CPEC300/306/310
Covariance Systems
Closed-Path Eddy-
10/18
Copyright © 2018
Campbell Scientific, Inc.
Limited Warranty
“Products manufactured by CSI are warranted by CSI to be free from defects in
materials and workmanship under normal use and service for twelve months
from the date of shipment unless otherwise specified in the corresponding
product manual. (Product manuals are available for review online at
www.campbellsci.com.) Products not manufactured by CSI, but that are resold
by CSI, are warranted only to the limits extended by the original manufacturer.
Batteries, fine-wire thermocouples, desiccant, and other consumables have no
warranty. CSI’s obligation under this warranty is limited to repairing or
replacing (at CSI’s option) defective Products, which shall be the sole and
exclusive remedy under this warranty. The Customer assumes all costs of
removing, reinstalling, and shipping defective Products to CSI. CSI will return
such Products by surface carrier prepaid within the continental United States of
America. To all other locations, CSI will return such Products best way CIP
(port of entry) per Incoterms ® 2010. This warranty shall not apply to any
Products which have been subjected to modification, misuse, neglect, improper
service, accidents of nature, or shipping damage. This warranty is in lieu of all
other warranties, expressed or implied. The warranty for installation services
performed by CSI such as programming to customer specifications, electrical
connections to Products manufactured by CSI, and Product specific training, is
part of CSI's product warranty. CSI EXPRESSLY DISCLAIMS AND
EXCLUDES ANY IMPLIED WARRANTIES OF MERCHANTABILITY
OR FITNESS FOR A PARTICULAR PURPOSE. CSI hereby disclaims,
to the fullest extent allowed by applicable law, any and all warranties and
conditions with respect to the Products, whether express, implied or
statutory, other than those expressly provided herein.”
Assistance
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served by Campbell Scientific, Inc. directly. Affiliate companies handle repairs
for customers within their territories. Please visit www.campbellsci.com to
determine which Campbell Scientific company serves your country.
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CAMPBELL SCIENTIFIC, INC., phone (435) 227-9000. Please write the
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CAMPBELL SCIENTIFIC, INC.
RMA#_____
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For all returns, the customer must fill out a “Statement of Product Cleanliness
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customer’s expense. Campbell Scientific reserves the right to refuse service on
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concerns for our employees.
Safety
DANGER — MANY HAZARDS ARE ASSOCIATED WITH INSTALLING, USING, MAINTAINING, AND WORKING 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, AND MAINTAIN 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 ANY WORK.
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 or by
telephoning (435) 227-9000 (USA). 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
• Prior to performing site or installation work, obtain required approvals and permits. Comply
with all governing structure-height regulations, such as those of the FAA in the USA.
• Use only qualified personnel for installation, use, and maintenance of tripods and towers, and
any attachments to tripods and towers. The use of licensed and qualified contractors is highly
recommended.
• Read all applicable instructions carefully and understand procedures thoroughly before
beginning work.
• Wear a hardhat and eye protection, and take other appropriate safety precautions while
working on or around tripods and towers.
• Do not climb tripods or towers at any time, and prohibit climbing by other persons. Take
reasonable precautions to secure tripod and tower sites from trespassers.
• Use only manufacturer recommended parts, materials, and tools.
Utility and Electrical
• You can be killed or sustain serious bodily injury if the tripod, tower, or attachments you are
installing, constructing, using, or maintaining, or a tool, stake, or anchor, come in contact with
overhead or underground utility lines.
• Maintain a distance of at least one-and-one-half times structure height, 20 feet, or the distance
required by applicable law, whichever is greater, between overhead utility lines and the
structure (tripod, tower, attachments, or tools).
• Prior to performing site or installation work, inform all utility companies and have all
underground utilities marked.
• Comply with all electrical codes. Electrical equipment and related grounding devices should be
installed by a licensed and qualified electrician.
Elevated Work and Weather
• Exercise extreme caution when performing elevated work.
• Use appropriate equipment and safety practices.
• During installation and maintenance, keep tower and tripod sites clear of un-trained or non-
essential personnel. Take precautions to prevent elevated tools and objects from dropping.
• Do not perform any work in inclement weather, including wind, rain, snow, lightning, etc.
Maintenance
• Periodically (at least yearly) check for wear and damage, including corrosion, stress cracks,
frayed cables, loose cable clamps, cable tightness, etc. and take necessary corrective actions.
• Periodically (at least yearly) check electrical ground connections.
WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL SCIENTIFIC PRODUCTS,
THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER INSTALLATION, USE, OR
MAINTENANCE OF TRIPODS, TOWERS, OR ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS,
ENCLOSURES, ANTENNAS, ETC.
Table of Contents
PDF viewers: These page numbers refer to the printed version of this document. Use the
PDF reader bookmarks tab for links to specific sections.
1. Introduction ................................................................ 1
2. Precautions ................................................................ 2
3. Initial Inspection ........................................................ 2
4. Overview .................................................................... 2
4.1 CPEC300/306/310 System Components ..............................................3
4.1.1 EC100 Electronics.........................................................................3
4.1.2 EC155 Gas Analyzer .....................................................................3
4.1.3 CSAT3A Sonic Anemometer Head ..............................................4
4.1.4 Pump Module ................................................................................5
4.2 CPEC300 ..............................................................................................5
4.3 CPEC306 ..............................................................................................7
4.4 CPEC310 ............................................................................................ 10
4.5 Other Components ............................................................................. 12
4.5.1 CR6 Datalogger .......................................................................... 12
4.6 Optional Components ......................................................................... 13
4.6.1 CDM-A116 ................................................................................. 13
4.6.2 CPEC310 Scrub Module ............................................................. 13
4.7 Other Components ............................................................................. 14
4.7.1 Carrying Cases ............................................................................ 14
4.7.2 Enclosure Mounting Options ...................................................... 15
4.8 Common Accessories ......................................................................... 15
4.9 Support Software ................................................................................ 16
4.10 Replacement Parts .............................................................................. 17
4.11 Theory of Operation ........................................................................... 19
4.11.1 EC155 Gas Analyzer ................................................................... 19
4.11.2 CSAT3A Sonic Anemometer Head ............................................ 19
4.11.3 Valve Module – CPEC310 .......................................................... 20
4.11.4 CPEC300-Series Pump Module .................................................. 22
4.12 Specifications ..................................................................................... 23
5. Installation ............................................................... 24
5.1 Mounting ............................................................................................ 24
5.1.1 Support Structure ........................................................................ 24
5.1.2 Mount Enclosures ....................................................................... 24
5.1.3 Install EC Sensors ....................................................................... 25
5.2 Plumbing ............................................................................................ 27
5.2.1 Pump Module .............................................................................. 28
5.2.2 Zero/Span with the CPEC310 ..................................................... 28
5.3 Wiring ................................................................................................ 30
5.3.1 Ground Connections ................................................................... 30
5.3.2 EC Sensor Cables ........................................................................ 31
5.3.3 Pump Module Cable for a CPEC300 .......................................... 33
5.3.4 Apply Power ............................................................................... 33
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Table of Contents
6. Configure the EasyFlux DL Program ..................... 34
6.1 Operation ............................................................................................ 36
6.2 Set Constants ...................................................................................... 36
6.2.1 Categories of Constants .............................................................. 36
6.2.2 Accessing the Constants .............................................................. 37
6.3 Edit Input Variables ........................................................................... 43
6.4 Data Retrieval .................................................................................... 54
6.5 Output Tables ..................................................................................... 55
6.6 Program Sequence of Measurement and Corrections ......................... 79
7. Zero and Span .......................................................... 80
7.1 User-Initiated Zero/Span for CPEC310 ............................................. 84
7.1.1 CPEC310 Auto Zero/Span .......................................................... 84
7.1.2 CPEC310 Manual H2O Span ...................................................... 86
7.2 User-Initiated Manual Zero/Span for CPEC300 or CPEC306 ........... 87
7.2.1 CPEC300/CPEC306 Manual Zero .............................................. 87
7.2.2 CPEC300/CPEC306 Manual CO2 Span ...................................... 88
7.2.3 CPEC300/CPEC306 Manual H2O Span ..................................... 88
8. Maintenance and Troubleshooting ......................... 89
8.1 Enclosure Desiccant ........................................................................... 89
8.2 EC155 Windows ................................................................................ 89
8.3 EC155 Molecular Sieve Bottles ......................................................... 90
8.4 Pump Module Filter ........................................................................... 90
8.5 Testing Wind Offset ........................................................................... 90
9. Repair ....................................................................... 90
Appendices
A. EasyFlux DL CR6CP Process Flow ...................... A-1
B. Sampling Site, Regime, and Mode ........................ B-1
C. Wiring the CR6 and Optional Energy Balance
Sensors ................................................................ C-1
C.1 Overview .......................................................................................... C-1
C.1.1 IRGA and Sonic Anemometer .................................................. C-1
C.1.2 CDM-A116 Module (CPEC306 and CPEC310 only) ............... C-2
C.1.3 GPS Receiver ............................................................................ C-2
C.1.4 Fine-Wire Thermocouple .......................................................... C-2
C.1.5 Temperature and Relative Humidity Probe ............................... C-3
C.1.6 Radiation Measurements Option 1 ............................................ C-3
C.1.7 Radiation Measurements Option 2 ............................................ C-4
C.18 Precipitation Gage ..................................................................... C-6
C.19 Soil Temperature ....................................................................... C-6
C.1.10 Soil Water Content .................................................................... C-7
C.1.11 Soil Heat Flux Plates ................................................................. C-8
C.1.12 Self-Calibrating Soil Heat Flux Plates ...................................... C-8
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Table of Contents
D. System Diagnostic Word....................................... D-1
E. Quality Grading ....................................................... E-1
F. CPEC300 Series Diagnostics ................................. F-1
F.1 Status Text Variables ....................................................................... F-1
F.2 Status Boolean Variables ................................................................. F-6
F.3 CPEC300 System Diagnostic Words ............................................... F-8
G. Public Variables ..................................................... G-1
H. Output Variables .................................................... H-1
I. Control Bits .............................................................. I-1
J. Using Swagelok Fittings ........................................ J-1
J.1 Assembly ........................................................................................... J-1
J.2 Common Replacement Parts ............................................................. J-2
K. CPEC310 Scrub Module Installation, Operation,
and Maintenance ................................................. K-1
K.1 Theory of Operation ........................................................................ K-1
K.2 Scrub Module Specifications .......................................................... K-2
K.3 Installation ....................................................................................... K-2
K.4 Maintenance .................................................................................... K-3
L. CPEC300 Series Pump Replacement .................... L-1
L.1 Introduction ...................................................................................... L-1
L.2 Removal ........................................................................................... L-1
L.3 Installation ........................................................................................ L-6
Figures
4-1. EC100 electronics module ...................................................................3
4-2. EC155 closed-path CO2/H2O gas analyzer .........................................4
4-3. CSAT3A sonic anemometer .................................................................4
4-4. CPEC300 system ..................................................................................5
4-5. CPEC300 enclosure .............................................................................6
4-6. CPEC300 enclosure with EC100 electronics and CR6 ........................6
4-7. CPEC300 pump module .......................................................................7
4-8. CPEC306 system ..................................................................................8
4-9. CPEC306 system enclosure .................................................................9
4-10. Interior of CPEC306 system enclosure ................................................9
4-11. Fully configured CPEC310 system .................................................... 10
4-12. CPEC310 system enclosure ............................................................... 11
4-13. Interior of CPEC310 system enclosure .............................................. 11
4-14. CPEC310 valve module ..................................................................... 12
4-15. CR6 measurement and control datalogger ......................................... 12
4-16. CDM-A116 ........................................................................................ 13
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Table of Contents
4-17. CPEC310 scrub module enclosure ..................................................... 14
4-18. CPEC310 scrub module (shown with enclosure lid open) ................. 14
4-19. USB memory card reader/writer ........................................................ 16
4-20. Vortex filter for EC155 intake ........................................................... 17
4-21. Sonic wick spares kit .......................................................................... 17
4-22. Single desiccant pack ......................................................................... 18
4-23. Humidity indicator card ..................................................................... 18
4-24. Diaphragm pump used in CPEC300-series systems .......................... 19
4-25. EC155 gas analyzer ............................................................................ 19
4-26. CSAT3A sonic anemometer head ...................................................... 20
5-1. CM210 mounting bracket on a tripod mast ........................................ 26
5-2. Mounting of EC155 and CSAT3A ..................................................... 26
5-3. Plumbing connections for CPEC300 .................................................. 27
5-4. Plumbing connections for CPEC306 .................................................. 27
5-5. Plumbing for CPEC310 with optional scrub module ......................... 28
5-6. Connecting pump tube from EC155 analyzer to pump module ......... 30
5-7. Enclosure and tripod grounded to a copper-clad grounding rod ........ 30
5-8. EC155 and CSAT3A electrical connections; mounting hardware
and tubing not shown) .................................................................... 31
5-9. Wiring the EC100 to a CPEC306 and CPEC310 enclosure ............... 32
5-10. Wiring to EC100 electronics .............................................................. 33
5-11. CPEC300 splicing switches ............................................................... 34
6-1. Example screen from CRBasic Editor showing user-defined
configuration constants ................................................................... 39
6-2. Custom keypad menu; arrows indicate submenus .............................. 47
J-1. Swagelok insert ................................................................................. J-3
J-2. Front and back Swagelok ferrules ..................................................... J-3
J-3. Swagelok plug ................................................................................... J-4
J-4. Swagelok cap .................................................................................... J-4
K-1. CPEC310 scrub module .................................................................. K-1
K-2. CPEC310 scrub module interior...................................................... K-3
K-3. Interior of CPEC310 scrub module with tubing and cover
removed ....................................................................................... K-4
K-4. Empty bottle showing the top (on the right with spring) and
bottom (left) caps ......................................................................... K-5
L-1. Four screws holding filter assembly inside CPEC300 pump
module enclosure .......................................................................... L-1
L-2. Upright filter unit in enclosure ......................................................... L-2
L-3. Location of #4 screws of pump assembly ........................................ L-2
L-4. Exposed CPEC300 pump assembly ................................................. L-3
L-5. Removal of original pump module inner plate and replacement
with new inner plate provided in pump replacement kit ............... L-3
L-6. New inner plate with adhesive tape .................................................. L-4
L-7. New inner plate placement on pump module cover ......................... L-4
L-8. Location of pump connector in CPEC300 pump electronics ........... L-5
L-9. Self-tapping screws attaching pump to metal box ............................ L-5
L-10. Location of cuts to remove pump assembly from tubing ................. L-6
L-11. Inlet and outlet tubing reconnected to pump .................................... L-6
L-12. Pump side with inlet and outlet tubing connected ............................ L-7
L-13. Proper positioning of CPEC300 in shell cover ................................. L-7
Tables
5-1. SDM Wiring ....................................................................................... 31
6-1. Program Constants ............................................................................. 40
6-2. Variables from Initial Configuration Menu ....................................... 48
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Table of Contents
6-3. Variables and Settings in Site Var Settings Menu .............................. 50
6-4. Variables from the Run Station Menu ................................................ 54
6-5. microSD Flash Card Fill Times ......................................................... 55
6-6. Data Output Tables ............................................................................ 56
6-7. Data Fields in the Time_Series Data Output Table ............................ 57
6-8. Data Fields in the Diagnostic Output Table ....................................... 58
6-9. Data Field in the EC100_Config_Notes Output Table ....................... 59
6-10. Data Fields in the Flux_AmeriFluxFormat Output Table .................. 60
6-11. Data Fields in the Flux_CSFormat Data Output Table ...................... 63
6-12. Data fields in the Flux_Notes Output Table ....................................... 68
6-13. Data Fields in the Zero_Span_Notes Table ........................................ 77
6-14. Data Field in the System_Operatn_Notes Output Table .................... 79
7-1. Variables Found in Menus for Zero and Span.................................... 81
7-2. Site Sequence and Timing in the Auto Zero and Span Cycle............. 85
B-1. Site Numbers, Text Descriptors, and Descriptions .......................... B-1
B-2. Mode Names and Descriptions ........................................................ B-2
C-1. Default Wiring for IRGA and Sonic Anemometer ........................... C-1
C-2. Default Wiring for GPS Receiver .................................................... C-2
C-3. Default Wiring for Fine-Wire Thermocouple .................................. C-3
C-4. Default Wiring for Temperature and Relative Humidity Probe ....... C-3
C-5. Default Wiring for Radiation Measurement Option 1 ...................... C-4
C-6. Default Wiring for Radiation Measurements Option 2 .................... C-5
C-7. Default Wiring for Precipitation Gage ............................................. C-6
C-8. Default Wiring for Soil Thermocouple Probes ................................ C-6
C-9. Default Wiring for Soil Water Content Probes ................................ C-7
C-10. Default Wiring for Non-Calibrating Soil Heat Flux Plates .............. C-8
C-11. Default Wiring for Soil Heat Flux Plates (Self Calibrating). ........... C-9
D-1. Description of Bits for System Diagnostic Word. ........................... D-1
E-1. Grades of relative non-stationarity, relative integral turbulence
characteristics, and wind direction in the sonic instrument
coordinate system. ........................................................................ E-1
E-2. Overall grades for each flux variable by the grades of relative
non-stationary, relative integral turbulence characteristic, and
wind direction in sonic instrument coordinate system. ................. E-2
F-1. Summary CPEC300 diagnostic flags encoded in diag_cpec ............ F-9
G-1. CPEC300 public variables .............................................................. G-1
H-1. Values stored in table ts_data .......................................................... H-1
H-2. Values stored in table flux ............................................................... H-3
H-3. Values stored in table zero_ span .................................................... H-6
H-4. Values stored in table message_log................................................. H-9
H-5. Values stored in table config_history ............................................ H-10
I-1. CPEC300 temperature control bits encoded in ControlBits .............. I-1
J-1. Available plastic tubing sizes, construction, and usage guidelines ... J-2
J-2. Dimensions and part numbers for Swagelok inserts ......................... J-3
J-3. Dimensions and part numbers for Swagelok ferrules ........................ J-3
J-4. Dimensions and part numbers for Swagelok plugs ........................... J-4
J-5. Dimensions and part numbers for Swagelok caps ............................. J-5
v
NOTE
CPEC300/306/310 Closed-Path
Eddy-Covariance Systems
1. Introduction
The CPEC300, CPEC 306, and CPEC310 (denoted as CPEC300 series from
this point forward) are closed-path, eddy-covariance (CPEC) flux systems that
are used for long-term monitoring of atmosphere–biosphere exchanges of
carbon dioxide, water vapor, heat, and momentum. The series replaces
Campbell Scientific’s CPEC200 which was a complete, turn-key system that
included a closed-path gas analyzer (EC155), a sonic anemometer head
(CSAT3A), datalogger (CR3000), sample pump, and optional valve module for
automated zero and span.
The CPEC300 series provides users with three options that cater to various
eddy covariance applications. All CPEC 300 systems use a CR6 datalogger and
the closed-path version of EasyFlux™ DL for automated post-processing flux
calculations.
The CPEC series is available as three systems:
• CPEC300 – a compact system with pump module
• CPEC306 – a mid-level, expandable system with pump module
• CPEC310 – an expandable system with pump module and three-
valve, zero-and-span module
This manual discusses three separate instrument packages that
have been developed to better address a wide variety of user needs.
The three instrument packages are the CPEC300, CPEC306, and
CPEC310. Throughout the manual, when the section being
discussed applies to all three systems, the systems will be referred
to collectively as the CPEC300 series. Where the manual
discusses specifics that are unique to one or two of the systems,
they will be named specifically as a CPEC300, CPEC306, or
CPEC310.
Before using any of the CPEC300-series instruments configurations, please
study:
• Section 2, Precautions
• Section 3, Initial Inspection
• Section 5, Installation
Operational instructions critical to the preservation of the system are found
throughout this manual. Before using a CPEC300 series, please study the entire
manual. Further information pertaining to the CPEC300 series can be found in
the Campbell Scientific publication EC155 CO
Analyzer Manual, available at www.campbellsci.com.
(p. 2)
(p. 24)
(p. 2)
and H2O Closed-Path Gas
2
1
2. Precautions
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Other manuals that may be helpful include:
• CR6 ProductManual
• CSAT3 Three Dimensional Sonic Anemometer Manual
• LoggerNet Instruction Manual
• ENC10/12, ENC16/18 Instruction Manual
• CM106 Tripod Instruction Manual
• Tripod Installation Manual Models CM110, CM115, CM120
• WARNING:
o 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.
o Grounding electrical components in the measurement system is
critical. Proper earth (chassis) grounding will ensure maximum
electrostatic discharge (ESD) protection and higher measurement
accuracy.
o Use care when connecting and disconnecting tube fittings to
avoid introducing dust or other contaminants.
o Do not overtighten the tube fittings. Consult Appendix J, Using
Swagelok Fittings
o A power source for a CPEC300-series system should be designed
thoughtfully to ensure uninterrupted power. If needed, contact
Campbell Scientific for assistance.
o Retain all spare caps and plugs as these are required when
shipping or storing any CPEC300-series system.
(p. J-1), for information on proper connection.
3. Initial Inspection
Upon receipt of a CPEC300-series system, inspect the packaging and contents
for damage. File damage claims with the shipping company.
Verify receipt of all components of the CPEC300-series system purchased.
Model numbers are found on each product. On cables, the model number is
usually found at the connection end of the cable. Check this information
against the enclosed shipping documents to verify the expected products and
the correct lengths of cable are included.
4. Overview
The CPEC300, CPEC306, and CPEC310 are three closely related closed-path,
eddy-covariance (EC) systems that are used for long-term monitoring of
atmosphere–biosphere exchanges of carbon dioxide, water vapor, heat, and
momentum. The CPEC300 is a basic, entry level system, the CPEC306 is a
mid-level, expandable system, and the CPEC310 is the high-end, expandable
system.
The CPEC306 and CPEC310 have options for a CDM-A116 that allows for
additional sensors for energy-balance and meteorological measurements. The
CPEC310 is equipped with a three-valve module to allow automatic zero-andspan.
2
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Each system comes as a complete, standalone system consisting of Campbell’s
EC100 electronics module, closed-path gas analyzer (EC155), sonic
anemometer (CSAT3A), and sample pump. Systems are wired for a CR6
datalogger that can be purchased with the system or wired by users that already
have a CR6 datalogger. Section 4.1, CPEC300/306/310 System Components
(p. 3), describe the basic components of all three systems. Section 4.2, CPEC300
(p. 5), Section 4.3, CPEC306 (p. 7), and Section 4.4, CPEC310 (p. 10), below
describe the specifics of each individual system in greater detail.
4.1 CPEC300/306/310 System Components
The following sections describe the components that come standard with any
of the CPEC300-series systems.
4.1.1 EC100 Electronics
The EC100 electronics module (FIGURE 4-1) controls the EC155 and
CSAT3A. In the CPEC300 system, the CR6 is attached to the lid of the EC100
electronics enclosure (see Section 4.5.1, CR6 Datalogger
CPEC306 and 310 systems, the EC100 exists as a standalone enclosure. The
EC100 electronics must be mounted within 3.0 m (10.0 ft) of the EC155 and
CSAT3A.
(p. 12)). In the
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 patented
1/
U.S. Pat. No. 9,217,692
1/
vortex
3
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
intake which reduces intake maintenance, 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, is
included as part of CPEC300, CPEC306, and CPEC310 systems. For detailed
information and specifications, see the EC155 manual at
www.campbellsci.com.
FIGURE 4-2. EC155 closed-path CO2/H2O gas analyzer
4.1.3 CSAT3A Sonic Anemometer Head
The CSAT3A 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 the
separation between the instruments. In January 2016, starting with CSAT3A
serial number 2000, the mounting platform of the CSAT3A was updated. Other
changes also increased the stiffness of the head for improved long-term
accuracy of sonic temperature. For detailed information and specifications, see
the CSAT3B manual.
Campbell Scientific’s standalone sonic anemometer, the
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
4.1.4 Pump Module
All three CPEC 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 setpoint (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
that are caused by the pump.
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
4.2 CPEC300
Section 4.2, CPEC300
CPEC310
The CPEC300 is the most compact of the three systems, yet has the core
capabilities provided by the EC100 controlling the EC155 and CSAT3A, and
the measurement and control capabilities of the CR6 datalogger.
A typical configuration of the CPEC300 is shown in FIGURE 4-4.
The CPEC300 comes with two system enclosures: the CPEC300 enclosure
which houses the EC100 electronics and the CR6 datalogger (see FIGURE 4-5
and FIGURE 4-6; and the CPEC300 pump module enclosure which houses the
system pump (see FIGURE 4-7).
(p. 10), below describe each of the individual systems in greater detail.
(p. 5); Section 4.3, CPEC306 (p. 7); and Section 4.4,
FIGURE 4-4. CPEC300 system
5
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 4-5. CPEC300 enclosure
FIGURE 4-6. CPEC300 enclosure with EC100 electronics and CR6
6
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
4.3 CPEC306
FIGURE 4-7. CPEC300 pump module
The CPEC306 is a mid-level system that includes all components of the
CPEC300 but has a larger enclosure which is separate from the EC100
electronics. A typical configuration of a CPEC306 system is shown in FIGURE
4-8.
The two enclosures of the CPEC306 system are the EC100 electronics
enclosure, and datalogger and pump module enclosure. Unlike the CPEC300,
the EC100 electronics are housed separately from the datalogger (FIGURE
4-1). The CR6 datalogger is positioned within the CPEC306 enclosure
(FIGURE 4-9 and FIGURE 4-10). The CPEC306 enclosure also includes the
pump module and capacity for optional CDM-A116 modules (see Section
4.6.1, CDM-A116
(p. 13)) for energy balance and meteorological measurements.
7
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 4-8. CPEC306 system
8
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 4-9. CPEC306 system enclosure
FIGURE 4-10. Interior of CPEC306 system enclosure
9
4.4 CPEC310
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Of the three CPEC systems, the CPEC310 has the most included features. As
with the CPEC306, there is the capacity for a CDM-A116. A three-valve
module is included and 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 CO
reference tank (shown in FIGURE 4-11) and either a scrub module or a zero air
reference tank to execute the automatic zero and span. These tanks are not sold
by Campbell Scientific.
A typical CPEC310 system, including a scrub module is shown in FIGURE
4-11.
2
FIGURE 4-11. Fully configured CPEC310 system
10
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 4-12. CPEC310 system enclosure
FIGURE 4-13. Interior of CPEC310 system enclosure
11
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
The CPEC310 three-valve module (FIGURE 4-14) is housed in the CPEC310
enclosure and is used to automate zero and CO
perform a field zero and field CO
span on a user-defined interval. Field H2O
2
span checks, and automatically
2
span requires a dewpoint generator and cannot be automated because the
dewpoint generator is a laboratory instrument and not designed for the longterm field deployment necessary for the automated zero/span operation.
Therefore, H
O spans must be performed under manual control.
2
FIGURE 4-14. CPEC310 valve module
4.5 Other Components
The following section describes the CR6 datalogger that is required for any of
the CPEC300-series systems. It is purchased separately, as many users already
own the CR6 datalogger.
4.5.1 CR6 Datalogger
The CR6 and EasyFlux DL are the core of the CPEC300 systems. They are
used to store the raw data, process that data and store fluxes, allow for remote
communications to the station, and provide diagnostic information about the
system. Additionally, the CR6 (FIGURE 4-15) is used for system control of the
pump and valves.
FIGURE 4-15. CR6 measurement and control datalogger
12
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
4.6 Optional Components
The following sections describe optional components that are available to
expand the capabilities of the CPEC306 or the CPEC310. The specific
configurations will depend on specific site conditions, data requirements, and
research goals.
4.6.1 CDM-A116
The CDM-A116 (FIGURE 4-16) is a 24-bit analog input module that can
increase the capacity of analog channels in a datalogger system. The CDMA116 has 16 additional channels available. The CPEC306 and CPEC310
enclosures both allow for the addition of CDM-A116 modules.
FIGURE 4-16. CDM-A116
4.6.2 CPEC310 Scrub Module
The CPEC310 scrub module provides a source of zero air and is used for
zeroing the EC155. It consists of a pump and a three-stage molecular sieve and
connects to the CPEC300 system enclosure. The scrub module (shown in
FIGURE 4-17 and FIGURE 4-18) eliminates the need for a cylinder of zero air.
A cylinder of known CO
of the two cylinders for zero/span and is useful in locations where transporting
and replacing cylinders is inconvenient. Additional information regarding
installation and maintenance of the CPEC310 scrub module can be found in
Appendix K, CPEC310 Scrub Module Installation, Operation, and
Maintenance
(p. K-1).
is still required. The module reduces the need for one
2
13
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 4-17. CPEC310 scrub module enclosure
FIGURE 4-18. CPEC310 scrub module (shown with enclosure lid
open)
4.7 Other Components
4.7.1 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.
14
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
NOTE
4.7.2 Enclosure Mounting Options
The enclosures for any of the CPEC300-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, and the CPEC300
pump module enclosure is similar to the ENC10/12 enclosure. The same
mounting options are available and outlined below:
• Triangular tower (UT10, UT20, or UT30)
• Tripod mast 3.8 cm (1.5 in) to 4.8cm (1.9 in) diameter
• Tripod leg (CM106 or CM106K tripod only)
• Large pole 10.2 cm (4.0 in) to 25.4 cm (10.0 in) diameter
• No mounting bracket
Consult the ENC10/12, ENC16/18 Instruction Manual, available at
www.campbellsci.com, for details on mounting bracket options.
4.8 Common Accessories
There are several items that may be required to complete the installation, but
are not included in a CPEC300-series system. Some of the more common
accessories are:
System Power Cable: Two power cables are required for a CPEC300 series;
one for the main CPEC300-series system and one for the EC100 electronics.
The preferred power cable, CABLEPCBL-L, consists of a twisted red/black
pair of wire gauge (AWG) 16 within a rugged Santoprene jacket. It is cut to the
specified length and the end is finished for easy installation.
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 CPEC300 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.
Pump Tube: A tube must be used to connect the EC155 to the pump module.
If the EC155 is within 50 ft of the CPEC300-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.
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
span cylinders to the valve module of the CPEC310. Bulk tubing with an
CO
2
aluminum core (to minimize diffusion through the tubing wall) and a
15
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
UV-resistant, black, high-density polyethylene jacket can be cut to length and
installed onsite. The tubing should be of 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 CO
span cylinder is selected. One long tube is
2
required to connect the valve module to the EC155, and two short tubes are
required to connect the zero and CO
span cylinders to the valve module. Pre-
2
swaged tube assemblies are available for this purpose and are cut to a userspecified length.
USB Memory Card Reader/Writer: The USB memory card reader/writer is
shown in FIGURE 4-19. 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 4-19. USB memory card reader/writer
4.9 Support Software
There are several software products available for interfacing a computer to the
CR6 datalogger.
EasyFlux DL: EasyFlux DL 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 for Closed-Path Eddy
Covariance systems enables a CR6 datalogger to collect fully corrected fluxes
, latent heat (H2O), sensible heat, ground surface heat flux (optional),
of CO
2
and momentum from a Campbell Scientific open-path EC system with optional
energy balance sensors. The program processes the EC 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
Section 6, Configure the EasyFlux DL Program
PC200W: PC200W is a free, starter software package that provides basic tools
such as clock set, program download, monitor data, retrieve data, etc. PC200W
supports direct connections between PC and datalogger but has no
telecommunications or scheduled data-collection support.
(p. 34).
PC400: PC400 is a mid-level software package that supports a variety of
telecommunication options, manual data collection, data display, and includes
16
a full-featured CRBasic program editor. PC400 does not support combined
communication options (for example, phone-to-RF), PakBus routing, or
scheduled data collection.
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, scheduled data retrieval, or for large datalogger
networks.
4.10 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 µm particulate
filter with ¼-in Swagelok nuts on either side as shown in FIGURE 4-20.
Replace the filter when the signal strength has dropped to 0.8 or less.
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 4-20. Vortex filter for EC155 intake
Sonic Wicks: A sonic wicks spares 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 4-21).
FIGURE 4-21. Sonic wick spares kit
Silica Desiccant Bags: Silica desiccant bags (FIGURE 4-22) are used to
desiccate the CPEC300-series system enclosure and should be periodically
replaced. These can be purchased as a single, four-unit pack or as a quantity of
20.
17
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 4-22. Single desiccant pack
Humidity Indicator Card: The replacement humidity indicator card
(FIGURE 4-23) provides a visual reference of humidity level inside the
enclosure.
FIGURE 4-23. Humidity indicator card
EC155 Replacement Molecular Sieve: The EC155 has two small bottles
filled with molecular sieve to remove CO
and water vapor from inside of the
2
sensor head. Two bottles are included when purchasing the replacement.
Diaphragm Pump: The pump module for any of the CPEC300-series systems
includes a small double-head diaphragm pump with a brushless DC motor. 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 CPEC300 system enclosure. If the pump fails, a replacement pump
(FIGURE 4-24) is available. The part includes the connector for easy
installation. See Appendix L, CPEC300 Series Pump Replacement
(p. L-1), for
instructions on replacing the pump.
18
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 4-24. Diaphragm pump used in CPEC300-series systems
4.11 Theory of Operation
Any of the CPEC300-series systems can be used for long-term monitoring of
atmosphere–biosphere exchanges of carbon dioxide, water vapor, heat, and
momentum. These systems all include a closed-path gas analyzer (EC155), a
sonic anemometer head (CSAT3A), a sample pump, and are designed to work
only with a CR6 datalogger. The CR6 can be purchased with any of the three
systems or specified to be pre-wired for installation of a CR6 that the user
already has. The CPEC306 and CPEC310 allow for increased sensor capacity
with CDM-A116 modules to accommodate additional sensor measurements.
The CPEC310 comes equipped with a three-valve module for automated zero
and CO2 span of the EC155.
4.11.1 EC155 Gas Analyzer
The EC155 (FIGURE 4-25) is Campbell Scientific’s closed-path, mid-infrared
absorption gas analyzer that measures molar mixing ratios of carbon dioxide
and water vapor. More information about the operation of the EC155 can be
found in the manual, EC155 CO
www.campbellsci.com.
FIGURE 4-25. EC155 gas analyzer
4.11.2 CSAT3A Sonic Anemometer Head
The CSAT3A, as shown in FIGURE 4-26, is an ultrasonic anemometer sensor
head for measuring wind speed in three dimensions. It shares integrated
electronics, the EC100 electronics, with the EC155 gas analyzer. It is similar to
and H2O Closed-path Gas Analyzer at
2
19
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
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 u
, referenced to the anemometer head.
u
z
, uy, and
x
The CSAT3A also determines the speed of sound for each transducer pair.
These measurements are averaged and converted to sonic virtual temperature
) based on the relationship between speed of sound and air temperature. For
(T
s
more detailed information and specifications, see the CSAT3B manual,
available at www.campbellsci.com.
FIGURE 4-26. CSAT3A sonic anemometer head
4.11.3 Valve Module – CPEC310
The three-valve module, shown in FIGURE 4-14, is housed in the CPEC310
enclosure and is used to perform manual and automated zero and CO
checks, and manually and automatically perform a zero and CO
user-defined interval. As described in Section 4.4, CPEC310
requires a dewpoint generator and cannot be automated.
The CPEC310 zero and CO
they flow only when selected. This allows the zero and CO
continuously connected for automatic, unattended operation.
span
2
span on a
2
(p. 10), H
span inlets are not bypass equipped, meaning that
2
span tanks to be
2
O span
2
20
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
O Span input is bypassed (vented to the atmosphere through the
The H
2
O Span Bypass outlet) when it is not selected, so it permits continuous
H
2
flow. This allows a dewpoint generator to be connected directly to the
O Span inlet. The dewpoint generator’s internal pump can push air into the
H
2
valve module even when the H
O Span valve is not selected, minimizing
2
errors caused by pressurization inside the dewpoint generator. When the
O Span valve is selected, the dewpoint generator pushes moist air through
H
2
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 (allowing a shorter tube between the valve module
and the EC155), but setting 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 H
O span operation to prevent pressurizing the dewpoint
2
generator.
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 manual should be performed.
The CPEC310 valve module includes a heater and a fan to keep the valves
within their operating range of 0 to 60 °C. The valve heater turns on/off at
2 °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 min to warm up to the operating range of 0 to 60 °C.
21
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
4.11.4 CPEC300-Series Pump Module
The pump module for the CPEC300-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 weather-tight 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.
If the pump fails, a replacement pump is available (see Section 4.10,
Replacement Parts
Replacement
in the pump module is unlikely to clog over the lifetime of any CPEC300-series
system.
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 CPEC300-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’s speed as needed to
match pump_flow_raw to the setpoint flow pump_flow_set_pt.
Pump_flow_set_pt is a system configuration variable.
(p. 17)). See Appendix L, CPEC300 Series Pump
(p. L-1), for instructions on replacing the pump. The filter cartridge
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.
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 CPEC300-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
CPEC300-series system is started at 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.
22
4.12 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
CPEC300: 34 x 25 x 13 cm (13.4 x 9.8 x 5.1 in)
CPEC306/310: 54 x 44.5 x 29.7 cm (21.3 x 17.5 x 11.7 in)
Ingress protection
CPEC300 IP65
Weight basic system
CPEC300: 4.0 kg (8.9 lb)
CPEC306: 13.7 kg (30.3 lb)
CPEC310: 15.4 (33.9 lb)
CDM-A116 module: 0.9 kg (1.95 lb)
Pump module
Cable length: 3.0 m (10 ft)
Inlet connection: 3/8-in Swagelok
Pressure sensor range: 15 to 115 kPa
Pumping speed: 3 to 9 LPM (automatically controlled at the
Dimensions CPEC300: 35.6 x 29.2 x 13.5 cm (14.0 x 11.5 x 5.3 in)
Weight w/out mounting: 5.4 kg (11.8 lb)
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
2/
set-point, typically 7 LPM)
CPEC310 three-valve module
Inlets: Zero, CO
Outlets: Analyzer and H
Connections: 1/4-in Swagelok
span, and H2O span
2
O bypass
2
®
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)
EC155 and CSAT3A Specifications: see the user manual: EC155 CO
O Closed-path Gas Analyzer Manual and CSAT3 Three Dimensional Sonic
H
2
and
2
Anemometer Manual
View compliance documentation at www.campbellsci.com/cpec300.
2/
Not intended for marine environments
23
5. Installation
5.1 Mounting
5.1.1 Support Structure
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
The following tools are required to install a CPEC300-series system in the
field. Additional tools may be required for a user-supplied tripod or tower.
• 9/16-in, open-end wrench
• 1/2-in, open-end wrench
• 11/16-in, open-end wrench
• Adjustable wrench
• Small, flat-tip screwdriver (included with EC100 and CPEC300-series
system)
• Large, flat-tip screwdriver
• Sledgehammer (to drive grounding rod into the ground)
• 3/16-in hex-key wrench (included with CM250 leveling mount)
A CPEC300-series system has three major components that must be mounted
to a user-provided support structure.
EC sensors (EC155 and CSAT3A): Mounted on a horizontal round pipe of
3.33 cm (1.31 in) outer diameter, such as the CM20X crossarm as in FIGURE
5-1.
EC100 electronics (denoted as “CPEC300 Closed-Path Eddy-Covariance
System” for the CPEC300): Mounted within 3.0 m (10.0 ft) of the EC
sensors. The EC100 mounting bracket will accommodate a pipe at any
orientation, with outer diameter from 2.5 cm to 4.8 cm (1.0 in to 1.9 in).
For CPEC 300:
CPE300 pump module enclosure: Mounted within 3.0 m (10.0 ft) of the
CPEC300 enclosure. The pump module enclosure is similar to the ENC10/12,
with the same mounting options (tower, tripod, leg, or pole).
For CPEC306/310:
CPEC306 or CPEC310 enclosure: Mounted where it can be accessed easily
to retrieve data from the microSD cards in the datalogger. The CPEC306 or
310 enclosure is similar to the ENC16/18, with the same mounting options
(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 EC measurement height to minimize wind disturbance.
5.1.2 Mount Enclosures
Mount the EC100 electronics within 3.0 m (10.0 ft) of the EC 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
24
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
NOTE
humidity indicator card in the mesh pocket in the enclosure door. Reseal the
remaining two desiccant packs in the bag for later use.
The EC100 should be mounted vertically to prevent the ingress of
water from precipitation.
The mounting bracket will accommodate a horizontal, vertical, or angled pipe
from 2.5 cm to 4.8 cm (1.0 in to 1.9 in) diameter. See the EC155 user manual
for details on configuring the EC100 mounting bracket.
CPEC300:
Mount the CPEC300 enclosure and the CPEC300 pump module within 3.0 m
(10.0 ft) distance. The enclosure and pump module are shown mounted
vertically on the CM210 tripod in FIGURE 4-4, but they may also be mounted
on the leg of the tripod, triangular tower, or large-diameter pole, depending on
the site requirements and the mounting options ordered.
The CPEC300 enclosure is not intended for marine environments.
The ingress protection is not sufficient for the salinity of these
environments, and corrosion will occur to components within the
enclosure.
CPEC306:
The CPEC306 enclosure and the EC100 electronics are mounted as shown in
FIGURE 4-8, with the CPEC306 enclosure and EC100 enclosure mounted on
the legs of a tripod. They can also be mounted on a triangular tower, or largediameter 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 4-11, with the CPEC306 enclosure and EC100 enclosure mounted on
the legs of a tripod. They can also be mounted on a triangular tower or largediameter 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. For cylinders of CO2 and Zero air (needed if there is not a scrub
module) they 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.
5.1.3 Install EC Sensors
Install a horizontal mounting crossarm at the height desired for the EC
measurement. This crossarm must be within ±15 degrees of horizontal to level
the sonic anemometer. Point the crossarm into the predominant wind direction
to minimize wind disturbance caused by wind flowing past the mounting
structure and EC sensors. The outer diameter of the crossarm should be 3.3 cm
(1.3 in). The CM202 crossarm is shown in FIGURE 5-1.
25
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
CSAT3A Sonic
Anemometer Head
EC155 Gas Analyzer
CM20X Crossarm
CM250 Leveling
CPEC300
Mounting Platform
CM20X Crossarm
CM210 Crossarm-to-
Pole Bracket
FIGURE 5-1. 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 CPEC300-series
mounting platform. FIGURE 5-2 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 CO
and H2O Closed-path Gas Analyzer
2
manual.
Mount
FIGURE 5-2. Mounting of EC155 and CSAT3A
26
5.2 Plumbing
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURES 5-3 through 5-5 show an overview of the basic plumbing
configuration of a CPEC300, CPEC306, and CPEC310, respectively. FIGURE
5-3 shows how a CPEC300 enclosure is connected to the pump module and
EC155. The EC155 is connected to the CPEC300 pump module’s Inlet
connector and the pump module umbilical cord is connected to the connector
labeled Pump Module on the CPEC300 enclosure.
FIGURE 5-3. Plumbing connections for CPEC300
FIGURE 5-4 depicts the plumbing required for the CPEC306. The only
plumbing required is the connection of the EC155 to the inlet connector of the
pump on the bottom of the CPEC306 enclosure.
FIGURE 5-4. Plumbing connections for CPEC306
FIGURE 5-5 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
27
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
span the EC155, a 1/4-in OD tubing that has been swaged on both ends is used
to connect the EC155 to the valve module. A CO
cylinder and either a Zero
2
gas (ultra-pure nitrogen) cylinder or scrub module are connected to the valve
module for zero and spanning. More information on zero and span procedures
can be found in Section 7, Zero and Span
(p. 80).
FIGURE 5-5. Plumbing for CPEC310 with optional scrub module
5.2.1 Pump Module
For the CPEC300 connect the EC155 to the pump module as shown in
FIGURE 5-3. If the EC155 is within 15 m (50 ft) of the pump module, 3/8-in
OD tubing is recommended. For longer distances, up to 150 m (500 ft), a 1/2-in
OD tube minimizes pressure drop in the tube.
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. Campbell Scientific supplies pre-swaged pump tube
assemblies with reducers at each end for this purpose.
Connect one end of the pump tube to the last fitting of the vortex assembly
which is connected to the port labeled Pump on the back of the EC155
analyzer. Connect the other end to the fitting labeled Inlet on the CPEC300
pump module as shown in FIGURE 5-3.
5.2.2 Zero/Span with the 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 CO
appropriate regulators. If the user has chosen the optional CPEC310 scrub
module, then no cylinder of zero air is required.
span gas with
2
The rest of this section assumes the use of cylinders of compressed gas, but see
Appendix K, CPEC310 Scrub Module Installation, Operation, and
Maintenance
(p. K-1), for details on the scrub module.
28
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
NOTE
NOTE
NOTE
NOTE
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 CO
Fittings
span cylinder is selected. Refer to Appendix J, Using Swagelok
2
(p. J-1), for information on installing and replacing Swagelok fittings.
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.
Make sure there are no leaks 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.
When inlets are not in use, replace the Swagelok plugs to keep the
system clean.
Connect the valve module’s Analyzer outlet to the Zero/Span fitting on 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.
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 dewpoint generator. The bypass on
this inlet will avoid pressurizing the dewpoint generator.
Some systems, such as the AP200 CO2/H2O Atmospheric Profile
system, require a tee in the connection from the dewpoint
generator to bleed off excess flow and avoid pressurizing the
dewpoint generator. Do not use a tee to connect a dewpoint
generator to the CPEC310.
29
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 5-6. Connecting pump tube from EC155 analyzer to pump
module
The CPEC306 and CPEC310 do not have a separate pump module since the
pump resides in the main enclosure. Therefore, pump tubing is connected to the
main enclosure that is labeled Inlet.
5.3 Wiring
5.3.1 Ground Connections
Any CPEC300-series system enclosure and the EC100 electronics must be
earth grounded as illustrated in FIGURE 5-7. Ground the tripod and enclosures
by attaching heavy gage grounding wire (12 AWG minimum) 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 Product Manual.
FIGURE 5-7. Enclosure and tripod grounded to a copper-clad
grounding rod
30
5.3.2 EC Sensor Cables
TABLE 5-1. SDM Wiring
NOTE
EC155
Analyzer
CSAT3A Cable
EC155 Sample-cell Cable
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 5-8).
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Cable
FIGURE 5-8. EC155 and CSAT3A electrical connections; mounting
hardware and tubing not shown)
CPEC300-series instruments that are ordered with a CR6, are prewired with the appropriate EC100 wiring. For users that need to
wire the system, follow the next sections to wire the connection
between the EC100 and the CPEC300-series enclosure.
Wire the SDM communications cable (CABLE4CBL-L) between the EC100
and the CPEC300-series enclosure as shown in FIGURE 5-9 and FIGURE
5-10. TABLE 5-1 shows the color scheme of the SDM wires.
Description Wire Color EC100 CR6
SDM Data Green SDM-C1 SDM-C1
SDM Clock White SDM-C2 SDM-C2
SDM Enable Red/Brown SDM-C3 SDM-C3
Digital Ground Black Ground Ground
Shield Clear Ground Ground
31
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
NOTE
Power Wire to + 12 Vdc
Power Supply (off) goes here
Power Wire to EC100
SDM Wires to EC100
Ground Wire to + 12 Vdc
Power Supply (off)
Ground Wire to EC100
SDM Black and Clear
Ground Wires
To bring cables into the CPEC306 and CPEC310 enclosure,
remove the cap from the cable feedthrough by loosening the
thumbscrew and pulling the cap off.
The CPEC306 and CPEC310 wires connect to a DIN rail located
inside of the main enclosure. This DIN rail then connects to the
CR6 datalogger. To connect a wire to the DIN rail terminal blocks
of the CPEC306 and CPEC310 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 CPEC306 and CPEC310 enclosure is not powered, and wire the
power cable (CABLEPCBL-L) from the EC100 electronics to the enclosure as
shown in FIGURE 5-9 and FIGURE 5-10.
FIGURE 5-9. Wiring the EC100 to a CPEC306 and CPEC310
enclosure
Secure the SDM and power cables in the EC100 with a cable tie.
32
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
CAUTION
EC100 Power
Cable
EC100 SDM
Cable
FIGURE 5-10. Wiring to EC100 electronics
5.3.3 Pump Module Cable for a CPEC300
Ensure the CPEC300 system is not powered, and connect the pump module
cable to the bottom of the CPEC306 or CPEC310 system enclosure (or
CPEC300 pump module enclosure).
5.3.4 Apply Power
All CPEC300-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.
Before applying power, verify all of the tubes and cables have
been connected according to the instructions above.
To reduce the risk of shorting the power supply, especially
when using batteries, connect the power cable to the
CPEC300-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 CPEC306 and CPEC310
power terminals, as shown in FIGURE 5-10, to a user-supplied, 12 Vdc power
supply.
For the CPEC300, the power cables will be plugged into the orange splicing
switches attached to the top of the enclosure, as shown in FIGURE 5-11.
33
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
FIGURE 5-11. CPEC300 splicing switches
Replace the cap on the CPEC306 and CPEC310 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.
In very humid conditions or locations with insects and small
rodents it may be helpful to seal the cable feedthrough with
plumber’s putty.
6. Configure the EasyFlux DL Program
EasyFlux™ DL CR6CP is a CRBasic program that enables a CR6 datalogger to
collect fully corrected fluxes of CO
surface heat (optional), and momentum from any CPEC300-series system with
optional GPS and energy balance sensors. The program processes EC data
using commonly used corrections in the scientific literature. Because the
number of analog channels on the CR6 is limited, the program also supports
the addition of a CDM-A116 analog channel expansion module, which allows
a full suite of energy balance sensors, thus enabling the program to calculate
the ground surface heat flux and energy closure.
, latent heat (H2O), sensible heat, ground
2
Specifically, the program supports data collection and processing from the
following systems and sensors.
34
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
• CPEC300
o EC155 CO
O Gas Analyzer with EC100 Electronics
2/H2
o CAST3A sonic anemometer
o CR6 datalogger (housed in EC100)
o Pump Module
• CPEC306
In additional to components listed for CPEC300 above, the
CPEC306 includes a:
o CDM-A116 analog channel expansion module
o System Enclosure (houses CR6, pump module, CDMA-116
module)
• CPEC310
In addition to components used for CPEC300 and CPEC306
above, the CPEC310 includes a:
o valve module for automated zero and span of the gas
analyzer
o SDM-CD16S Solid-State DC Controller
o optional scrub module for providing zero gas (i.e., gas
without CO
or H2O for zeroing the analyzer)
2
GPS Receiver (optional, qty 0 to 1)
• GPS16X-HVS
Fine-wire thermocouple (optional, qty 0 to 1)
• FW05
• FW1
• FW3
Biometeorology (biomet) and energy balance sensors (optional)
• Temperature/Relativity Humidity (RH) Probe (qty 0 to 1)
o HMP155A
o EE181
• Radiation measurements
o Option 1
− NR-LITE2 Net Radiometer (qty 0 to 1)
− CS300, LI200X, or LI200RX Pyranometer (qty 0 to
1)
− LI190R Quantum Sensor (qty 0 to 1)
− SI-111 Infrared Radiometer (qty 0 to 1)
o Option 2
− NR01 or CNR4 4-Way Radiometers (qty 0 to 1)
• TE525MM Rain Gage (qty 0 to 1)
• TCAV Soil Thermocouple Probe (qty 0 to 2)
• Soil Water Content Reflectometer (qty 0 to 2)
o CS650
o CS655
• Soil Heat Flux Plates (qty 0 to 4)
o Option 1: HFP01 plates (qty 0 to 4)
o Option 2: HFP01SC self-calibrating plates (qty 0 to 4)
It may be possible to customize the program for other sensors or
quantities in configurations not described here. Contact Campbell
Scientific for more information.
35
6.1 Operation
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
If the CPEC300-series system was ordered with the CR6 factory installed, the
system is shipped with the EasyFlux DL CR6CP program installed. For users
that will install a previously purchased CR6 into a CPEC300-series system or
for wiring of the optional sensors mentioned above, refer to Appendix C,
Wiring the CR6 and Optional Energy Balance Sensors
(p. C-1).
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, but also periodically as site
conditions change (e.g., canopy height is a variable that may need to be
adjusted throughout a growing season). Section 6.2, Set Constants
details on editing constants, and Section 6.3, Edit Input Variables
(p. 36), gives
(p. 43), gives
details on editing variables.
Typical operation also includes periodic zeroing and spanning of the EC155
gas analyzer. Section 7, Zero and Span
(p. 80), provides more details on zeroing
and spanning, either manually for the CPEC300 and CPEC306, or
automatically with the CPEC310.
6.2 Set Constants
6.2.1 Categories of Constants
To begin program operation, the values for constants should be set or verified.
TABLE 6-1 lists all of the constants with descriptions. Generally, the constants
fall into four categories:
Program Function Constants
These are constants that determine the timing of code execution, frequency of
writing to output tables, memory allocation, etc. In most cases, the default
constants for these values can be maintained.
Sensor Selection Constants
All sensor selection constants begin with the prefix SENSOR. The value is set
to -1 as 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 -1 as TRUE. When set to TRUE, the wiring in TABLE C-11
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 0 as FALSE.
Sensor Quantity Constants
The value for these constants indicates the number of each type of sensor in the
system. For example, if four soil heat flux (SHF) plates were being used, the
constant NMBR_HFP would be set to 4.
Sensor Calibration Constants
Some sensors have unique parameters for their measurement working
equations (e.g., multipliers and/or offsets for linear working equations) that are
used to convert their raw measurements into the values applicable in analysis.
Typically, these parameter values are found on the calibration sheet from the
sensor’s original manufacturer. For example, if an NR-LITE2 net radiometer is
36
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
NOTE
being used, a unique multiplier is set in the following line of code: Constant
NRLIT_SNSTVT = 16. The value entered is the sensor sensitivity provided in
the NR-LITE2 calibration sheet.
Constants relating to a particular sensor have been grouped
together and have the sensor selection constant at the beginning,
such that if the sensor selection constant is set to FALSE, the other
constants for that sensor may be ignored. For example, all of the
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 and the next four constants dealing with multipliers and
offsets will be ignored in the program.
6.2.2 Accessing the Constants
The constants may be accessed for editing in three ways: via the Const Table
menu on the CR1000KD keypad, via the Const_Table under the Connect
Screen of LoggerNet while connected to the datalogger, or by opening the
program code in CRBasic Editor. Details on each of these methods are
provided in sections below.
CR6 dataloggers shipped with CPEC300-series systems are
among the newer CR6 units that have a larger CPU memory size
(30 MB), which enables constants on this program to be set and
the program recompiled using the datalogger keypad, LoggerNet,
or CRBasic Editor. However, if an older CR6 with smaller CPU
memory (i.e., 1 MB) is transferred into a CPEC300-series system,
then the constants may only be set using the CRBasic Editor, as
described in the section Using CRBasic Editor below. CPU
memory size of a logger may be verified by connecting to it with
the LoggerNet Connect Screen and then using File Control to view
the CPU memory size.
Using the Datalogger Keypad
If the system is already setup at the site with the datalogger powered and
running the program, then using the CR1000KD keypad is the most
conventient way to edit the constants. Start by connecting a CR1000KD
Keyboard Display to the CR6 CS-I/O port. Once connected, press Enter twice
until the main menu is shown. Press the down arrow until the menu titled
Const Table is highlighted and press Enter. Use the up and down arrow
buttons to navigate to different constants. To change the value of a constant,
make sure the desired constant is highlighted and press Enter. Then enter the
new value and hit Enter again. Upon completion of editing constants, be sure
to navigate to the last row of the Const Table titled Apply and Restart, press
Enter, and press Enter once more to confirm that you would like to save the
changes. The program is then recompiled and the new values for constants are
loaded. The user may now move on to review site-specific variables; see
Section 6.3, Edit Input Variables
(p. 43), for next steps.
To see a schematic showing the layout of all the CR1000KD custom menus,
see FIGURE 6-2. Recall also that a complete list of the user-editable constants
with descriptions is found in TABLE 6-1.
37
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
Press Esc on the CR1000KD keypad at any time to return to the
previous menu or screen.
Using LoggerNet
The constants may be edited using LoggerNet software on a PC. Use the
LoggerNet Connect Screen to connect to the datalogger, and then use the Table
Monitor to view the table called Const_Table. To edit a value, click on the cell
to the right of the constant name, enter the new value, and press Enter. Once
all new values are entered, scroll to the bottom of the Const_Table and change
the value of ApplyAndRestart from FALSE to TRUE and press Enter. The
software may lose connection with the datalogger while the program is
recompiled. Connect again and view the table again to verify the new values
were saved. Once this is done, the user is ready to set site-specific variables;
see Section 6.3, Edit Input Variables
(p. 43).
Using CRBasic Editor
The constants may be edited by opening the program 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” (see FIGURE 6-1); a user may also search for the word
“unique” to find lines of code with user-editable constants.
Once changes are completed, the program must 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,
PC400, or PC200W user-interface software. After sending the program, its
site-specific variables are ready to be reviewed and edited; see Section 6.3, Edit
Input Variables
(p. 43).
38
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 6-1. Example screen from CRBasic Editor showing user-
defined configuration constants
39
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-1. Program Constants
Constant Name
Default Value
Description
Indented constant names indicate they are only applicable if the prior non-indented constant is true/applicable.
SCN_INTV 100
SLW_SCN_INTV 5000 Slow sequence measurement rate in milliseconds
OUTPUT_INTV 30 Interval in minutes over which to compute statistics and fluxes
DAY_FLUX_CRD 30
DAY_TSRS_CRD 1
NTCH_FRQ_SLW 60
ONE_FL_TABLE – 1
DVC_CDM_A116 – 1
CDM_SN 0000 The serial number of the CDM-A116
CPI_ADDR_CDM 1 The CPI address of the CDM-A116
CPI_DEVICE “CDMA116”
SDM_CLCK_SPD 30
EC100SDM_ADR 1 The SDM address of the EC100.
BANDWIDTH 5
Measurement rate in milliseconds. Valid options: 50 (20 Hz), 100
(10 Hz), 200 (5 Hz), or 1000 (1 Hz)
Number of days of data to write to each flux data output file stored
on the card before beginning a new file
The number of days of data to write to each time series output files
stored on the card before beginning a new file.
Analog integration parameter for measurements in the slow
sequence. Options: 60 (filters 60 Hz noise), 50 (filters 50 Hz
noise). Choose the option that matches the AC power Hz at site.
Set to – 1 (TRUE) to combine the Flux_CSIFormat and anciliary
Flux_Notes tables into one full or large table. Set to 0 (FALSE) to
keep the two tables separate.
Set to – 1 (TRUE) for the CPEC306 or CPEC310 if they include a
CDM-A116 device. Set to 0 (FALSE) for the CPEC300.
A custom name the user can give the CDM-A116. It must be in
quotation marks.
SDM clock bit period in µs. If long cables are used that result in
skipped scans, this value should be increased. In most cases, the
default is adequate.
The bandwidth for measurements from the EC100. For spectral
analysis, set to one half the sampling frequency; otherwise, leave
at default. Options: 5, 10, 12.5, or 20 Hz.
CEL_PRSS_TYP
CPEC310 – 1
ZRO_SPN_INTV 1 Number of days between each automatic zero and span.
ZRO_SPN_OFST 0
TIME_ZRO_SPN 60
CHECK_ZRO – 1
1
Set to 1 to indicate an absolute pressure sensor in the sample cell.
Set to -1 (TRUE) for CPEC310 to indicate the system has a valve
module for automatic zero and span. Set to 0 (FALSE) for
CPEC300 or CPEC306.
Number of minutes to offset the automatic zero/span. For example,
if ZRO_SPN_INTV is 1, and ZRO_SPN_OFST is 60, then the
auto zero/span will occur at 1:00AM each day.
Number of seconds on each site or stage of the automatic zero and
span. 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.
Set to – 1 (TRUE) to measure and record the gas readings while
zero gas is flowing but before the analyzer is zeroed. Set to 0
(FALSE) to not measure and record.
40
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-1. Program Constants
Constant Name
Default Value
Description
Set to – 1 (TRUE) to set the analyzer H2O readings to the span gas
Indented constant names indicate they are only applicable if the prior non-indented constant is true/applicable.
SET_ZRO – 1
Set to – 1 (TRUE) to set the analyzer readings to zero while zero
gas is flowing. Set to 0 (FALSE) to not set the readings to zero.
Set to – 11 (TRUE) to measure and record the gas readings while
CHECK_CO2SPN – 1
CO2 span gas is flowing but before setting the span. Set to 0
(FALSE) to not measure and record.
SET_CO2SPN – 1
Set to – 1 (TRUE) to set the analyzer CO
concentration while CO
not set the readings to the CO
span gas is flowing. Set to 0 (FALSE) to
2
span concentration.
2
readings to the span gas
2
Set to – 1 (TRUE) to measure and record the gas readings while
H
O span gas is flowing but before setting the span. Set to 0
2
CHECK_H2OSPN 0
(FALSE) to not measure and record.
Note: this is typically set to 0 since having an autonomous field
O span gas source is difficult.
H
2
concentration while H2O span gas is flowing. Set to 0 (FALSE) to
SET_H2OSPN 0
not set the readings to the H
O span concentration.
2
Note: this is typically set to 0 since having an autonomous field
O span gas source is difficult.
H
2
CPEC310SCRUB 0
SENSOR_GPS 0
Set to – 1 (TRUE) if the system has a scrub module, else set to 0
(FALSE).
Set to – 1 (TRUE) if using a GPS16X sensor, if not, set to 0
(FALSE)
UTC_OFST – 7 Difference between local time and UTC/GMT time in hours.
SENSOR_FW 0
SENSOR_T_RH 0
TMPR_MULT 0.14
TMPR_OFST -80
RH_MULT 0.1
Set to – 1 (TRUE) if using a fine wire thermocouple, if not, set to 0
(FALSE).
Set to – 1 (TRUE) if using a Temp/RH probe, if not, set to 0
(FALSE)
The multiplier for the raw temperature reading. Set to 0.14 for
HMP155A or 0.1 for EE181. Set to 0.1 for HMP45C and HC2S3.
The offset for the temperature reading. Set to – 80 for HMP155A
or – 40 for EE181. Set to -40 for HMP45C and HC2S3.
Multiplier for raw RH reading. Set to 0.1 for HMP155A or
EE181.Set to 0.1 for HMP45C and HC2S3.
RH_OFST 0.0 Offset for RH reading. Set to 0 for HMP155A or EE181.
SENSOR_NRLIT 0
Set to – 1 (TRUE) if using an NR-LITE2, if not, set to 0 (FALSE).
If true, SENSOR_NR01 and SENSOR_CNR4 must be set to false.
If using an NR-LITE2, enter the unique sensitivity as reported on
RNLIT_SNSTVT 16.0
the sensor’s calibration sheet.
Units: µV∙W
-1∙m-2
Set to – 1 (TRUE) if using a CS300, if not, set to 0 (FALSE). If
SENSOR_CS300 0
true, SENSOR_NR01, SENSOR_CNR4, and LI200X must be set
to false.
41
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-1. Program Constants
Constant Name
Default Value
Description
Indented constant names indicate they are only applicable if the prior non-indented constant is true/applicable.
Set to – 1 (TRUE) if using a LI200X or LI200RX, else set to 0
SENSOR_LI200 0
PYRAN_MULT 5
PYRAN_OFST 0
SENSOR_LI190 0
LI190_SNSTVT 6.45
LI190_OFST 0
SENSOR_SI111 0
m0_SI111 0
m1_SI111 0 Unique sensor calibration parameter.
m2_SI111 0 Unique sensor calibration parameter.
b0_SI111 0 Unique sensor calibration parameter.
b1_SI111 0 Unique sensor calibration parameter.
b2_SI111 0 Unique sensor calibration parameter.
SENSOR_NR01 0
SENSOR_CNR4 0
SW_IN_SNSTVT 15.0
SW_OUT_SNSTVT 15.0
LW_IN_SNSTVT 8.0
LW_OUT_SNSTVT 8.0
SENSOR_TE525 0
(FALSE). If true, SENSOR_NR01, SENSOR_CNR4, an
SENSOR_CS300 must be set to false.
Multiplier for the pyranometer reading. Set to 5 for CS300 or 200
for LI200X or LI200RX.
Units: W∙m-2∙mV-1
Offset for the pyranometer reading. Set to 0 for CS300, LI200X, or
LI200RX.
Units: W∙m-2
Set to – 1 (TRUE) if using a LI190 or LI190R, if not, set to 0
(FALSE). If true, SENSOR_NR01 and SENSOR_CNR4 must be
set to false.
If using a LI190 or LI190R, enter the unique sensitivity as reported
on the sensor’s calibration sheet.
Units: µA∙m-2∙s mmol-1
Offset for LI190R.
Units: µmol∙m-2∙s-1
Set to – 1 (TRUE) if using the SI111, if not, set to 0 (FALSE). If
true, SENSOR_NR01 and SENSOR_CNR4 must be set to false.
Enter the unique calibration parameter called “m0” found on the
sensor calibration sheet.
Set to – 1 (TRUE) if using a NR01, if not, set to 0 (FALSE). If
true, SENSOR_NRLIT, _CNR4, _CS300, _LI200X, _LI190R_SB,
and _SI111 must be set to false.
Set to – 1 (TRUE) if using a CNR4, else set to 0 (FALSE). If true,
SENSOR_NRLIT, _NR01, _CS300, _LI200X, _LI190R_SB, and
_SI111 must be set to false.
If using a NR01 or CNR4, enter the unique sensitivity of the
upward facing pyranometer as reported on the sensor calibration
sheet.
Units: µV∙m2∙W-1
Unique sensitivity of the downward facing pyranometer.
Units: µV∙m2∙W-1
Unique sensitivity of the upward facing pyrgeometer.
Units: µV∙m2∙W-1
Unique sensitivity of the downward facing pyrgeometer.
Units: µV∙m2∙W-1
Set to – 1 (TRUE) if using a TE525-series rain gauge, if not set to
0 (FASLE).
42
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-1. Program Constants
Constant Name
Default Value
Description
Set to – 1 (TRUE) if a CS650 or CS655 is used, if not, set to 0
Set to – 1 (TRUE) if using a HFP01, if not, set to 0 (FALSE). If
Number of HFP01 or HFP01SC sensors used.
Indented constant names indicate they are only applicable if the prior non-indented constant is true/applicable.
If using a TE525-series rain gauge, enter the multiplier. Units: mm
TE525_MULT 0.1
SENSOR_TCAV 0 Set to – 1 (TRUE) if using a TCAV, if not, set to 0 (FALSE).
NMBR_TCAV 0
per tip. Multiplier for TE525MM = 0.1 mm/tip as default, TE525 =
0.254 mm/tip, TE525WS = 0.254 mm/tip, TE525/WS w/ 8 in
funnel 0.1459 mm/tip.
Number of TCAV probes used.
Max: 2
SENSOR_CS65X 0
NMBR_CS65X 0
CSSDI12_ADR1 1 SDI12 address of the first CS65X probe.
CSSDI12_ADR2 2 SDI12 address of the second CS65X probe.
SENSOR_HFP01 0
SENSOR_HFPSC 0
NMBR_HFP 0
HFP_SNSTVT_1 62.0
HFP_SNSTVT_2 62.0
HFP_SNSTVT_3 62.0
HFP_SNSTVT_4 62.0
CAL_INTV 1440
(FALSE).
Number of CS650 or CS655 probes used.
Max: 2
true, SENSOR_HFPSC must be set to false.
Set to -1 (TRUE) if using a HFP01SC, if not, set to 0 (FALSE). If
true, SENSOR_HFP01 must be set to false.
Max: 4
If using heat flux plates, enter the unique sensitivity of the first
plate as reported on the sensor calibration sheet.
Units: µV∙m2∙W-1
Unique sensitivity of second heat flux plate.
Units: µV∙m2∙W-1
Unique sensitivity of third heat flux plate.
Units: µV∙m2∙W-1
Unique sensitivity of fourth heat flux plate.
Units: µV∙m2∙W-1
If using a HFP01SC, this is the time interval in minutes between
auto calibrations.
6.3 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 datalogger and after
the program is loaded and running, press Enter twice to access the main
menu. FIGURE 6-2 shows an organizational schematic for all the keypad
menus. Under the main menu, use the keypad’s down arrow to scroll down to
each of the submenus. To select a submenu, make sure the desired submenu is
highlighted 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 TABLES 6-2, 6-3, and 6-4, respectively.
43
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
If a CR1000KD is not available, an alternative option is to review and edit
variables using LoggerNet. Under the Connect Screen’s Table Monitor, select
the Public Table and then scroll to the appropriate variables. The last column
in TABLES 6-2, 6-3, and 6-4 shows 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.
FIGURE 6-2
is a schematic of the entire menu structure. When
beginning operation of a system, the user must review and set
constants in the Const Table (see Section
6.2, Set Constants (p. 36))
and variables in the following menus: Initial Configuration, 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 Section 7, Zero and
(p. 80).
Span
44
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
45
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
46
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
FIGURE 6-2. 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 CPEC300 or CPEC306. In
the constants table, indented constants are only applicable if the
preceding non-indented constant is applicable.
47
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-2. Variables from Initial Configuration Menu
CORRCTN_OFF
The dew point temperature of
Only applicable to a CPEC310
set point for flow of zero or
Station Variable Default Description
Used to select the barometer to
use for measurements of
Pick
Source
EB
ambient pressure. Set to EB for
EC100 enhanced barometer,
BB for the EC100 on-board
basic barometer, or UB for a
Change Press
Source
user-supplied barometer.
If the variable Pick Source has
been changed, this variable
Reset
Sourc
FALSE
must be set to TRUE to enable
the change. The program will
return Reset Sourc to FALSE
once the change has been
applied.
Used to enable the Kaimal
sonic transducer wind
Pick
Crrctn
CORRTN_OFF
shadowing correction as
described in the CSAT3B
manual. CORRCTN_ON
enables the correction, while
Shadow
Correction
If the variable Pick Crrctn has
been changed, this variable
must be set to TRUE to enable
Set Crrctn FALSE
the change. The program will
return Set Crrctn to FALSE
once the change has been
applied.
The dry molar mixing ratio
CO2 Spn Gas 400 ppm
concentration of the CO
gas. A concentration close to
ambient is recommended.
disables it.
span
2
Name of variable in
Public Table (when no
CR1000KD available)
press_source
0 = BB
1 = UB
2 = EB
set_press_source_flg
–1 = True
0 = False
shadow_corr
–1 = CORRCTN_ON
0 = CORRCTN_OFF
set_shadow_corr_flg
–1 = True
0 = False
CO2_span_gas
H2O Span TDP 10 deg C
Sample Flw 8 L min-1
Zro/Spn Flw 1 L min-1
the H2O span gas (i.e., the
dewpoint temperature setting of
the dewpoint generator).
The 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 user
manual for more details.
with valve module. This is the
Td_span_gas
pump_flow_set_pt
valve_flow_set_pt
48
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-2. Variables from Initial Configuration Menu
span gas through the gas
A read-only variable reporting
A read-only variable reporting
A read-only variable reporting
Used to restore gas analyzer
Used to restore gas analyzer
Used to restore gas analyzer
Used to restore gas analyzer
desired value and then set Reset
Station Variable Default Description
analyzer. If the system is not a
CPEC310, this variable is
omitted.
Name of variable in
Public Table (when no
CR1000KD available)
Zero Span
Coeffs:
Current
Coeffs
Zero Span
Coeffs:
Reset/Change
Coeffs
CO2 Zro
Coef
CO2 Spn
Coef
H2O Zro
Coef
H2O Spn
Coef
CO2 Zro
Coef
CO2 Spn
Coef
-
the current value of the CO2
ec100_setting_array(5,2)
zero coefficient.
-
the current value of the CO2
ec100_setting_array(6,2)
span coefficient.
A read-only variable reporting
-
the current value of the H
O
2
ec100_setting_array(7,2)
zero coefficient.
-
the current value of the H2O
ec100_setting_array(8,2)
span coefficient.
coefficients to 1 or a previously
user-recorded value. Enter the
desired value and then set Reset
1
Coefs variable to TRUE in
dflt_CO2_zero_coeff
order to apply. The program
will return Reset Coefs to
FALSE once the change has
been applied.
coefficients to 1 or a previously
user-recorded value. Enter the
desired value and then set Reset
1
Coefs variable to TRUE in
dflt_CO2_span_coeff
order to apply. The program
will return Reset Coefs to
FALSE once the change has
been applied.
H2O Zro
Coef
H2O Spn
Coef
coefficients to 1 or a previously
user-recorded value. Enter the
desired value and then set Reset
1
Coefs variable to TRUE in
dflt_H2O_zero_coeff
order to apply. The program
will return Reset Coefs to
FALSE once the change has
been applied.
1
coefficients to 1 or a previously
user-recorded value. Enter the
dflt_H2O_span_coeff
49
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-2. Variables from Initial Configuration Menu
Coefs variable to TRUE in
TABLE 6-3. Variables and Settings in Site Var Settings Menu
Station Variable
Units
Default
Description
Name of variable in
available)
7 = ICE
Displacement height. Set to zero (0)
Station Variable Default Description
order to apply. The program
will return Reset Coefs to
FALSE once the change has
been applied.
Used to apply and send new
Reset
Coefs
FALSE
coefficient variables to the gas
analyzer. Once sent, the
variable will return to FALSE.
Name of variable in
Public Table (when no
CR1000KD available)
reset_coeff_flg
Public Table (when
no CR1000KD
Meas Height m 2
Pck Surf typ – GRASS
Canopy hght
d m 0 (Auto)
z0
GPS height m 1
Bulk density kg·m-3 1300
C dry soil J·kg-1 K-1 870
HFP depth m 0.08
m
m 0 (Auto)
0.5
The height of the center of the eddycovariance sensor measurement
volumes above ground.
Type of surface at the measurement
site. Options are CROP, GRASS,
FOREST, SHRUB, BARELAND,
and WATER. This is used to
estimate displacement height,
The average height of the canopy.
for program to auto-calculate.
Roughness length. Set to zero (0)
for program to auto-calculate.
The height of the GPS reciever
above the ground surface. If GPS is
not used, this variable is omitted.
Average bulk density of soil. If
energy balance sensors are not used,
this variable is omitted.
Specific heat of dry mineral soil. If
energy balance sensors are not used,
this variable is omitted.
Depth of the soil heat flux plates. If
energy balance sensors are not used,
this variable is omitted.
height_measurement
surface_type
1 = CROP
2 = GRASS
3 = FOREST
4 = SHRUBLAND
5 = BARELAND
6 = WATER
height_canopy
displacement_user
roughness_user
height_GPS16X
soil_bulk_density
cds
thick_abv_HFP
50
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-3. Variables and Settings in Site Var Settings Menu
Distance along the sonic y-axis
Distance along the sonic x-axis
Distance along the sonic y-axis
–1 = South
Station Variable Units Default Description
Distance along the sonic x-axis
IRGA Coord x m 0.15020
between the sonic sampling volume
and the EC155 gas analyzer intake.
Name of variable in
Public Table (when
no CR1000KD
available)
separation_x_IRGA
IRGA Coord y m -0.03218
FW Coord x m 0.02627
FW Coord y m -0.02306
FW Diam m FW05_DIA
Sonic Azmth
Latitude
decimal
degrees
decimal
degrees
0
41.766
Pck Hemsph_Eq – NORTH
Longitude
decimal
degrees
111.855
Pck Hemsph_M – WEST
between the sonic sampling volume
and the EC155 gas analyzer intake.
between the sonic sampling volume
and fine-wire thermocouple. If no
fine-wire thermocouple is being
used, this variable is omitted.
between the sonic sampling volume
and the fine-wire thermocouple. If
no fine-wire thermocouple is being
used, this variable is omitted.
The diameter of the fine-wire
thermocouple. A numberical value
may be entered, or for convenience,
the following pre-defined constants
may be selected: FW05_DIA,
FW1_DIA and FW3_DIA. Each
constant corresponds to the diameter
of the FW05, FW1, or FW3
thermocouple, and their diameters
-5
are 1.27 x 10
-5
m, respectively. If no fine-
x 10
, 2.54 x 10-5, and 7.62
wire thermocouple is being used,
this variable is omitted.
The compass direction in which the
sonic negative x-axis points (i.e., the
compass direction in which the
sonic head is pointing).
The site latitude in degrees North or
South.
The site’s hemisphere, either north
or south of the equator. Options are
NORTH or SOUTH.
The site longitude in degrees East or
West.
The site’s longitudinal hemisphere,
either east or west of the prime
meridian. Options are EAST or
WEST.
separation_y_IRGA
separation_x_FW
separation_y_FW
FW_diameter
Predefined constants:
FW05_DIA
FW1_DIA
FW3_DIA
sonic_azimuth
Latitude
hemisphere_NS
1 = North
Longitude
hemisphere_EW
1 = East
–1 = West
51
TABLE 6-3. Variables and Settings in Site Var Settings Menu
Station Variable Units Default Description
Planar-fit alpha angle used to rotate
Planar-fit alpha angle used to rotate
Altitude m 1356
≤ 60
or
≥ 300
> 60
&
≤ 170
Planar
Fit Alpha
> 170
&
< 190
≥ 190
&
< 300
≤ 60
or
≥ 300
Planar
Fit Beta
> 60
&
≤ 170
> 170
&
< 190
decimal
degrees
decimal
degrees
decimal
degrees
decimal
degrees
decimal
degrees
decimal
degrees
decimal
degrees
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Name of variable in
Public Table (when
no CR1000KD
available)
The site altitude or elevation above
sea level.
altitude
Planar-fit alpha angle used to rotate
the wind when the mean horizontal
0
wind is blowing from the sector of 0
to 60 and 300 to 360 degrees in the
alpha_PF_60_300
sonic coordinate system (wind
1/
blowing into sonic head).
the wind when the mean horizontal
wind is blowing from the sector of
0
60 to 170 degrees in the sonic
alpha_PF_60_170
coordinate system (wind blowing
from the sector left and behind sonic
1/
head).
the wind when the mean horizontal
0
wind is blowing from the sector of
170 to 190 degrees in the sonic
alpha_PF_170_190
coordinate system (wind blowing
1/
from behind sonic head).
Planar-fit alpha angle used to rotate
the wind when the mean horizontal
wind is blowing from the sector of
0
190 to 300 degrees in the sonic
alpha_PF_190_300
coordinate system (wind blowing
from the sector right and behind
1/
sonic head).
Planar-fit beta angle used to rotate
the wind when the mean horizontal
0
wind is blowing from the sector of 0
to 60 and 300 to 360 degrees in the
beta_PF_60_300
sonic coordinate system (wind
1/
blowing into sonic head).
Planar-fit beta angle used to rotate
the wind when the mean horizontal
0
wind is blowing from the sector of
60 to 170 degrees in the sonic
beta_PF_60_170
coordinate system (wind blowing
1/
from left and behind sonic head).
Planar-fit beta angle used to rotate
the wind when the mean horizontal
0
wind is blowing from the sector of
170 to 190 degrees in the sonic
beta_PF_170_190
coordinate system (wind blowing
1/
from behind sonic head).
52
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-3. Variables and Settings in Site Var Settings Menu
Name of variable in
Public Table (when
no CR1000KD
Station Variable Units Default Description
available)
Planar-fit beta angle used to rotate
≥ 190
&
< 300
decimal
degrees
0
the wind when the mean horizontal
wind is blowing from the sector of
190 to 300 degrees in the sonic
coordinate system (wind blowing
from right and behind sonic head).
beta_PF_190_300
1/
The upwind distance of interest
from the station when the mean
horizontal wind is blowing from the
sector of 0 to 60 and 300 to 360
degrees in the sonic coordinate
system (wind blowing into sonic
≤ 60
or
≥ 300
m 100z
head).
Note: The program will report the
percentage of cumulative footprint
dist_intrst_60_300
from within this distance. The
default value is 100 times the
aerodynamic height, z. Recall that z
is the difference between the
measurement height and
displacement height.
The upwind distance of interest
Footprint
Dis Intrst
> 60
&
≤ 170
m 100z
from the station when the mean
horizontal wind is blowing from the
sector of 60 to 170 degrees in the
sonic coordinate system (wind
dist_intrst_60_170
blowing from left and behind sonic
head).
The upwind distance of interest
> 170
&
< 190
m 100z
from the station when the mean
horizontal wind is blowing from the
sector of 170 to 190 degrees in the
sonic coordinate system (wind
dist_instrst_170_190
blowing from behind sonic head).
The upwind distance of interest
from the station when the mean
≥ 190
&
< 300
m 100z
horizontal wind is blowing from the
sector of 190 to 300 degrees in the
sonic coordinate system (wind
dist_intrst_190_300
blowing from right and behind sonic
head).
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.
53
TABLE 6-4. Variables from the Run Station Menu
Variable Name
Default
Description
CR1000KD available)
Pump Tmpr Ok -
Set to TRUE to initiate an automatic zero
Pump Tmpr -
Pump flow 8.0 L·min-1
System Diag -
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
This is a display (read-only) variable
indicating whether the pump temperature
is within its operating range.
This is a display (read-only) variable
showing the temperature of the pump in
deg C.
This is a display (read-only) variable
showing the volumentric air flow to the
pump. If using vortex intake, this
includes both flow through sample cell
and through vortex bypass.
System diagnostic word. If set to 0, there
are no error conditions detected. For more
details on system diagnostic word, see
Appendix C.
Name of variable in Public
Table (in case no
pump_tmpr_ok
pump_tmpr
pump_flow
system_diag
Auto Z/S on FALSE
Pump Off FALSE
EC155_PW_on -
EC155 Messg -
EC155 Off FALSE
and CO2 span of the gas analyzer. The
system will return Auto Z/S on to
FALSE once the zero/span is initiated,
and the system will return to EC field
measurements upon completion of the
zero/span. This variable is ommitted if
the system is a CPEC300 or CPEC306
(i.e., no valve module).
For CPEC300 and CPEC306 systems,
select TRUE to disable the pump. Set to
FALSE to enable the pump. For
CPEC310 systems, the options are
PMP_OFF to disable the pump,
FLD_MEA to re-enable pump and
resume normal EC measurements, or
AUTO_ZS to initiate an automatic
zero/span cycle.
This is a read-only variable indicating
whether the EC155 is powered on.
This is a read-only string describing the
current status of the EC155.
Set to TRUE to power down the EC155.
Set to FALSE to power on EC155.
prfm_auto_zero_span_flg
sample_pump_off_flg
EC155_actual_pwr_on
message
ec155_pwr_off_flg
6.4 Data Retrieval
The program stores a very limited amount of data to the internal CPU of the
datalogger, so a microSD Flash card should be used with the CR6. TABLE 6-5
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. In cases where
54
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-5. microSD Flash Card Fill Times
NOTE
CAUTION
NOTE
real-time remote monitoring is desired, various telemetry options (for example,
cellular, radio, etc.) 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.
microSD Flash card size
Fill time with gas analyzer and
sonic only
Fill time with gas analyzer, sonic, FW,
and biomet/energy balance sensors)1/
2 GB ~32 days ~29 days
8 GB ~129 days ~121 days
16 GB ~258 days ~232 days
1/
Biomet and energy balance sensors used for this fill time estimate include the following: HMP155A, NR-LITE2, CS300,
LI200, LI190, SI-111, TE525MM, TCAV (qty 2), CS655 (qty 2), and HFP01 (qty 4)
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 6-5 are approximations for new cards.
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
testing. Use of consumer grade cards substantially increases the
risk of data loss.
6.5 Output Tables
Besides the Const_Table (see Section 6.2, Set Constants (p. 36)) and the
standard Public, Status, CPI Status, and DataTableInfo tables that the
datalogger reports, the program has eight output tables. TABLE 6-6 gives the
names of these output tables, along with a short description, the frequency at
which a record is written to the table, and the amount of memory allocated
from the CPU and SD card for each table.
The variable naming conventions used by AmeriFlux and other
flux networks have been adopted. Additionally, an output table
called Flux_AmeriFluxFormat reports the 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, this is possible by changing the
55
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-6. Data Output Tables
Time series data
Reports most
constant ONE_FULL_TABLE from FALSE to TRUE (see Section 6.2, Set
Constants
(p. 36), for details on changing constants).
Table Name Description Recording Interval
Time_Series
(aligned to
account for
electronic
SCAN_INTERVAL
(default 100 ms)
delays)
recent diagnostic
Diagnostic
flags from gas
analyzer and
SCAN_INTERVAL
(default 100 ms)
sonic
anemometer
EC100_Config_Notes
Reports settings
for the gas
analyzer and
sonic
anemometer
Whenever settings
are changed or
system is power
cycled
Processed flux
and statistical
Flux_AmeriFluxFormat
data following
reporting
conventions and
OUTPUT_INTERVAL
(default 30 minutes)
order of
AmeriFlux
Flux_CSFormat
Processed flux
and statistical
data
OUTPUT_INTERVAL
(default 30 minutes)
Intermediate
variables, station
Flux_Notes
constants, and
correction
variables used to
OUTPUT_INTERVAL
(default 30 minutes)
generate flux
results
Summary of
When an automatic
zero or span is
performed
ZeroSpan_Check_Notes
field calibration
data at the time
of an automatic
zero or span
System _Operatn_Notes
Records any
change in system
status
When there is a
change in system
status
Memory on
CR6 CPU
Auto-Allocate
(typically less than
1 hour)
1 record (most
recent scan)
128 records
Memory on
SD Card
Time_Series is
broken up into 1
day files (see
TABLE
0 records
10*DAY_FLUX_CRD
records
(default 300
records)
Broken up into
NMBR_DAY_CPU
(default 7 days)
30-day files; see
TABLE
calculate number
of files
Broken up into
NMBR_DAY_CPU
(default 7 days)
30-day files; see
TABLE
calculate number
of files
Broken up into
NMBR_DAY_CPU
(default 7 days)
30-day files; see
TABLE
calculate number
of files
ONLINCAL_SZE_CPU
(default 7 days)
500 records 10*DAY_FLUX_CRD
DAY_FLUX_CRD
(default 30 days)
6-5)
6-5 to
6-5 to
6-5 to
56
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-7. Data Fields in the Time_Series Data Output Table
Data Field
Differential pressure (the difference between
NOTE
NOTE
TABLES 6-7 through 6-14 give a description of all data fields found in each
data output table and when each data field is included in the table.
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.
Variables with _R denote that the value was computed after
coordinate rotations were done. Variables with a _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.
Data Field Name Units Description
Ux m·s-1 Wind speed along sonic x-axis Always
Uy m·s-1 Wind speed along sonic y-axis Always
Uz m·s-1 Wind speed along sonic z-axis Always
T_SONIC deg C Sonic temperature Always
diag_sonic –
CO2 µmol·mol-1 CO2 dry molar mixing ratio Always
H2O
diag_irga –
TA_1_1_1 deg C
T_cell
PA_cell kPa Air pressure inside sample cell Always
CO2_sig_strgth – CO2 signal strength Always
H2O_sig_strgth
PA_diff kPa
PA kPa Ambient pressure Always
pump_flow L·min-1
mmol·mol-1 H2O dry molar mixing ratio
deg C
–
Raw sonic diagnostic value (0 indicates no
diagnostic flags set)
Raw gas analyzer diagnostic value (0 indicates no
diagnostic flags set)
Air temperature calculated from sonic
temperature and humidity
Sample cell temperature
H2O signal strength
sample cell pressure and ambient pressure)
Volumetric air flow to pump; if using vortex
intake, this includes sample flow and vortex
bypass flow
Included
Always
Always
Always
Always
Always
Always
Always
Always
57
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-7. Data Fields in the Time_Series Data Output Table
TABLE 6-8. Data Fields in the Diagnostic Output Table
Data Field
EC155 error flag (set to TRUE or -1 if any irga
Data Field Name Units Description
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
sampling_regime
FW deg C
Binary
number
computing fluxes, filter all values not equal to 1.
(1 corresponds to site 1 which is sampling
ambient air with no omit flag set.) See Appendix
B for more information on sampling regimes and
sites.
Air temperature measured by fine-wire
thermocouple
Data Field
Included
If system is a
CPEC310
If FW05, FW1, or
FW3 is used
Data Field Name Description
System diagnostic word. If 0, no system errors
system_diag
sonc_er
irga_er
pump_tmpr_er Pump temperature error flag Always
pump_flow_er Pump flow error flag Always
valv_tmpr_er Valve temperature error flag
valv_flow_er Valve flow error flag If CPEC310
scrb_tmpr_er Scrub temperature error flag
diag_sonic
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 Temp diagnostic flag Always
sonic_aq_sig_f Acquiring signal diagnostic flag Always
sonic_cal_err_f Calibration error diagnostic flag Always
diag_irga
irga_bad_data_f Any gas analyzer diagnostic flag is set Always
irga_gen_fault_f General system fault diagnostic flag Always
detected. See Appendix C for more details on
system diagnostic.
Sonic error flag (set to TRUE or -1 if any sonic
diagnostic flag detected)
diagnostic flag detected)
CSAT3A diagnostic word. If 0, no error flags set.
See EC155 user manual for more details.
EC155 diagnostic word. If 0, no error flags set.
See EC155 user manual more details.
Included
Always
Always
Always
If CPEC310 with
valve module
If scrub module
used
Always
Always
58
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-8. Data Fields in the Diagnostic Output Table
TABLE 6-9. Data Field in the EC100_Config_Notes Output Table
Data Field Name
Units
Description
Data Field Included
Data Field
Data Field Name Description
Included
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_amb_tmpr_f Ambient temperature probe diagnostic flag Always
irga_amb_press_f Ambient pressure diagnostic flag Always
irga_CO2_I_f CO2 I signal diagnostic flag Always
irga_CO2_Io_f CO2 Io signal diagnostic flag Always
irga_H2O_I_f H2O I signal diagnostic flag Always
irga_H2O_Io_f H2O Io signal diagnostic flag Always
irga_CO2_Io_var_f CO2 Io variation diagnostic flag Always
irga_H2O_Io_var_f H2O Io 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
signal strength (service sample cell when
CO
CO2_sig_strgth
H2O_sig_strgth
2
<80%, see EC155 user manual)
O signal strength (service sample cell when
H
2
<80%, see EC155 user manual)
Always
Always
Config_type String
mode String
site String
bandwidth_freq Hz
A string indicating why the EC100 was
reconfigured
A string indicating the sampling mode. See
Appendix B for more details on modes.
A string indicating the sampling site. See
Appendix B for more details on sites.
EC100 bandwidth (5, 10, 12, or 20 for 5
Hz, 10 Hz, 12.5 Hz, or 20 Hz respectively)
Always
If system is a
CPEC310
If system is a
CPEC310
Always
59
TABLE 6-9. Data Field in the EC100_Config_Notes Output Table
Data Field Name
Units
Description
Data Field Included
press_source –
A parameter indicating whether the sample
A parameter indicating the sensor used by
TABLE 6-10. Data Fields in the Flux_AmeriFluxFormat Output Table
Data Field
diff_press_select –
sample_cell_press_type –
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
A parameter indicating the sensor used by
EC100 for ambient pressure (0 for EC100
Basic Barometer, 1 for user/custom
barometer, 2 for EC100 Enhanced
Barometer)
A parameter indicating whether to report
ambient pressure (open-path system) or
differential pressure (closed-path system). It
should be set to 2, which will auto-select.
cell pressure sensor is differential or
absolute. Set to 0 for EC155 gas head serial
numbers less than 2000, and set to 1 for
serial numbers 2000 and greater.
Always
Always
Always
tmpr_source –
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 µmol·mol-1 CO2 mixing 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
EC155_pwr_off -
CR6_Volts V
Heater_volts V
Shadow_corr –
EC100 for ambient temperature (0 for
EC100 Temperature Probe, no other values
valid)
A parameter indicating whether the EC155
gas head is in sleep or power-down mode.
Set to 0 for power on; set to 1 for power off.
Battery voltage as measured at the CR6
battery input terminal
Heater Control Setting (–1 for disabled, –2
for auto control)
Application of transducer shadowing
correction (0 for off, 1 for on)
Always
Always
Always
Always
Always
Data Field Name Units Description
TIMESTAMP_START YYYYMMDDHHMM Start time of the averaging period Always
TIMESTAMP_END YYYYMMDDHHMM End time of the averaging period Always
CO2 µmol·mol-1 CO2 flux after corrections Always
CO2_SIGMA µmol·mol-1 Standard deviation of CO2 Always
Included
60
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-10. Data Fields in the Flux_AmeriFluxFormat Output Table
Result of steady state and integral
Data Field
Data Field Name Units Description
H2O mmol·mol-1
Average H
(dry basis)
O molar mixing ratio
2
Included
Always
H2O_SIGMA mmol·mol-1 Standard deviation of H2O Always
FC µmol·m-2·s-1 CO2 flux after corrections Always
Result of steady state and integral
FC_SSITC_TEST –
turbulence characteristics for FC
Always
according to Foken et al. (2004)
LE W·m-2 Latent heat flux after corrections Always
Result of steady state and integral
LE_SSITC_TEST –
turbulence characteristics for LE
Always
according to Foken et al. (2004)
ET mm·hour-1 Evapotranspiration Always
Result of steady state and integral
ET_SSITC_TEST –
turbulence characteristics for ET
Always
according to Foken et al. (2004)
H W·m-2
Sensible heat flux after
corrections
Always
H_SSITC_TEST –
turbulence characteristics for FC
Always
according to Foken et al. (2004)
G W·m-2
SG W·m-2
Calculated heat flux at the ground
surface
The change in heat storage in the
soil above the soil heat flux plates
during the averaging interval
If energy balance
sensors used
If energy balance
sensors used
Distance upwind where the
FETCH_MAX m
maximum contribution to the
Always
footprint is found
Upwind distance that contains
90% of cumulative footprint. If
FETCH_90 m
NAN is returned, integration of
the model never reached 90%
Always
within the allowable distance of
integration.
FETCH_55 m
FETCH_40 m
Upwind distance that contains
55% of footprint
Upwind distance that contains
40% of footprint.
Always
Always
WD decimal degrees Average wind direction Always
WS m·s-1 Average wind speed Always
WS_MAX m·s-1 Maximum wind speed Always
USTAR m·s-1 Friction velocity Always
ZL – Stability Always
61
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-10. Data Fields in the Flux_AmeriFluxFormat Output Table
Result of steady state and integral
Standard deviation of atmospheric
Data Field Name Units Description
TAU kg·m-1·s-2 Momentum Flux Always
Data Field
Included
TAU_SSITC_TEST –
turbulence characteristics for FC
Always
according to Foken et al. (2004)
MO_LENGTH m Monin-Obukhov length Always
U m·s-1 Average streamwise wind Always
U_SIGMA m·s-1
Standard deviation of streamwise
wind
Always
V m·s-1 Average crosswind Always
V_SIGMA m·s-1 Standard deviation of crosswind Always
W m·s-1 Average vertical wind Always
W_SIGMA m·s-1
Standard deviation of vertical
wind
Always
PA kPa Average atmospheric Pressure Always
PA_SIGMA kPa
Pressure
Always
Average air temperature
TA_1_1_1 deg C
calculated from sonic temperature
O mixing ratio
and H
2
Always
Standard deviation of air
TA_SIGMA_1_1_1 deg C
temperature calculated from sonic
temperature and H
O mixing ratio
2
Always
Average relative humidity
RH_1_1_1 %
calculated from TA_1_1_1, H
O
2
Always
mixing ratio, and pressure.
Average dewpoint temperature
T_DP_1_1_1 deg C
calculated from H
O mixing ratio
2
Always
and pressure.
TA_2_1_1 deg C
RH_2_1_1 %
T_DP_2_1_1 deg C
Average air temperature
measured by temp/RH probe
Average relative humidity
measured by temp/RH probe
Average dewpoint temperature
calculated from temp/RH probe
If temp/RH probe
If temp/RH probe
If temp/RH probe
measurements
VPD hPa Vapor pressure deficit
If temp/RH probe
T_SONIC deg C Average sonic temperature Always
T_SONIC_SIGMA deg C
PBLH m
Standard deviation of sonic
temperature
Estimated planetary boundary
layer height
Always
Always
used
used
used
used
62
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-10. Data Fields in the Flux_AmeriFluxFormat Output Table
If NR01 or CNR4
TABLE 6-11. Data Fields in the Flux_CSFormat Data Output Table
Data Field Name
Units
Description
Data Field Included
Data Field
Data Field Name Units Description
Average volumetric soil water
SWC_x_1_1 %
TS_x_1_1 deg C
ALB – Albedo
NETRAD W·m-2 Net radiation
PPFD_IN µmol·m-2·s-1 Photosynthetic photon density If LI190 used
SW_IN W·m-2 Incoming shortwave radiation
content. x is an index for the
number of sensors.
Average soil temperature. x is an
index for the number of soil
temperature measurements made.
Included
If CS650 or CS655
If TCAV or CS65X
If NR01 or CNR4
If NR01, CNR4 or
NRLITE2 used
If NR01, CNR4,
LI200, or CS300
used
used
used
used
SW_OUT W·m-2 Outgoing shortwave radiation
LW_IN W·m-2 Incoming longwave radiation
LW_OUT W·m-2 Outgoing longwave radiation
P mm Precipitation in output interval If TE525 used
T_CANOPY deg C Canopy temperature If SI111 used
FC µmol·m-2·s-1 Final corrected CO2 flux Always
FC_mass mg·m-2·s-1 Final corrected CO2 flux Always
Overall quality grade for Fc_molar
FC_QC grade
FC_samples count
LE W·m-2 Final corrected latent heat flux Always
LE_QC grade
LE_samples count
H W·m-2
and Fc_mass following Foken et al.
2012. See Appendix D for quality
grade definitions.
The total number of time series
samples used in calculation of Fc
Overall quality grade for LE following
Foken et al. 2012. See Appendix D for
quality grade definitions.
The total number of time series
samples used in calculation of LE
Final corrected sensible heat flux
derived from sonic sensible heat flux
used
If NR01 or CNR4
used
If NR01 or CNR4
used
Always
Always
Always
Always
Always
63
TABLE 6-11. Data Fields in the Flux_CSFormat Data Output Table
Data Field Name
Units
Description
Data Field Included
H_QC grade
Final corrected sensible heat flux
The total number of time series
If FW05, FW1, or FW3
The ratio of final sensible heat flux
H_samples count
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Overall quality grade for Hs following
Foken et al. 2012. See Appendix D for
Always
quality grade definitions.
The total number of time series
samples used in calculation of H
Always
H_FW W·m-2
H_FW_samples count
NETRAD W·m-2
G W·m-2 Heat flux at the ground surface
SG W·m-2
energy_closure fraction
poor_energy_closure_flg –
Bowen_ratio fraction
TAU kg·m-1·s-2 Final corrected momentum flux Always
TAU_QC grade
USTAR m·s-1
TSTAR deg C
TKE m2·s-2
TA_1_1_1 deg C
TA_SIGMA_1_1_1 deg C
derived from fine-wire thermocouple
measurements
samples used in calculation of H_FW
Average net radiation (corrected for
wind)
The change in heat storage in the soil
above the soil heat flux plates during
the averaging interval
The ratio of sensible and latent heat
fluxes over surface heat flux plus net
radiation
If TRUE (non-zero), energy closure
is poor even though
micrometeorological conditions are
reasonably good with no precipitation
over final latent heat flux
Overall quality grade for tau following
Foken et al. 2012. See Appendix D for
quality grade definitions.
Friction velocity after coordinate
rotations and frequency corrections
Scaling temperature after coordinate
rotations, frequency corrections, and
SDN correction
Specific turbulence kinetic energy
after coordinate rotations
Average ambient temperature
calculated from sonic temperature and
O mixing ratio
H
2
Standard deviation of ambient
temperature calculated from sonic
temperature and H
O mixing ratio
2
If FW05, FW1, or FW3
is used
is used
If NR-LITE2, NR01, or
CNR4 is used
If energy balance
sensors are used
If energy balance
sensors used
If energy balance
sensors are used
If energy balance
sensors and rain gauge
are used
Always
Always
Always
Always
Always
Always
Always
64
TABLE 6-11. Data Fields in the Flux_CSFormat Data Output Table
Data Field Name
Units
Description
Data Field Included
RH_1_1_1 %
Average relative humidity measured
Average crosswind speed after
T_DP_1_1_1 deg C
e kPa
e_sat kPa
TA_2_1_1 deg C
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Relative humidity calculated from
TA_1_1_1, H2O mixing ratio, and
Always
pressure.
Average dewpoint temperature
calculated using H2O mixing ratio and
Always
ambient pressure
Average water vapor pressure
calculated using H2O mixing ratio and
Always
ambient pressure
Average saturated water vapor
pressure calculated using TA_1_1_1
Always
and ambient pressure
Average ambient temperature
measured by temp/RH probe
If temp/RH probe used
RH_2_1_1 %
by temp/RH probe
If temp/RH probe used
Average dewpoint temperature
T_DP_2_1_1 deg C
calculated using temp/RH probe
If temp/RH probe used
measurements
Average water vapor pressure
e_probe kPa
calculated from temp/RH probe
If temp/RH probe used
measurements
Average saturated water vapor
e_sat_probe kPa
pressure calculated from temp/RH
If temp/RH probe used
probe measurements
Average water vapor density
H2O_probe g·m
-3
calculated from temp/RH probe
If temp/RH probe used
measurements
PA kPa Average ambient air pressure Always
PA_SIGMA kPa
Standard deviation of ambient air
pressure
VPD kPa Average vapor pressure deficit Always
U m·s
U_SIGMA m·s-1
-1
Mean streamwise wind speed after
coordinate rotations
Standard deviation of streamwise
wind after coordinate rotations
Always
Always
Always
V m·s-1
V_SIGMA m·s-1
W m·s-1
W_SIGMA m·s-1
T_SONIC deg C Average sonic temperature Always
coordinate rotations
Standard deviation of crosswind after
coordinate rotations
Average vertical wind speed after
coordinate rotations
Standard deviation of vertical wind
after coordinate rotations
Always
Always
Always
Always
65
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-11. Data Fields in the Flux_CSFormat Data Output Table
Data Field Name
Units
Description
Data Field Included
decimal
Compass direction in which the sonic
decimal
Standard deviation of CO2 dry molar
Average fine-wire thermocouple
If FW05, FW1, or FW3
If LI200, CS300,
T_SONIC_SIGMA deg C
sonic_azimuth
degrees
Standard deviation of sonic
temperature
negative x-axis points
Always
Always
WS m·s-1 Average wind speed Always
WS_RSLT m·s-1 Average horizontal wind speed Always
WD_SONIC
WD_SIGMA
WD
WS_MAX m·s
decimal
degrees
degrees
decimal
degrees
-1
CO2 µmol·mol
CO2_SIGMA µmol·mol
Average wind direction in the sonic
coordinate system
Always
Standard deviation of wind direction Always
Average compass wind direction Always
Maximum wind speed Always
-1
Average CO
-1
mixing ratio
dry molar mixing ratio Always
2
Always
CO2_density mg·m-3 Average CO2 mass density Always
CO2_density_SIGMA mg·m-3
Standard deviation of CO
density
mass
2
Always
H2O mmol·mol-1 Average H2O dry molar mixing ratio Always
H2O_SIGMA mmol·mol-1
Standard deviation of H2O dry molar
mixing ratio
Always
H2O_density mmol·mol-1 Water vapor mass density Always
H2O_density_SIGMA mmol·mol-1
Standard deviation of water vapor
mass density
Always
CO2_sig_strgth_Min – Minimum CO2 signal strength Always
H2O_sig_strgth_Min – Minimum H2O signal strength Always
FW deg C
FW_SIGMA deg C
P mm Total precipitation If TE525MM is used
NETRAD_meas W·m-2
ALB – Average albedo
SW_IN W·m-2
SW_OUT W·m-2
temperature
Standard deviation of fine-wire
thermocouple temperature
Average net radiation (raw, not
corrected for wind)
Average incoming short wave
radiation
Average outgoing short wave
radiation
is used
If FW05, FW1, or FW3
is used
If NR-LITE2 is used
If CNR4 or NR01
is used
CNR4, or NR01
is used
If CNR4 or NR01
is used
66
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-11. Data Fields in the Flux_CSFormat Data Output Table
Data Field Name
Units
Description
Data Field Included
If CNR4 or NR01
Average raw incoming long wave
If CNR4 or NR01
decimal
decimal
LW_IN W·m-2
LW_OUT W·m-2 Average outgoing long wave radiation
T_nr K Average sensor body temperature
R_LW_in_meas W·m-2
R_LW_out_meas W·m-2
PPFD_IN µmol·s-1·m-2
sun_azimuth
sun_elevation
hour_angle
sun_declination
air_mass_coeff –
daytime fraction
T_CANOPY deg C
T_SI111_body deg C Average temperature of sensor body If SI111 is used
TS_x_1_1 deg C
SWC_x_1_1 m3·m-3
CS65x_ec_x_1_1 dS·m-1
G_PLATE_x_1_1 W·m-2
shfp_cal_x_1_1 W m-2 mV-1
decimal
degrees
degrees
decimal
degrees
degrees
Average incoming long wave
radiation
radiation
Average raw outgoing long wave
radiation
Average density of photosynthetic
active radiation
Solar azimuth Always
Solar elevation Always
Solar hour angle Always
Solar declination Always
Air mass coefficient: Ratio of the path
length between the current solar
position to the solar noon
Day time in fraction of an output
interval
Average temperature of targeted
object
Average soil temperature for each soil
temperature sensor; x is an index for
the number of sensors
Average volumetric soil water content
for each CS650 or CS655; x is an
index for the number of each sensor
model above
Average electrical conductivity for
each sensor; x is an index for the
number of CS650 or CS655
Average heat flux through plate; x is
an index for the number of HFP01 or
HFP01SC
Coefficients found from the HFP01SC
self-calibration and used to calculate
shf_plate_x_1_1; x is an index for the
number of HFP01 or HFP01SC
If CNR4 or NR01
is used
is used
If CNR4 or NR01
is used
is used
If CNR4 or NR01
is used
If LI190 is used
Always
Always
If SI111 is used
If TCAV or CS650 or
CS655 is used
If CS650 or CS655
sensors
are used
If CS650 or CS655
is used
If HFP01 or HFP01SC
is used
If HFP01SC is used
67
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-11. Data Fields in the Flux_CSFormat Data Output Table
Data Field Name
Units
Description
Data Field Included
Upwind distance that contains 90% of
Upwind distance that contains 40% of
Upwind distance of interest for the
Returns either Kljun or
TABLE 6-12. Data fields in the Flux_Notes Output Table
FETCH_MAX m
FETCH_90 m
FETCH_55 m
FETCH_40 m
UPWND_DIST_INTRST m
FTPRNT_DIST_INTRST %
FTPRNT_EQUATION text
Distance upwind where the maximum
contribution to the footprint is found
cumulative footprint
Upwind distance that contains 55% of
footprint
footprint. If NAN is returned,
integration of the model never reached
90% within the allowable distance of
integration.
average wind direction
Percentage of footprint from within
the upwind range of interest
KormannMeixner; the model of
Kljun et al. (2004) is used for
applicable atmospheric conditions,
else the model of Kormann & Meixner
(2001) is used.
Always
Always
Always
Always
Always
Always
Always
Data Field Name Units Description
Ux
Ux_SIGMA
Uy m·s
Uy_SIGMA
Uz
Uz_SIGMA m·s
UxUy_cov m2·s-2 Covariance of Ux and Uy Always
UxUz_cov m2·s-2 Covariance of Ux and Uz Always
UyUz_cov m2·s-2 Covariance of Uy and Uz Always
TsUx_cov deg C·m·s-1 Covariance of Ts and Ux Always
TsUy_cov deg C·m·s-1 Covariance of Ts and Uy Always
TsUz_cov deg C·m·s-1 Covariance of Ts and Uz Always
USTAR_R m·s-1
UV_cov m·s-1
-1
m·s
m·s
m·s
m·s
-1
-1
-1
-1
-1
Average U
Standard deviation of U
x
x
Average Uy Always
Standard deviation of U
Average U
z
y
Standard deviation of Uz Always
Friction velocity after coordinate
rotations
Covariance of streamwise and
crosswind after coordinate rotations
Data Field
Included
Always
Always
Always
Always
Always
Always
68
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
Covariance of streamwise wind and
Covariance of crosswind and sonic
Number of sonic samples with
Data Field Name Units Description
UW_cov m·s-1
VW_cov m·s-1
Covariance of streamwise and
crosswind after coordinate rotations
Covariance of crosswind and vertical
wind after coordinate rotations
Data Field
Included
Always
Always
UT_SONIC_Cov m·°C·s-1
VT_SONIC_Cov m·°C·s-1
WT_SONIC_Cov m·°C·s-1
UW_Cov_fc m2·s-2
VW_Cov_fc m2·s-2
WT_SONIC_Cov_fc m·°C·s-1
WT_SONIC_Cov__fc_SND m·°C·s-1
sonic_samples count
no_sonic_head_Tot count
no_new_sonic_data_Tot count
sonic temperature after coordinate
rotations
temperature after coordinate rotations
Covariance of vertical wind (after
coordinate rotations) and sonic
temperature
Covariance of streamwise and vertical
wind after coordinate rotations and
frequency corrections
Covariance of cross and vertical wind
after coordinate rotations and frequency
corrections
Covariance of vertical wind and sonic
temperature after coordinate rotations
and frequency corrections
Covariance of vertical wind and sonic
temperature after coordinate rotations,
frequency corrections, and SND
correction
Number of raw sonic samples in
averaging period without diagnostic
flags
Number of sonic samples where no
sonic head was detected
Number of scans where no sonic data
were received
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
sonic_amp_l_f_Tot count
sonic_amp_h_f_Tot count
sonic_sig_lck_f_Tot count
sonic_del_T_f_Tot count
sonic_aq_sig_f_Tot count
sonic_cal_err_f_Tot count
amplitude low diagnostic flag
Number of sonic samples with
amplitude high diagnostic flag
Number of sonic samples with signal
lock diagnostic flag
Number of sonic samples with delta
temp diagnostic flag
Number of sonic samples with
acquiring signal diagnostic flag
Number of sonic samples with
calibration error diagnostic flag
Always
Always
Always
Always
Always
Always
69
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
Covariance of Uz and water vapor
Number of scans where no gas analyzer
Data Field
Data Field Name Units Description
Included
UxCO2_Cov mg·m-2·s-1 Covariance of Ux and CO2 density Always
UyCO2_Cov mg·m-2·s-1 Covariance of Uy and CO2 density Always
UzCO2_Cov mg·m-2·s-1 Covariance of Uz and CO2 density Always
UxH2O_Cov g·m-2·s-1
UyH2O_Cov g·m-2·s-1
Covariance of U
density
Covariance of U
density
and water vapor
x
and water vapor
y
Always
Always
UzH2O_Cov g·m-2·s-1
UCO2_Cov mg·m-2·s-1
VCO2_Cov mg·m-2·s-1
WCO2_Cov mg·m-2·s-1
UH2O_Cov g·m-2·s-1
VH2O_Cov g·m-2·s-1
WH2O_Cov g·m-2·s-1
WCO2_Cov_fc mg·m-2·s-1
WH2O_Cov_fc g·m-2·s-1
CO2_samples count
H2O_samples count
no_irga_head_Tot count
density
Covariance of streamwise wind and
density after coordinate rotations
CO
2
Covariance of crosswind and CO
2
density after coordinate rotations
Covariance of vertical wind and CO
density after coordinate rotations
Covariance of streamwise wind and
O density after coordinate rotations
H
2
Covariance of crosswind and H
O
2
density after coordinate rotations
Covariance of vertical wind and H
O
2
density after coordinate rotations
Covariance of vertical wind and CO
density after coordinate rotations and
frequency corrections
Covariance of vertical wind and H
O
2
density after coordinate rotations and
frequency corrections
Number of CO
samples without
2
diagnostic flags, within threshold for
signal strength (set in code to
CO
2
default of 0.7), and within factory
calibrated CO
1000 µmol·mol
Number of H
measurement range (0 to
2
-1
).
O samples without
2
diagnostic flags, within threshold for
O signal strength (set in code to
H
2
default of 0.7), and within factory
calibrated H
72 mmol·mol
O measurement range (0 to
2
-1
).
Number of samples where no gas
analyzer head was detected
Always
Always
Always
2
Always
Always
Always
Always
2
Always
Always
Always
Always
Always
no_new_irga_data_Tot count
data were received
Always
70
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
Number of gas analyzer samples with
Number of gas analyzer samples with
Number of gas analyzer samples with
Number of gas analyzer samples with
Number of gas analyzer samples with
Data Field Name Units Description
irga_bad_data_f_Tot count
irga_gen_fault_f_Tot count
Number of IRGA samples with any
IRGA diagnostic flag set high
Number of gas analyzer samples with
general system fault diagnostic flag
Data Field
Included
Always
Always
irga_startup_f_Tot count
irga_motor_spd_f_Tot count
irga_tec_tmpr_f_Tot count
irga_src_pwr_f_Tot count
irga_src_tmpr_f_Tot count
irga_src_curr_f_Tot count
irga_off_f_Tot count
irga_sync_f_Tot count
irga_amb_tmpr_f_Tot count
irga_amb_press_f_Tot count
irga_CO2_l_f_Tot count
irga_CO2_Io_f_Tot count
irga_H2O_I_f_Tot count
irga_H2O_Io_f_Tot count
irga_CO2_Io_var_f_Tot count
startup diagnostic flag
Number of gas analyzer samples with
motor speed diagnostic flag
TEC temperature diagnostic flag
Number of gas analyzer samples with
source power diagnostic flag
Number of gas analyzer samples with
source temperature diagnostic flag
Number of gas analyzer samples with
source current diagnostic flag
gas head power down diagnostic flag
Number of gas analyzer samples with
synchronization diagnostic flag
Number of gas analyzer samples with
ambient temperature probe diagnostic
flag
ambient pressure diagnostic flag
Number of gas analyzer samples with
1 signal diagnostic flag
CO
2
Number of gas analyzer samples with
signal diagnostic flag
CO
2 Io
Number of gas analyzer samples with
O I signal diagnostic flag
H
2
Number of gas analyzer samples with
O Io signal diagnostic flag
H
2
Number of gas analyzer samples with
variation diagnostic flag
CO
2 Io
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
irga_H2O_Io_var_f_Tot count
irga_CO2_sig_strgth_f_Tot count
irga_H2O_sig_strgth_f_Tot count
irga_cal_err_f_Tot count
H2O Io variation diagnostic flag
Number of gas analyzer samples with
signal strength diagnostic flag
CO
2
Number of gas analyzer samples with
O signal strength diagnostic flag
H
2
Number of gas analyzer samples with
calibration file read error flag
Always
Always
Always
Always
71
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
Data Field
Data Field Name Units Description
irga_htr_ctrl_off_f_Tot count
Number of gas analyzer samples with
heater control off diagnostic flag
Included
Always
Number of gas analyzer samples with
irga_diff_press_f_Tot count
differential pressure out of range
Always
diagnostic flag
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
UxFW_cov deg C·m·s-1
UyFW_cov deg C·m·s-1
UzFW_cov deg C·m·s-1
UFW_cov deg C·m·s-1
VFW_cov deg C·m·s-1
WFW_cov deg C·m·s-1
WFW_cov_fc deg C·m·s-1
FW_samples count
Covariance of U
and fine-wire
x
thermocouple temperature
Covariance of U
and fine-wire
y
thermocouple temperature
Covariance of U
and fine-wire
z
thermocouple temperature
Covariance of streamwise wind and
fine-wire thermocouple temperature
after coordinate rotations
Covariance of crosswind and fine-wire
thermocouple temperature after
coordinate rotations
Covariance of vertical wind and finewire thermocouple temperature after
coordinate rotations
Covariance of vertical wind and finewire thermocouple temperature after
coordinate rotations and frequency
corrections
The number of valid fine-wire
thermocouple measurements in the
averaging period from which
covariances may be calculated
pump_tmpr deg C Average pump temperature Always
Always, but
data are
pump_press kPa Average pump pressure
excluded
during CO
or H
Always, but
data are
excluded
during CO
pump_flow_duty_cycle Adimensional
Average pump duty cycle (0 is off, and
1 is full power)
or H
pump_flow_set_pt kPa Pressure set point of the sample cell Always
pump_heater_secs s
Number of seconds in the interval that
the pump heater was on
Always
O span
2
O span
2
2
2
72
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
If the system
If the system
If the system
The differential pressure; that is, the
Average volumetric flow to pump (sum
Average saturation vapor pressure
Data Field Name Units Description
pump_fan_secs s
valve_tmpr deg C
valve_heater_secs s
valve_fan_secs s
Number of seconds in the interval that
the pump fan was on
Average temperature of the valve
module
Number of seconds in the interval the
valve module heater was on
Number of seconds in the interval the
valve module fan was on
Data Field
Included
Always
If the system
has a valve
module (i.e.
CPEC310)
If the system
has a valve
module (i.e.
CPEC310)
If the system
has a valve
module (i.e.
CPEC310)
scrub_tmpr deg C
scrub_press kPa Average pressure of the scrub module
scrub_heater_secs s
scrub_fan_secs s
cell_tmpr deg C Average temperature of the sample cell Always
cell_tmpr_SIGMA deg C
cell_press kPa Average pressure inside the sample cell Always
cell_press_SIGMA kPa
diff_press kPa
pump_flow L·min-1
pump_flow_SIGMA L·min-1 Standard deviation of pump flow Always
cell_e kPa Average vapor pressure in sample cell Always
cell_T_DP Deg C
Average temperature of the scrub
module
Number of seconds in the interval that
the scrub module heater was on
Number of seconds in the interval that
the scrub module fan was on
Standard deviation of the sample cell
temperature
Standard deviation of the sample cell
pressure
difference in pressure between the
sample cell and ambient
of sample flow and vortex bypass flow)
Average dew point temperature inside
sample cell
has a scrub
module
has a scrub
module
If the system
has a scrub
module
has a scrub
module
Always
Always
Always
Always
Always
cell_e_sat kPa
inside sample cell
Always
73
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
User entered measurement height of EC
Data Field Name Units Description
cell_RH %
alpha
beta
gamma
decimal
degrees
decimal
degrees
decimal
degrees
Average relative humidity inside sample
cell
Alpha angle used for coordinate
rotations (regardless of planar fit or
double rotation method, angle
convention of Wilczak et al. 2001 used)
Beta angle used for coordinate rotations
(regardless of planar fit or double
rotation method, angle convention of
Wilczak et al. 2001 used)
Gamma angle used for coordinate
rotations (regardless of planar fit or
double rotation method, angle
convention of Wilczak et al. 2001 used)
Data Field
Included
Always
Always
Always
Always
height_measurement m
height_canopy m User entered canopy height Always
surface_type_text text User entered surface type Always
displacement_user m
d m
roughness_user m
z0 m
z m Aerodynamic height Always
MO_LENGTH m Monin-Obukhov length Always
ZL m·m-1 Atmospheric surface layer stability Always
iteration_FreqFactor count
latitude
longitude
decimal
degrees
decimal
degrees
sensors
User entered displacement height; 0 for
auto calculation
Displacement height used in
calculations; it will equal
displacement_user if user entered a nonzero value; if displacement_user is zero,
program will auto calculate
User entered roughness length; 0 for
auto calculation
Roughness length used in calculations;
it will equal roughness_use if user
entered a non-zero value; if
roughness_user is zero, program will
auto calculate
Number of iterations for recalculating
Monin-Obukhov length and frequency
factors
Latitude; positive for Nothern
hemisphere, negative for Southern
hemisphere
Longitude; positive for Eastern
hemisphere, negative for Western
hemisphere
Always
Always
Always
Always
Always
Always
Always
Always
74
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
Time offset in hours between local time
Separation between sonic and gas
Separation between sonic and fine-wire
If FW05,
If FW05,
Separation distance between sonic and
If FW05,
Number of scans to lag fine-wire
Data Field Name Units Description
altitude m Altitude or elevation above sea level Always
Data Field
Included
UTC_offset hr
separation_x_irga m
separation_y_irga m
separation_lat_dist_irga m
separation_lag_dist_irga m
separation_lag_scan_irga scans
separation_x_FW m
separation_y_FW m
FW_diameter m
zone and UTC/GMT
Separation between sonic and gas
analyzer with respect to sonic x-axis
analyzer with respect to sonic y-axis
Separation distance between sonic and
gas analyzer along the axis
perpendicular to oncoming wind
Separation distance between sonic and
gas analyzer along the axis parallel to
oncoming wind
Number of scans to lag gas analyzer
data relative to sonic data to account for
separation along the axis of oncoming
wind and wind velocity
thermocouple with respect to sonic xaxis
Separation between sonic and fine-wire
thermocouple with respect to sonic yaxis
Effective diameter of fine-wire
thermocouple junction
Always
Always
Always
Always
Always
Always
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
FW1, or
FW3 is used
separation_lat_dist_FW m
separation_lag_dist_FW m
separation_lag_scan_FW scans
time_const_FW m
fine-wire thermocouple along axis
perpendicular to oncoming wind
Separation distance between sonic and
fine-wire thermocouple along axis
parallel to oncoming wind
thermocouple data relative to sonic data
to account for separation along axis of
oncoming wind and wind velocity
Calculated time constant of the finewire thermocouple
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
If FW05,
FW1, or
FW3 is used
75
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
Data Field Name Units Description
Maximum number of scans to lag gas
analyzer or fine-wire thermocouple data
with respect to sonic data when doing
MAX_LAG scans
cross correlation for covariance
maximization. For example, if
MAX_LAG = 2, the program will
consider lags of −2, −1, 0, +1, and +2.
The lag applied to CO
lag_CO2 scans
respect to sonic data that maximizes
covariance
The lag applied to H
lag_H2O Scans
respect to sonic data that maximizes
covariance
The lag applied to fine-wire
lag_FW scans
thermocouple data with respect to sonic
data that maximizes covariance
FreqFactor_UW_VW number
FreqFactor_WT_SONIC number
FreqFactor_WCO2 number
FreqFactor_WH2O Number
Frequency correction factor applied to
momentum fluxes
Frequency correction factor applied to
wTs covariance
Frequency correction factor applied to
covariance
wCO
2
Frequency correction factor applied to
O covariance
wH
2
Frequency correction factor applied to
FreqFactor_WFW number
fine-wire thermocouple derived wFW
covariance
rho_d g·m-3
rho_a kg·m-3
rho_d_probe g·m
-3
Average density of dry air calculated
from EC sensors
Average density of ambient moist air
calculated from EC sensors
Average density of dry air calculated
from temp/RH probe measurements
Average density of ambient moist air
rho_a_probe kg·m
-3
calculated from temp/RH probe
measurements
Cp J·kg
-1·K-1
Specific heat of ambient (moist) air at
constant pressure
Lv J·g-1 Latent heat of vaporization Always
T_panel deg C
Average temperature of the datalogger
wiring panel
data with
2
O data with
2
Data Field
Included
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
Always
If a temp/RH
probe is used
If a temp/RH
probe is used
Always
Always
76
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-12. Data fields in the Flux_Notes Output Table
Number of slow sequences during the
TABLE 6-13. Data Fields in the Zero_Span_Notes Table
Data Field Name
Units
Description
Data Field Included
Data Field Name Units Description
Average panel temperature of the
CDM-A116, where x at the end of the
T_panel_CDMA_x Deg C
name is an index from 1 to 4,
representing the each of the thermistors
under the terminal strips of the CDMA116
batt_volt volt
Average battery voltage supplying
power to the datalogger
Data Field
Included
If a CDM-
A116 is used
Always
slowsequence_Tot count
averaging interval (for example, the
number of times biomet and energy
Always
balance sensors were measured)
process_time ms Average processing time for each scan Always
process_time_SIGMA
ms
Standard deviation of scan time
Always
process_time_Max ms Maximum processing time for a scan Always
process_time_Min
buff_depth number
buff_depth_Max number
ms
Minimum processing time for a scan
Average number of records stored in the
buffer
Maximum number of records stored in
the buffer
Always
Always
Always
CO
gain factor
2
CO2_gain Adimensional
[CO2_span_gas/(CO2_span –
Always
CO2_zero)]
H
O gain factor
2
H2O_gain Adimensional
[H2O_span_gas/(H2O_span –
Always
H2O_zero)]
CO2_zero µmol∙mol-1
H2O_zero mmol∙mol-1
CO
2
offset)
O mixing ratio during zero (i.e.,
H
2
offset)
Always
Always
mixing ratio during zero (i.e.,
cell_tmpr_zero ° C Sample cell temperature during zero Always
cell_press_zero kPa Sample cell pressure during zero Always
scrub_press_zero kPa
Scrub module gauge pressure during
zero
If scrub module used
CO2_sig_strgth_zero Adimensional CO2 signal strength during zero Always
H2O_sig_strgth_zero Adimensional H2O signal strength during zero Always
diff_press_zero kPa
Pressure difference between sample
cell and ambient during zero
Always
77
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-13. Data Fields in the Zero_Span_Notes Table
Data Field Name
Units
Description
Data Field Included
Dew point set point on the dew point
valve_flow_zero L∙min-1 Flow rate of zero air during zero Always
CO2_CO2span µmol∙mol-1
H2O_CO2span mmol∙mol-1
cell_tmpr_CO2span °C
Measured CO
span
CO
2
Measured H
span
CO
2
Sample cell temperature during CO
span
mixing ratio during
2
O mixing ratio during
2
Always
Always
2
Always
cell_press_CO2span kPa Sample cell pressure during CO2 span Always
CO2_sig_strgth_CO2span Adimensional CO2 signal strength during CO2 span Always
H2O_sig_strgth_CO2span Adimensional H2O signal strength during CO2 span Always
diff_press_CO2span kPa
valve_flow_CO2span L∙min-1
Pressure difference between sample
cell and ambient during CO
Flow rate of CO
span gas during CO2
2
span
2
span
Always
Always
CO2_span_gas µmol∙mol-1 CO2 mixing ratio of CO2 span gas Always
Td_span_gas °C
generator providing the H2O span gas
Always
H2O_span_gas mmol∙mol-1 Mixing ratio of H2O span gas Always
valve_flow_set_pt kPa Vapor pressure of H2O span gas Always
zeroing_outof_spec_f Boolean
CO2span_outof_spec_f Boolean
H2Ospan_outof_spec_f Boolean
CO2_zero_coeff Adimensional
CO2_span_coeff Adimensional
H2O_zero_coeff Adimensional
H2O_span_coeff Adimensional
Indicator of whether zeroing is
necessary
Inidcator of whether CO
span is
2
necessary
Indicator of whether H
O span is
2
necessary
Value of zero coefficient used in the
gas analyzer’s CO
algorithm
2
Value of the span coefficient used in
the ga analyzer’s CO
algorithm
2
Value of the zero coefficient used in
the gas analyzer’s H
O algorithm
2
Value of the span coefficient used in
the gas analyzer’s H
O algorithm
2
Always
Always
Always
If zero or spans are
being set (not just
If zero or spans are
being set (not just
If zero or spans are
being set (not just
If zero or spans are
being set (not just
read)
read)
read)
read)
78
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 6-14. Data Field in the System_Operatn_Notes Output Table
Data Field Name
Units
Description
Data Field Included
Text
Additional information corresponding to the
Message
Current Value
Previous Value
Text
string
string
Text
String
A message describing a change of system
status
Message
Additional information corresponding to the
Message
Always
Always
Always
6.6 Program Sequence of Measurement and Corrections
The main correction procedures and algorithms implemented into the program
are listed below. For a more detailed, stepwise description of measurements
made and corrections applied, refer to Appendix A, EasyFlux DL CR6CP
Process Flow
1. Despike and filter raw time series data using sonic and gas analyzer
2. Coordinate rotations with an option to use the double rotation method
3. Lag CO
(p. A-1).
diagnostic codes, and signal strength and measurement output range
thresholds.
(Tanner and Thurtell 1969), or planar fit method (Wilczak et al.
2001).
and H2O measurements relative to sonic wind measurements
2
for maximization of CO
and H2O covariances (Horst and Lenschow
2
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 et al. 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. 2016).
5. A modified SND correction (Schotanus et al. 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 may be
provided.
6. Data quality qualifications based on steady state conditions, surface-
layer turbulence characteristics, and wind directions following Foken
et al. 2012 (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.
79
The appendices in the EasyFlux DL CR6OP manual describe the
NOTE
NOTE
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. 2016, 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.
7. 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 H
all determined by user-entered constants relating to a CPEC310 (see constants
that are indented under the constant “CPEC310” in TABLE 6-1, Program
Constants). An automatic zero and span cycle on a CPEC310 may be manually
initiated at any time; instructions to do so are found in Section 7.1, UserInitiated Zero/Span for CPEC310
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
8. Footprint characteristics are computed using Kljun et al (2004) and
Kormann and Meixner (2001).
O span, are
2
(p. 84).
For CPEC310 systems that are not set up with a continuously available source
of H
O span gas, which is typically the case, H2O spans must be manually
2
setup and initiated by the user. More details are found in Section 7.1.2,
CPEC310 Manual H2O Span
(p. 86).
CPEC300 and CPEC306 systems require the user to manually setup and
initiate the zero, CO
span, and/or H2O span since these systems do not include
2
a valve module. More details are found under Section 7.2, User-Initiated
Manual Zero/Span for CPEC300 or CPEC306
(p. 87).
Regardless of system type, perfoming 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 datalogger and while the program is
running. Pressing Enter twice will access the main menu. Under the main
menu, use the keypad’s down arrow to scroll down until the submenu
Attendant Zero/Span is highlighted and press Enter. This menu accesses all
menus and variables needed for doing a zero and span as explained in the
sections below.
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 user manual.
For reference, FIGURE 6-2 shows an organizational schematic for
all the keypad menus. To return to a previous menu at any time,
press Esc.
80
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 7-1. Variables Found in Menus for Zero and Span
Variable Name
Default
Description
CR1000KD available)
NOTE
NOTE
TABLE 7-1
Zero/Span menu and its submenus. The table also shows the
equivalent variable names in the datalogger’s 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 Numberic Display that includes all of
the variables in
sections above, substituting public table variable names (last
column in TABLE 7-1) for the variable names in the menus (first
colum in TABLE 7-1
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.
Valv Tmpr Ok -
Valv Tmpr -
Scrb Tmpr Ok -
lists the variables found within the Attendant
TABLE 7-1. Follow the instructions in the
).
Name of variable in
Public Table (when no
This is a TRUE/FALSE readonly variable. It must read
TRUE in order to perform an
auto zero/span. If it reports
FALSE, the valve module
temperature is not within its
operating range and Valv T Ctl
On should be set to TRUE to
bring the temperature within
range. This variable is ommitted
if the system is not a CPEC310.
This is a read-only variable
showing the temperature in °C of
the valve module. This variable
is ommitted if the system is not a
CPEC310.
This is a TRUE/FALSE readonly variable. It must read
TRUE in order to perform an
auto zero using the scrub module
as the zero gas source. If it
reports FALSE, the 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. This variable is ommitted
if the system does not have a
scrub module.
valve_tmpr_ok
valve_tmpr
scrub_tmpr_ok
81
TABLE 7-1. Variables Found in Menus for Zero and Span
Variable Name
Default
Description
CR1000KD available)
Scrb Tmpr -
The dry molar mixing ratio of the
Val T Ctl On
(If scrub module
included, variable
name is
V/S T Ctl On)
FALSE
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Name of variable in
Public Table (when no
This is a read-only variable
showing the temperature in °C of
the scrub module. This variable
scrub_tmpr
is ommitted if the system does
not have a scrub module.
Set this variable to TRUE to
enable temperature control
(heaters and fans) of the valve
module (and scrub module if
applicable). Following an auto
valve_tmpr_ctrl_flg
zero/span, this variable may be
set back to FALSE to conserve
power.
CO2 Span Gas 400
H2O Span TDP 10
H2O Span Gas -
Pick AUTO_ZS
Pick ZRO_ALL
Pick SPN_CO2
FLD_MEA
Pick SPN_H2O
Site -
CO2 span gas in µmol·mol-1.
The dewpoint temperature
setting on the H
O span gas
2
source in °C.
This is a read-only variable
showing the calculated dry molar
mixing ratio of the H
-1
in mmol·mol
. The air pressure
O span gas
2
difference between ambient and
the dew point generator is taken
into account when calculating.
This variable indicates the
current sampling mode.
Depending on which keypad
menu is viewed, this 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 the auto zero/span cycle.
This is a read-only variable
showing the current sampling
site. Monitor this variable to see
progress of zero/span. See
Appendix B for more details on
sampling sites.
CO2_span_gas
Td_span_gas
H2O_span_gas
mode
Options:
1 = FLD_MEA
3 = ZRO_ALL
4 = SPN_CO2
5 = SPN_H2O
7 = AUTO_ZS
site_
Options: fld smp, offst
P, chk CO2, chk zro, set
zro, set CO2, chk H2O,
set H2O, equilib,
irg_off
82
TABLE 7-1. Variables Found in Menus for Zero and Span
Variable Name
Default
Description
CR1000KD available)
Sec On Site -
This is a variable used to disable
This is a read-only variable
This is a read-only variable
This is a read-only variable
Pump Off
TRUE
TRUE
TRUE
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
Name of variable in
Public Table (when no
This is a read-only variable
showing the number of seconds
the system has been on the
sec_on_site
current site.
Pump Off FALSE
CO2 umol/mol -
H2O Cell TDP -
H2O mmol/mol -
GasFlw L/min -
System Diag -
Do CO2 Span FALSE
Do H2O Span FALSE
Do Zero FALSE
the pump. The pump should be
disabled before conducting a
manual zero or span.
This is a read-only variable
showing the current
measurement of CO
sample cell in µmol·mol
inside the
2
-1
.
showing the current
measurement of dew point
temperature inside the sample
cell in °C.
This is a read-only variable
showing the current
measurement of H
O dry molar
2
mixing ratio inside the sample
-1
cell in mmol·mol
.
showing the current flow in
-1
L·min
through the sample cell.
showing the system diagnostic
word. A non-zero result indicates
an error condition is detected.
For an interpretation of the
system diagnostic word, see
Appendix C.
Change this variable to TRUE to
manually zero the analyzer.
(Zero gas should be flowing and
set to
.)
Change this variable to TRUE to
manually do a CO
analyzer. (CO
span of the
2
span gas should
2
be flowing and Pump Off set to
).
Change this variable to TRUE to
manually do an H
analyzer. (H
O span of the
2
O span gas should
2
be flowing and Pump Off set to
).
pump_off_flg
sonic_irga_raw(6)
cell_T_DP
Sonic_irga_raw(7)
valve_flow
system_diag
do_zero_flg
do_CO2_span_flg
do_H2O_span_flg
83
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
NOTE
7.1 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 the 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’s
temperature and whether it is within safe operating range. If the temperature is
out of range, scroll down to the variable called VAL T Ctl On (or V/S T Ctl
On if using scrub module), press Enter, highlight TRUE, and press Enter.
This will enable the module’s temperature control. Continue to monitor the
module’s temperature readings shown in this menu until they are within
operating range.
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.
7.1.1 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 CO
press Enter, type in the correct value, and press Enter again to save. If the
user-entered CPEC310-related constants were set such that an H
be included in the automatic zero/span cycle (see TABLE 6-1, Program
Constants), also confirm that the value of H2O Span TDP, the H
dewpoint temperature, is correct.
span gas. If it needs to be edited, highlight the variable,
2
O span would
2
O span gas
2
Next, highlight Pick AUTO_ZS, press Enter, make sure AUTO_ZS is
highlighted, and press Enter. This initiates the automatic zero/span cycle;
TABLE 7-2 shows the sequence and timing 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 CO
, H2O, gas
2
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’s measurement mode has returned to normal EC 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.
For more information on sampling modes, regimes, and sites, refer
to Appendix B, Sampling Site, Regime, and Mode (p. B-1).
TABLE 7-2. Site sequence and timing in the auto zero and span cycle. 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 6-1, Program Constants.
84
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 7-2. Site Sequence and Timing in the Auto Zero and Span Cycle
Step in
Omit Status (seconds of
Transition from EC field
10 (i.e., the first 10
CO2 span gas flows from
Zero gas flows from the
Zero gas flows from the
CO2 span gas flows from
H2O span gas flows from
H2O span is set on the
Auto
Zero/Span
Cycle
1
2
3
4
Description
measurements to the
zero/span sequence
The pump is turned off and
the system measures the
offset between the sample
cell pressure sensor and the
ambient pressure sensor.
its tank to the sample cell.
The pump is off. The
system measures CO
does not set CO
to the CO
span gas
2
but
2
readings
2
concentration.
scrub module or a tank to
the sample cell. The pump
is off. The system measure
and H2O but does not
CO
2
set them to zero.
Site
Name
Timing (seconds)
fld smp 1 1
offst P 15
TIME_ZRO_SPN
chk CO2
Default: 60
TIME_ZRO_SPN + 20
chk zro
Default: 80
measurements that are
ommitted from
statistics or stored data)
seconds are ommitted so
the system may
equilibrate. The last 5
seconds of measurements
are used and stored.)
TIME_ZRO_SPN – 5
Default: 55
TIME_ZRO_SPON – 5
Default: 75
5
6
71/
81/
scrub module or a tank to
the sample cell. The pump
is off. The analyzer CO
O measurements are
and H
2
2
zeroed.
the tank to the sample cell.
The pump is off. The CO
2
span is set during the last
10 seconds.
its source to the sample
cell. The pump is off. The
O span is not set, just
H
2
measured.
analyzer.
set zro 10 10
TIME_ZRO_SPN + 30
set CO2
Default: 90
3*TIME_ZRO_SPN
chk H2O
Default: 180
set H2O 10 10
TIME_ZRO_SPN + 30
Default: 90
3*TIME_ZRO_SPN – 5
Default: 175
85
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
TABLE 7-2. Site Sequence and Timing in the Auto Zero and Span Cycle
Step in
Omit Status (seconds of
The system prepares to
1/
Because it is difficult to have an autonomous field H2O span gas source, the constants CHECK_H2OSPN and
Auto
Zero/Span
Cycle
Description
Site
Name
Timing (seconds)
measurements that are
ommitted from
statistics or stored data)
resume operation in normal
EC field measurement
9
mode. All valves to zero
and span gases are closed.
equilib 30 30
The pump is turned on, and
ambient air is pulled
through sample cell.
SET_H2OSPN (see TABLE 6-1, Program Constants) are typically set to FALSE, and these steps in the auto zero/span
sequence are skipped.
7.1.2 CPEC310 Manual H2O Span
If the CPEC310 automatic zero/span cycle does not include an H2O span, a
manual H
The user must first connect tubing from an H
generator) to the H
the dewpoint generator and allow H
module is not yet allowing H
is not an issue as the CPEC310 system enclosure is designed to vent excess
O span gas flow.
H
2
O span may be setup and initiated as follows.
2
O span gas source (e.g., dewpoint
2
O Span port on the CPEC310 system enclosure. Turn on
2
O span gas to flow. Even though the valve
2
O span gas to flow to the analyzer, back pressure
2
Next, navigate to the Prfrm Field H2O Span menu found under the
Attendant Zero/Span menu. Within this menu, verify the value of H2O Span
TDP matches the dewpoint setting of the H
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 7-2; specifically, it will
progress only through steps 1, 6, 7, and 8 of the steps shown in TABLE 7-2.
Progress of the H
O span may be monitored by viewing the variables Site and
2
Sec on Site. While Site reads chk H2O, monitor the real-time readings of H
in the sample cell and ensure they have reached equilibrium (i.e. are not
changing) before Site switches to set H2O. If equilibrium was not reached, the
constant TIME_ZRO_SPN needs to be increased (see Section 6.2, Set
Constants
Upon completion of the H
(p. 36)).
O span, the value of Pick SPN_H2O will return to
2
FLD_MEA, indicating that the system’s measurement mode has returned to
normal EC 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.
TABLE 7-1 includes descriptions of varaibles in the the menus related to zero
and span.
O span gas source/generator. If this
2
2
O
86
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
NOTE
NOTE
If the CPEC310 system enclosure is a long distance from the
EC155 gas analyzer (e.g., tall tower installation), it may be
necessary to increase the value of the constant TIME_ZRO_SPN
(see Section
equilibration time, especially for H
6.2, Set Constants (p. 36)) to allow for more
O. If the tubing is so long that
2
it becomes impractical to wait for equilibration, the dewpoint
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 manual setup for doing an H
O span is used, it may be
2
easier to take a laptop PC up the tower and use ECMon software
to do the H
O span. See the EC155 user manual for details on
2
doing a span using ECMon.
7.2 User-Initiated Manual Zero/Span for CPEC300 or CPEC306
Neither the CPEC300 nor the CPEC306 contains a valve module, therefore,
these systems require 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 user manual. Once plumbing connections
are prepared, the following sections may be followed to set the zero, CO
O span.
or H
2
span,
2
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 user
manual for more information on tracking the analyzer gain and
offset.
If errors in setting up and performing a zero or span lead to
nonsensical measurements or a despondent state of the analyzer,
the analyzer’s CO
and H2O coefficients may be restored to
2
previous values by navigating to Zero Span Coeffs under the
Initial Configuratn menu. Once in this menu, highlight
Reset/Change Coeffs and press Enter. To change a coefficient,
highlight it, press Enter, type the desired value, and press Enter
again to save the value. If the previous coefficient value is
unknown, enter 1.00, which will restore it to its factory settings.
After entering values, scroll to Reset Coeffs, press Enter,
highlight TRUE, and press Enter. The analyzer is now reset, and
a proper zero/span may be attempted again.
7.2.1 CPEC300/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.
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 L/min) initially to flush out the sample
87
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
cell, and then return to a low flow (< 0.5 L/min) when preparing to check
and/or set the zero.
As zero gas is flowing, watch the CO
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 CO
, H2O, and system diagnostic are displayed in the Prfrm
2
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 EC field measurements.
7.2.2 CPEC300/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. The pump is now turned off. Make sure the CO
gas tubing is connected to the Zero/Span port on the back of the EC155 gas
analyzer head and allow CO
flows (> 1 L/min) initially to flush out the sample cell, and then return to a low
flow (< 0.5 L/min) before checking and/or setting the CO
Prfrm Field CO2 Span menu verify that the variable CO2 Spn Gas matches
the concentration reported on the tank of the CO
editing, highlight it, press Enter, type in the new value, and press Enter again
to save the value. The Prfrm Field CO2 Span menu also includes readings of
molar mixing ratio. Watch the readings until they indicate that the span
CO
2
gas has flushed out the sample cell and equilibrium has been reached.
span gas to start flowing. If needed, use higher
2
and H2O readings until they indicate that
2
span
2
span. Within the
2
span gas. If this value needs
2
Once equilibrium is attained, highlight Do CO2 Span found at the bottom of
the menu, press Enter, highlight TRUE, and press Enter. 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 CO
Do CO2 Span will return to FALSE. Throughout the CO
measurements of CO
and system diagnostic are included in the Prfrm Field
2
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 EC field measurements.
7.2.3 CPEC300/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. The pump is now turned off. Make sure the H
gas tubing is connected to the Zero/Span port on the back of the EC155 gas
analyzer head and allow H
flows (> 1 L/min) initially to flush out the sample cell, and then return to a low
flow (< 0.4 L/min) before checking or setting the H
Field H2O Span menu verify that the variable H2O Span TDP is set to the
dew point temperature setting on the dew point generator or other H
gas source. If this value needs editing, highlight it, press Enter, type in the new
value, and press Enter again to save.
O span gas to start flowing. If needed, use higher
2
span, the value of
2
span, real-time
2
O span
2
O span. Within the Prfrm
2
O span
2
88
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
CAUTION
The Prfrm Field H2O Span menu includes readings of H
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. Setting the H
will take a few seconds, during which time the gas analyze measurements ma
not be updated. Upon completion of the H
to FALSE. Throughout the H
O span, real-time measurements of H2O and
2
O span, Do H2O Span will return
2
system diagnostic are included in the Prfrm Field H2O Span menu for
convenience. If the system includes a temp/RH probe, the ambient dewpoint
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 EC field measurements.
8. Maintenance and Troubleshooting
Most of the basic diagnostic and troubleshooting issues for the CPEC300-series
systems are covered in Appendix F, CPEC300 Series Diagnostics
section that follows provides additional detail on some issues that may arise
with hardware components.
8.1 Enclosure Desiccant
Check the humidity indicator card in the mesh pocket in the CPEC300-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 4-23). 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 purchase as replacements.
See Section 4.10, Replacement Parts
(p. 17), for more detail.
O molar mixing
2
O span
2
(p. F-1). The
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 CPEC300-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
plumber’s putty as described in Section 5.3.4, Apply Power
8.2 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 contaminates that are uniformly distributed on the
windows and have flat spectral characteristics than for contaminates, 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, CO
be checked for validity and windows should be cleaned during the next site
visit. Clean the windows as instructed in the EC155 CO
Gas Analyzer Manual before the CO
(p. 33).
and H2O values should
2
and H2O Closed-Path
2
and H2O signals reach 0.80.
2
89
CPEC300/306/310 Closed-Path Eddy-Covariance Systems
NOTE
In an EC155 that has the vortex intake, a decrease in signal
strength likely means that the vortex filter is plugging and should
be replaced.
8.3 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
and H2O Closed-Path Gas Analyzer Manual.
CO
2
8.4 Pump Module Filter
In very humid conditions, water may condense and collect inside the housing
of the filter that is located 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.
8.5 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:
9. Repair
• When it develops a wind offset greater than the specification
• When it sets 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 refuse 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 u
should be less than ± 8 cm∙s
± 4 cm∙s
Campbell Scientific.
All of the CPEC300-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 any repair shipments being accepted at
Campbell Scientific. See details in the Assistance section at the beginning of
this document.
, uy, and uz wind components. In this zero-wind environment, ux and uy
x
-1
(± 0.04 m∙s-1). If recalibration is deemed necessary, contact
-1
(± 0.08 m∙s-1) and uz should be less than
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.
90
Appendix A. EasyFlux DL CR6CP Process Flow
Sequence of Program Functions
Every SCAN_INTERVAL (default 100 ms)
Collect raw data from GPS sensor, battery voltage, CDM panel temp,
FW, and rain gauge
⇩
Store FW measurements in a table to be used later to align with sonic
data
⇩
Check for conditions that require EC100 reconfiguration
⇩
Store previous scan’s sonic and gas data 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 (i.e., call site_block_mean table)
⇩
Check to see if the mode of operation has changed. If yes, perform
functions associated with that mode (e.g., zero and span) and when
finished, return to EC field measurements.
⇩
Record the prior scan’s time series data into final storage
⇩
Parse out sonic diagnostic data, and filter bad sonic data from being
included in statistical data
⇩
A-1
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