Open-Path Eddy-Covariance System Operator’s Manual IRGASON, KH20, and FW05 Revision: 4/13 C o p y r i g h t © 2 0 0 4 - 2 0 1 3 C a m p b e l l S c i e n t i f i c , I n c .
Warranty “PRODUCTS MANUFACTURED BY CAMPBELL SCIENTIFIC, INC. are warranted by Campbell Scientific, Inc. (“Campbell”) to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless otherwise specified in the corresponding Campbell pricelist or product manual. Products not manufactured, but that are re-sold by Campbell, are warranted only to the limits extended by the original manufacturer.
Assistance Products may not be returned without prior authorization. The following contact information is for US and international customers residing in countries 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. To obtain a Returned Materials Authorization (RMA), contact CAMPBELL SCIENTIFIC, INC., phone (435) 227-9000.
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. System Description ....................................................1 1.1 1.2 1.3 1.4 OPEC (CSAT3 Only)...........................................................................1 Basic OPEC..........................................................................................1 Extended OPEC ..............................................
Table of Contents Appendices A. CSAT3 Orientation ..................................................A-1 A.1 A.2 Determining True North and Sensor Orientation ............................ A-1 Online Magnetic Declination Calculator ......................................... A-3 B. References...............................................................B-1 C. OPEC200 Open Path Eddy Covariance System Quickstart Guide...................................................C-1 Figures 2-1. 3-1. 3-2. 4-1. 4-2. 4-3.
Table of Contents Tables 2-1. 2-2. 2-3. Nominal Sensor Power Requirements..................................................5 Nominal Datalogger Power Requirements with the Display Off and No RS-232 Communications .....................................................5 Nominal Datalogger Power Requirements with the Display and Backlight On, and No RS-232 Communications..............................
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OPEC Open-Path Eddy-Covariance System This document will serve as a guide to properly install and operate a Campbell Scientific Open-Path Eddy-Covariance System (OPEC). The OPEC is composed of various products, e.g., dataloggers, fast response turbulence sensors, slow response meteorological sensors, and software. These products are manufactured by Campbell Scientific and other vendors. Manuals for each of these sensors shipped with the system. It is time well spent reviewing these documents.
OPEC Open-Path Eddy-Covariance System 1.3 Extended OPEC Energy balance sensors can be added to a basic OPEC system to also measure the net radiation, soil heat flux, soil temperature, and soil water content. The sensors required for these additional measurements are a NR-LITE, CNR2, NR01 or CNR4 net radiometer; two or four HFP01 or HFP01-SC soil heat flux plates, one or two TCAV averaging soil temperature probes, and one or two CS616 or CS650 soil moisture reflectometers.
OPEC Open-Path Eddy-Covariance System TIP Keep a log book for each station. Record the date and personnel name for all site visits, as well as all maintenance and work that is performed during the site visit. Document the condition of the sensors and site with a digital camera. FIGURE 2-1.
OPEC Open-Path Eddy-Covariance System 2.1 Fetch and Sensor Height The eddy-covariance sensors must be mounted at some height to ensure that the measurements are made within the local surface layer. The local surface layer grows at a rate of approximately 1 vertical meter per 100 horizontal meters. Thus, a height to fetch (horizontal distance travelled) ratio of 1:100 may be used as an absolute bare minimum rough rule of thumb for determining the measurement height.
OPEC Open-Path Eddy-Covariance System TABLE 2-1. Nominal Sensor Power Requirements Sensor IRGASON IRGASON (gas head powered down) KH20 HMP45C Power (mW) 400 mA @ 12.5 Vdc 240 mA @ 12.5 Vdc 10 - 20 mA @ 12.5 Vdc <3.8 mA @ 12.5 Vdc TABLE 2-2. Nominal Datalogger Power Requirements with the Display Off and No RS-232 Communications Datalogger CR1000 w/ CFM100 & CF card CR3000 w/ CFM100 & CF card CR5000 w/ PC/CF card Power (mW) 8 mA @ 12.5 Vdc 39 mA @ 12.5 Vdc 63 mA @ 12.5 Vdc TABLE 2-3.
OPEC Open-Path Eddy-Covariance System as a line item on the order, contact Campbell Scientific to purchase the appropriate datalogger program for your open-path eddy-covariance system. The program covers a variety of sensors and is continuously growing. If your system uses sensors that are not currently supported by the program, add the appropriate measurement and processing instructions to the program or contact Campbell Scientific for assistance.
OPEC Open-Path Eddy-Covariance System To enter the “sonic_azimuth” using the datalogger keyboard, press the key until the Campbell Scientific Inc. logo is visible in the upper left hand corner of the display. Press the key. Select the menu “Sonic_Azmth” and press the key. Enter the azimuth of the negative x-axis and press the key. Press the several times so that the Campbell Scientific logo if visible.
OPEC Open-Path Eddy-Covariance System North Wind Vane Wind Vector X Y FIGURE 3-2. Compass coordinate system, compass wind direction is 140 degrees 3.1.2 Sensor Configuration The IRGASON communicates with Campbell Scientific dataloggers using a digital communication protocol called Synchronous Device for Measurement (SDM). Each sensor connected to the SDM bus has a unique address. A maximum of 15 addresses are allowed by the protocol and each sensor must have a unique SDM address.
OPEC Open-Path Eddy-Covariance System CAUTION 3.2 If you loan an IRGASON to a colleague, verify that the address is 1 before deploying the system into the field. Loading a Program to the Datalogger Before the datalogger can begin to make measurements, a program must be transferred into its CPU. The program can be transferred using a PC and LoggerNet or using PC/CF cards. 3.2.
OPEC Open-Path Eddy-Covariance System key, select “CRD:” and again press the key. The datalogger will now display a list of program files on the card. Navigate to the eddy-covariance program and press the key. The cursor will jump to the “To” line. Press the key and then the right arrow, select CPU:filename. Press the key and down arrow. Finally, press the key to execute the copy from the card to the CPU.
OPEC Open-Path Eddy-Covariance System CompileResults: Reports compile errors. VarOutOfBound: An element of an array was referenced that does not exist, e.g., a VarOutOfBound is reported if element wind(9) is referenced in the program, but the array was defined with 5 elements. SkippedScan: If the maximum number of buffered scans is exceeded (defined in the third parameter of the Scan () instruction), the Processing and Measurement tasks are resynchronized.
OPEC Open-Path Eddy-Covariance System seconds and nanoseconds since 0000 hrs, 1 Jan 1990. In the TOA5 format, the time stamp is a quoted string, similar to that used in Microsoft® Excel. In the Array Compatible CSV, time is reported as elements of the array, e.g., in the same format as the Campbell Scientific mixed array dataloggers. NOTE Campbell Scientific recommends the use of TOB1 file format. This file format can be readily read into third party post processing software, e.g., EdiRe or MatLab.
OPEC Open-Path Eddy-Covariance System 4.1.1 Direct Connection Data Retrieval via LoggerNet LoggerNet can be used to automatically collect and organize data from an Open-Path Eddy-Covariance system. This approach is some what limited because of the slow throughput into the PC’s RS-232 port. For all practical purposes, the PC must remain continuously connected to the datalogger. It will take about 8% to 25% of real time to collect 10 Hz time series data, e.g.
OPEC Open-Path Eddy-Covariance System FIGURE 4-2. LoggerNet station setup for the “ts_data” table In the “Schedule” tab, configure the station’s data collection as shown in FIGURE 4-3. Modify the Primary Retry Interval, Number of Primary Retries, and the Secondary Retry interval as needed for the specific telecommunications option used at the station.
OPEC Open-Path Eddy-Covariance System To enable LoggerNet’s data collection, click on the Status Monitor button in the Toolbar. Select the station and click on the “Toggle On/Off” button. The time of the next data collection will appear in the “Next Data Call” column (see FIGURE 4-4). To display additional station information, right click on any column header and then Select “Column…”. For more information, see Section 6.1 Status in the LoggerNet manual. FIGURE 4-4. LoggerNet station status monitor 4.1.
OPEC Open-Path Eddy-Covariance System FIGURE 4-5. Baler station setup for the “flux” table FIGURE 4-6.
OPEC Open-Path Eddy-Covariance System 4.1.3 Remote Data Retrieval via a PC/CF Card To transfer data manually from the PC/CF card to the PC, remove the card from the datalogger following the proper card removal procedure (see the appropriate datalogger manual for details). Insert a fresh card into the datalogger or copy the data from the card to a working directory on the computer. Transferring data using the PC/CF card is relatively fast.
OPEC Open-Path Eddy-Covariance System 4.1.4 File Management with CardConvert CardConvert is a utility that is shipped with LoggerNet and is used to convert the files on a card from the compact file format TOB3 to a TOB1, TOA5, or Array Compatible CSV (see FIGURE 4-7). This utility is installed on the PC under the Start menu in the Programs | Campbell Scientific | LoggerNet | Utilities group. To take advantage of all the functionality described in this section, use CardConvert version 1.2 or later.
OPEC Open-Path Eddy-Covariance System Start the CardConvert utility. When CardConvert is started, a summary of its current settings is displayed in the lower right hand screen. There are four screens/parameters to setup and configure in CardConvert. Once configured, CardConvert will save these settings in the Windows Registry. In subsequent runs, only the default Output File name must be changed.
OPEC Open-Path Eddy-Covariance System • TIP Practice converting the data from the card and processing it with your off-line tools. Only through this type of experimentation will you determine the file sizes that work best for you. • NOTE Set the file size (Bale size) in the “Time Settings” screen. For the time series files, use a one hour file size and for the online flux data, use a one day file size. Finally, change the output file name. The default output file name is TOB1_stationname.ts_data.
OPEC Open-Path Eddy-Covariance System FIGURE 4-10. List of files created by CardConvert 4.1.4.1 Collecting Data with One Card If a single card is used to collect the data and the data on the card is not deleted after copying it to the PC, the datalogger will append the data collected since the card was removed to the data file on the card. This means that the next time data is collected and converted from the PC/CF card, the last file in FIGURE 4-10 will contain a complete hour of data.
OPEC Open-Path Eddy-Covariance System FIGURE 4-11. List of files created by CardConvert with duplicates FIGURE 4-12. List of files where the duplicate files are renamed to *.bak 4.1.4.2 Collecting Data with Two Cards Data can be collected using two cards. The card in the datalogger is removed and replaced with an empty one. The data from the original card is copied to the computer at some later time.
OPEC Open-Path Eddy-Covariance System NOTE Using two or more cards is a fast and efficient method of collecting data. Only new data is collected; however, two partial files within a “baling” period are created. Variable file lengths are not an issue with EdiRe. Again, note that the first and last files (FIGURE 4-13) are smaller than the rest of the files. The next time data is retrieved from the datalogger, the file Ts_data_2000_02_25_0700.dat will be continued in another file (FIGURE 4-14). FIGURE 4-13.
OPEC Open-Path Eddy-Covariance System 4.2 Data Processing There are several ways to process the raw time series data collected by the system. Some of these are considered standard by the community and others are subject to much debate. To gain a better understanding of the issues, review the literature. 4.2.1 Online Processing The Open-Path Eddy-Covariance datalogger programs perform the processing listed below online and in real time. In many cases, no further processing of the data is required.
OPEC Open-Path Eddy-Covariance System • Spatial separation correction or maximum covariance. • Coordinate rotation (mean vertical wind = 0 or planar fit). • Spectral analysis. • Wavelet analysis. • Webb et al. (1980) term for latent heat flux and CO2 flux. This term is separated into its components due to temperature and to vapor density fluctuations. • Wind direction and wind speed from the sonic anemometer. • KH20 Krypton Hygrometer oxygen correction.
OPEC Open-Path Eddy-Covariance System FIGURE 4-15. Interpreter settings to read a Campbell Scientific TOB1 data file FIGURE 4-16.
OPEC Open-Path Eddy-Covariance System FIGURE 4-17. Completed Interpreter screen FIGURE 4-18. Estimated sample frequency and correct sample frequency 4.2.2.2 Example EdiRe Raw File Format and Processing Lists To view the Lists in EdiRe, select the Processing | Options menu. The “Raw File Format” list. The default “Processing Steps” list must be modified for your specific application.
OPEC Open-Path Eddy-Covariance System The Processing Steps list has the default instructions needed to extract the data from the TOB1 file (FIGURE 4-19). Additional instructions can be found in the “Processing Items” list. To configure the instruction, select the instruction parameter and enter values either from the “Processing Item Parameter” pull down menu, or enter output variable names in the “Processing Item Parameter” field using the keyboard.
OPEC Open-Path Eddy-Covariance System FIGURE 4-20. Output file location as part of the processing list FIGURE 4-21.
OPEC Open-Path Eddy-Covariance System FIGURE 4-22. Processing Uz and CO2 with 1 Chn Statistics instruction FIGURE 4-23.
OPEC Open-Path Eddy-Covariance System 5. Basic Eddy-Covariance Theory Appendix B lists several references on eddy-covariance flux measurements.
OPEC Open-Path Eddy-Covariance System The surface layer (FIGURE 5-1) is comprised of approximately the lower 10% of the atmospheric boundary layer (ABL). The fluxes of water vapor and heat within this layer are nearly constant with height when the following criteria are met: the surface has approximate horizontal homogeneity; and the relationship z/h << 1 << z/zom is true, where zsfc is the height of the surface layer, h is the height of the ABL, and zom is the roughness length of momentum.
Appendix A. CSAT3 Orientation A.1 Determining True North and Sensor Orientation The orientation of the CSAT3 negative x-axis is found by reading a magnetic compass and applying the site-specific correction for magnetic declination; where the magnetic declination is the number of degrees between True North and Magnetic North. Magnetic declination for a specific site can be obtained from a USGS map, local airport, or through a NOAA web calculator (Section A.2).
Appendix A. CSAT3 Orientation Declination angles are always subtracted from the compass reading to find True North. A declination angle East of True North is reported as positive a value and is subtracted from 360 (0) degrees to find True North as shown FIGURE A-2. A declination angle West of True North is reported as a negative value and is also subtracted from 0 (360) degrees to find True North as shown in FIGURE A-3.
Appendix A. CSAT3 Orientation A.2 Online Magnetic Declination Calculator The magnetic declination calculator web calculator published by NOAA’s Geophysical Data Center is available at the following url http://www.ngdc.noaa.gov/seg/geomag/jsp/struts/calcDeclination. After the web page loads, enter the site zip code, or longitude and latitude, then click on the “Compute Declination” button (FIGURE A-4). FIGURE A-4.
Appendix A.
Appendix B. References Abuinet, M., Vesala, T., and Papale, D. (eds), 2012: Eddy Covariance, A Practical Guide to Measurement and Data Analysis, Springer, New York, 438 pp. Brutsaert, W.: 1982, Evaporation into the Atmosphere, D. Reidel Publishing Co., Dordrecht, Holland, 300. Buck, A. L.: 1976, “The Variable-Path Lyman-Alpha Hygrometer and its Operating Characteristics”, Bull. Amer. Meteorol. Soc., 57, 1113-1118. Burba, G. G., and Anderson, D. J.
Appendix B. References Schotanus, P., F. T. M. Nieuwstadt, and H. A. R. de Bruin, 1983: Temperature measurement with a sonic anemometer and its application to heat and moisture fluxes, Bound.-Layer Meteorol., 26, 81-93. Schuepp, P. H., Leclerc, M. Y., MacPherson, J. I., and Desjardins, R. L.: 1990, “Footprint Prediction of Scalar Fluxes from Analytical Solutions of the Diffusion Equation”, Bound.-Layer Meteorol., 50, 355-373. Shuttleworth, W. J.
Appendix C. OPEC200 Open Path Eddy Covariance System Quickstart Guide 1. Setup tripod and mount enclosures.
Appendix C. OPEC200 Open Path Eddy Covariance System Quickstart Guide 2. Ground tripod and enclosures.
Appendix C. OPEC200 Open Path Eddy Covariance System Quickstart Guide 3. Setup tripod or mast with CM20X Crossarm.
Appendix C. OPEC200 Open Path Eddy Covariance System Quickstart Guide 4. Mount the IRGASON into the prevailing wind.
Appendix C. OPEC200 Open Path Eddy Covariance System Quickstart Guide 5. Mount the radiation shield and IRGASON Temperature Probe.
Appendix C. OPEC200 Open Path Eddy Covariance System Quickstart Guide 6. Connect gas analyzer, sonic anemometer, and temperature probe cables to EC100 Electronics.
Appendix C. OPEC200 Open Path Eddy Covariance System Quickstart Guide 7. Connect system wiring and insert compact flash (CF) card.
Appendix C. OPEC200 Open Path Eddy Covariance System Quickstart Guide 8. Turn on the power supply and use the datalogger keyboard display to set settings. (Follow the steps from left to right, top to bottom). Press to activate the display. Press to display the System Control Menu. Campbell Scientific Select “Sonic Azmth”. CR3000 Datalogger 01/01/2012, 14:00:08.4 CPU: OPEC_basic_vx_x.cr3 Running. System Control Sonic Azmth :0.
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