed-Path Eddy-Covariance Systems 158
The CPEC310 scrub module pump pulls ambient air through three bottles of molecular sieve and pushes it to the valve module. The ambient air inlet and zero air outlet fittings are on the bottom of the enclosure. It uses a small diaphragm pump that is mounted in an insulated, temperature- controlled box inside the weather-tight fiberglass enclosure.
The following are descriptions of the operating parameters of the scrub pump.
Pump control
The pump is turned on automatically when the Zero Air valve is selected. The pump has a maximum flow rate of approximately 2.0 LPM and a maximum pressure rise of approximately 90 kPa.
Scrub pump outlet pressure
The measured outlet pressure of the pump is reported in public variable scrub_press. This pressure will normally be 1 to 23 kPa when it is running.
Scrub pump temperature
The temperature of the scrub pump is reported in public variable scrub_tmpr. The operating range of the pump is 5 to 50 C. If the scrub temperature is within the operating range, the public variable scrub_tmpr_ok will be set to True. If the scrub pump temperature is outside this range, the CPEC310 will disable the pump, and the public variable scrub_tmpr_ok will be set to False. The scrub pump module has a heater (drawing 8W while operating) that turns on if the pump temperature falls below 7 C. If the CPEC310 is started at cold temperature, it may take up to 20 minutes to warm the scrub pump module (from 30 to 5 C). When it reaches 7 C the heater will cycle on/off as needed to maintain this temperature.
The scrub pump module has a fan (drawing 0.7 W while operating) that turns on if the pump temperature rises above 45 C. The fan will stay on until the scrub pump temperature falls below 40 C.
G.2 Scrub module specifications Operating temperature: 30 to 50 C
Power consumption1/
Quiescent: 0 W
With pump on: 2 W
With heater on: 8 W
With fan on: 0.7 W 1/The typical average power consumption is generally negligible in a CPEC310 system because it is used for a short time each day.
CPEC306/310 Closed-Path Eddy-Covariance Systems 159
G.3 Installation Numerous mounting options for the scrub module exist, including tripod (mast or leg), tower, or pole. Enclosure mounts are specified when ordering the CPEC310 scrub module, and mounting the module is accomplished in the same way as mounting other CPEC310 enclosures as described in Mounting (p. 24).
Connect the scrub module cable to the CPEC310 system enclosure receptacle marked Scrub Module. Remove the Swagelok plugs from the inlet and outlet and store them in the mesh pocket in the door. Install the Swagelok nut with screen on the Ambient Air inlet. Connect a 1/4-in OD tube from scrub module to valve module on the Zero inlet. Remove the desiccant pack from its plastic bag and place the pack in the mesh pocket.
Edit the CPEC310 CRBasic program to set constant CPEC310SCRUB = True and recompile.
The CPEC310 program will add the appropriate variables. It will control the temperature of the scrub module whenever it controls the temperature of the valve module. It will turn on the scrub module pump whenever the Zero Air valve is selected. The scrub module will push a flow of ambient air that has been scrubbed of CO2 and water through the valve module to the EC155.
G.4 Maintenance Once per year, refill the first bottle with fresh molecular sieve (molecular sieve 13X, 1.6 to 2.5 mm beads) according to the following steps:
1. Power down the CPEC310 or unplug the scrub module cable from the CPEC310. This will ensure the scrub module pump does not turn on while you replace the molecular sieve.
CPEC306/310 Closed-Path Eddy-Covariance Systems 160
2. Open the door of the scrub module enclosure to expose the bottles containing the molecular sieve as shown in Figure G-2 (p. 161).
Figure G-2. CPEC310 scrub module interior
3. Disconnect the fully exposed black tube (S-shaped and tied to the center of the cover as shown in Figure G-2 [p. 161]) at both ends. This tube remains captive to the cover plate.
NOTE: Disconnecting this tube ensures the bottles are not pressurized when the cover is removed. The scrub module has been designed to require this tube to be disconnected before removing the cover as a safety precaution.
CPEC306/310 Closed-Path Eddy-Covariance Systems 161
4. Loosen the four thumbscrews (shown in Figure G-2 [p. 161]) and remove the cover plate to gain access to the bottles (Figure G-3 [p. 162]). Note that the thumb screws are captive; they remain attached to the cover plate.
Figure G-3. Interior of CPEC310 scrub module with tubing and cover removed
5. Disconnect the remaining tubes from the bottles at the Swagelok fittings.
NOTE: Caps are spring loaded!
6. Remove the center bottle from the scrub module and set it aside.
7. Remove the left bottle and place it in the center position.
8. Remove the right bottle and place it in the left position.
CPEC306/310 Closed-Path Eddy-Covariance Systems 162
9. Refill the bottle that was removed by twisting while pulling to remove the top cap. The caps are held in place by friction only and the spring inside the bottle may eject the cap.
Figure G-4. Empty bottle showing the top (on the right with spring) and bottom (left) caps
10. Remove and discard of the spent molecular sieve in accordance with local ordinances and the manufacturer Safety Data Sheet.
11. Refill the bottle with new molecular sieve and replace the top cap (the cap with the spring).
12. Replace the freshly filled bottle in the open position on the right side of the enclosure.
13. Reconnect the tubes to the bottles.
14. Replace the cover plate and retighten the thumb screws.
15. Reconnect the black tube in its original location over the cover plate.
16. Close the scrub module enclosure.
17. Reconnect the scrub module cable as in Installation (p. 160) and restart the CPEC310.
CPEC306/310 Closed-Path Eddy-Covariance Systems 163
Appendix H. References Burgon, R.P., Jr., S. Sargent, T. Zha, and X. Jia. 2015. Field performance verification of carbon
dioxide, water, and nitrous oxide closed-path eddy covariance systems with vortex intakes. AGU Fall Meeting Abstracts, San Francisco, CA, USA, 1418 December 2015, B33C0669.
Foken, T., R. Leuning, S.R. Oncley, M. Mauder, and M. Aubinet. 2012. Correction and Data Quality Control. In Eddy Covariance: A Practical Guide to Measurement and Data Analysis, edited by Aubinet, M., T. Vesala, and D. Papale, 85131. New York: Springer.
Foken, T., M. Gockede, M. Mauder, L. Mahrt, B. Amiro, and W. Munger. 2004. Post-Field Data Quality Control. In Handbook of Micrometeorology: A Guide for Surface Flux Measurement and Analysis, edited by Lee, X., W. Massman, and B. Law, 181208. Dordrecht: Kluwer Academic Publishers.
Geankoplis, C.J. 1993. Transportation Processes and Unit Operation, 3rd edition. New Jersey: PTR Prentice Hall.
Horst, T.W. and D.H. Lenschow. 2009. Attenuation of scalar fluxes measured with spatially- displaced sensors. Boundary-Layer Meteorology 130: 275300.
Ibrom, A., E. Dellwik, H. Flyvbjerg, N.O. Jensen, and K. Pilegaard. 2007. Strong low-pass filtering effects on water vapour flux measurements with closed-path eddy correlation systems. Agricultural Forest Meteorology 147, 140156. https://doi.org/10.1016/j.agrformet.2007.07.007.
Kaimal, J.C., S.F. Clifford, and R.J. Lataitis. 1989. Effect of finite sampling on atmospheric spectra. Boundary-Layer Meteorology 7: 827837.
Kljun, N., P. Calanca, M.W. Rotach, and H.P. Schmid. 2004. A simple parameterization for flux footprint predictions. Advances in Water Resources 23: 765772.
Kormann, R. and F.X. Meixner. 2001. Analytical footprint model for non-neutral stratification. Boundary-Layer Meteorology 99: 207224.
Moncrieff, J.B., J.M. Massheder, H. de Bruin, J.A. Elbers, T. Friborg, B. Heusinkveld, P. Kabat, S. Scott, H. Soegaard, and A. Verhoef. 1997. A system to measure surface fluxes of momentum, sensible heat, water vapour and carbon dioxide. Journal of Hydrology 188-189: 589611.
Montgomery, R.B. 1947. Viscosity and thermal conductivity of air and diffusivity of water vapor in air. Journal of the Atmospheric Sciences 4: 193196.
Moore, C.J. 1986. Frequency response corrections for eddy correlation systems. Boundary-Layer Meteorology 37: 1735.
CPEC306/310 Closed-Path Eddy-Covariance Systems 164
Schotanus, P.S., F.T.M. Nieuwstadt, and H.A.R. de Bruin. 1983. Temperature measurement with a sonic anemometer and its application to heat and moisture flux. Boundary-Layer Meteorology 26: 8193.
Shapland, T.M., R.L. Snyder, K.T. Paw U, and A.J. McElrone. 2014. Thermocouple frequency response compensation leads to convergence of the surface renewal alpha calibration. Agricultural and Forest Meteorology 189-190: 3647.
Tanner, C.B. and G.W. Thurtell. 1969. Anemoclinometer measurements of Reynolds stress and heat transport in the atmospheric surface layer science lab. US Army Electronics Command Atmospheric Sciences Laboratory TR ECOM 66-G22-F: R1R10.
van Dijk, A. 2002a. Extension of 3D of The effect of linear averaging on scalar flux measurements with a sonic anemometer near the surface by Kristensen and Fitzjarrald. Journal of Atmospheric and Oceanic Technology 19: 8082.
van Dijk, A. 2002b. The Principle of Surface Flux Physics. Research Group of the Royal Netherlands Meteorological Institute and Department of Meteorology and Air Quality with Agricultural University Wageningen.
Wilczak, J.M., S.P. Oncley, and S.A. Stage. 2001. Sonic anemometer tilt correction algorithm. Boundary-Layer Meteorology 99: 127150.
CPEC306/310 Closed-Path Eddy-Covariance Systems 165
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Safety DANGERMANY HAZARDS ARE ASSOCIATEDWITH INSTALLING, USING, MAINTAINING, ANDWORKING ON OR AROUND TRIPODS, TOWERS, AND ANY ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC. FAILURE TO PROPERLY AND COMPLETELY ASSEMBLE, INSTALL, OPERATE, USE, ANDMAINTAIN TRIPODS, TOWERS, AND ATTACHMENTS, AND FAILURE TO HEED WARNINGS, INCREASES THE RISK OF DEATH, ACCIDENT, SERIOUS INJURY, PROPERTY DAMAGE, AND PRODUCT FAILURE. TAKE ALL REASONABLE PRECAUTIONS TO AVOID THESE HAZARDS. CHECK WITH YOUR ORGANIZATION'S SAFETY COORDINATOR (OR POLICY) FOR PROCEDURES AND REQUIRED PROTECTIVE EQUIPMENT PRIOR TO PERFORMING ANYWORK. Use tripods, towers, and attachments to tripods and towers only for purposes for which they are designed. Do not exceed design limits. Be familiar and comply with all instructions provided in product manuals. Manuals are available at www.campbellsci.com. You are responsible for conformance with governing codes and regulations, including safety regulations, and the integrity and location of structures or land to which towers, tripods, and any attachments are attached. Installation sites should be evaluated and approved by a qualified engineer. If questions or concerns arise regarding installation, use, or maintenance of tripods, towers, attachments, or electrical connections, consult with a licensed and qualified engineer or electrician. General
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