BOREAS TGB-01/TGB-03 NEE Data over the NSA Fen Summary The BOREAS TGB-01 and TGB-03 teams collected several data sets that contributed to understanding the measured trace gas fluxes over sites in the NSA. This data set contains NEE measurements collected with chambers at the NSA fen in 1994 and 1996. Gas samples were extracted approximately every 7 days from chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files. Table of Contents * 1 Data Set Overview * 2 Investigator(s) * 3 Theory of Measurements * 4 Equipment * 5 Data Acquisition Methods * 6 Observations * 7 Data Description * 8 Data Organization * 9 Data Manipulations * 10 Errors * 11 Notes * 12 Application of the Data Set * 13 Future Modifications and Plans * 14 Software * 15 Data Access * 16 Output Products and Availability * 17 References * 18 Glossary of Terms * 19 List of Acronyms * 20 Document Information 1. Data Set Overview 1.1 Data Set Identification BOREAS TGB-01/TGB-03 NEE Data over the NSA Fen 1.2 Data Set Introduction Trace Gas Biogeochemistry Teams 1 and 3 (TGB-03) took net ecosystem exchange of C02 (NEE) measurements at the Northern Study Area (NSA) fen site using chambers from early June to September 1994 and from April to late October 1996 for the BOReal Ecosystem -Atmosphere Study (BOREAS). Chamber NEE measurements were taken at the four subsites within the fen in the NSA to determine the NEE rates at these locations. The locations represent the range of plant communities, water chemistry, and peatland types found in northern peatlands, including bog, rich fen, poor fen, and collapse scar (pH ranges from 3.8 to 7.2). Continuous measurements of water level and air and soil temperatures were taken to understand the thermal and hydrological gradients associated with each plant community. Measurements were made from the period of snow melt and thaw through the full growing season to fall freeze up to examine the seasonal patterns of NEE, differences in phenology, and relative importance of vascular plants and bryophytes to the carbon balance. The following is a description of the acquisition of data and the final data sets. 1.3 Objective/Purpose The purpose of these measurements was to examine the range and magnitude of NEE between the atmosphere and the wetland plants and soils. Continuous measurements of water level and air and soil temperature measurements were also made to understand the environmental controls on NEE. Plant species composition within the NEE collars was measured to understand the differences in NEE among the various plant communities in the fen. 1.4 Summary of Parameters NEE, air and water temperatures, and water levels were measured in the NSA fen. In addition, the plant communities for each chamber were characterized. 1.5 Discussion NEE was measured at four subsites in the NSA fen, designated as collapse bog (CB), collapse fen (CF), tower fen (TF), and Zoltai fen (ZF). Each collar location is further designated by a spur (1, 2, 3, or 4) along the boardwalk at each subsite and by the microtopography or dominant ground cover of the collar location: pal=palsa, hk=hummock, hw=hollow, lwn=lawn, moat=open water at the edge of the collapse scars, b_moss=brown moss, sph=sphagnum, and lich=lichen. NEE, dark CO2 flux (respiration), and photosynthesis (derived from the difference between NEE and respiration), photosynthetically active radiation (PAR) are the parameters for the NEE data files. Continuous water table and temperatures were recorded at each of the subsites to accompany the NEE measurements. Temperatures of the air, 5-cm, 10-cm, 20-cm, and 50-cm peat depth were measured at each subsite. Temperatures correspond to the collar location at the subsite. In cases where the continuous data were missing, manual soil temperatures were recorded. Continuous water level measurements were taken at each subsite and are designated by the subsite abbreviation and the number of the spur (e.g., CBWL1=collapse bog, water level, spur 1). Plant species composition of each NEE collar was recorded as percent cover of the total collar area. The NEE data are included in four American Standard Code for Information Interchange (ASCII) (DOS)-delimited text files, one for each subsite: CB96_NEE.txt, CF96_NEE.txt, TF96_NEE.txt, and ZF96_NEE.txt. The parameters are NEE, PAR, respiration, and photosynthesis. The water table and temperature measurements are located in four ASCII (DOS)-delimited text files, one for each subsite: CB96_WT1.txt, CF96_WT1.txt, TF96_WT1.txt, and ZF96_WT1.txt. The plant data for the collars at all four subsites are located in one ASCII (DOS)- delimited text file: fen96_pla.txt. 1.6 Related Data Sets BOREAS TGB-01 CH4 Tower Flux Data over the NSA BOREAS TGB-01/TGB-03 Water Table and Peat Temperature Data over the NSA BOREAS TGB-03 CH4 Chamber Flux Data over the NSA Fen BOREAS TGB-03 Plant Species Composition Data over the NSA Fen 2. Investigator(s) 2.1 Investigator(s) Name and Title Dr. Jill L. Bubier Research Associate University of New Hampshire Dr. Patrick M. Crill Research Associate Professor University of New Hampshire Dr. Tim R. Moore Professor McGill University 2.2 Title of Investigation Magnitude and Control of Trace Gas Exchange in Boreal Ecosystems 2.3 Contact Information Contact 1 --------- Dr. Jill L. Bubier Institute for the Study of Earth, Oceans, and Space Complex Systems Research Center University of New Hampshire Durham, NH (603) 862-4208 (603) 862-0188 (fax) jill.bubier@unh.edu Contact 2 --------- Dr. Patrick M. Crill Institute for the Study of Earth, Oceans, and Space Complex Systems Research Center University of New Hampshire Durham, NH (603) 862-3519 (603) 862-0188 (fax) patrick.crill@unh.edu Contact 3 --------- Ruth K. Varner Research Scientist Institute for the Study of Earth, Oceans, and Space Complex Systems Research Center University of New Hampshire Durham, NH (603) 862-2939 (603) 862-0188 ruth.kerwin@unh.edu Contact 4 --------- Dr. Tim R. Moore Geography Department McGill University Montreal, Quebec Canada (514) 398-4961 (514) 398-7437 (fax) moore@felix.geog.mcgill.ca 3. Theory of Measurements Chamber fluxes measure the changes in mixing ratio of trace gases (CO2) in a closed headspace over a period of time. This headspace is isolated from the atmosphere; therefore, the exchange of material between the covered soil and the headspace can be quantified. 4. Equipment 4.1 Sensor/Instrument Description NEE was quantified with a LI-COR (LI-COR, Inc., Lincoln, Nebraska) portable photosynthesis system (LI-6200), which includes the LI-6250 infrared gas analyzer (IRGA), system console with 256K memory, 9960-035 Sensor Housing, 6000TC leaf temperature thermocouples, a Vaisala HUMICAP humidity sensor, quantum sensor for PAR measurements, field stand, 6000B rechargeable battery packs, 6200B rechargeable battery packs, LI-6020 battery charger, 6200DP desiccant tubes for magnesium perchlorate, 1000-90 communications software, 6200-25 support software, and RS-232C output leads for Data Terminal Equipment (DTE) and Data Communication Equipment (DCE). A wood frame backpack for carrying the LI-6200 and ancillary equipment to the field sites was designed and manufactured by George Stone at Arundo Woodworking, Hyde Park, Vermont. The portable climate-controlled chambers were designed by Patrick Crill, Paul Carroll, and Ruth Kerwin and were modeled after a chamber described in Whiting et al., J. Geophys. Res. 96: 13,067-13,071, 1991. The chambers were manufactured at University of New Hampshire (UNH) by Ruth Kerwin and were constructed of clear Lexan and Teflon film to allow maximum light penetration. One of two chamber sizes of chambers was used depending on the height of the vegetation. The larger chamber covered 3660 cm2 of surface area and was 90.5 cm in height. The aluminum frame was covered on three sides with 5-mil Teflon film. The fourth side was constructed of a rigid polycarbonate wall (1/8” Lexan) on which the climate control and sampling equipment were mounted. The chamber top was made of 1/8” Lexan and was removable to allow equilibration of plant communities to ambient conditions between sampling runs. The climate control system consisted of a small heat exchanger (radiator) and a cooler for pumping cold water. The cooler was filled with water, ice, and a battery-powered pump and attached to the chamber with hoses to circulate the cold water to the heat exchanger. Three small brushless fans circulated the air across the radiator, cooling the enclosed air to within 1o C of ambient air temperature outside the chamber. The smaller chamber covered the same area as the larger chamber to fit the same collars (3660 cm2), but was half the height (45 cm). All four sides and top of the smaller chamber were constructed of 1/8” Lexan. In order to measure NEE at different light levels, shrouds of different mesh size were used to reduce the light entering the chamber to 1/2, 1/4, and 0 full light. The aluminum collars were designed by Patrick Crill and manufactured at UNH. The collars were inserted into the peat in the fall of 1995 to minimize disturbance during the sampling period beginning in the spring of 1996. Continuous water table measurements were made with a float and counter weight attached to a wheel and potentiometer mounted on a platform that rested on top of a wooden post anchored in the clay below the peat. The potentiometer, which was wired to either a CR10 or CR7 data logger (Campbell Scientific, Inc., Logan, Utah), recorded the change in water level in mV. Wells were constructed of PVC tubing. Peat temperatures were recorded with type T thermocouples (copper- constantan) attached at four levels (5, 10, 20 and 50 cm) to wooden stakes and inserted into the peat during the fall of 1995. The thermocouples were wired to either CR10 or CR7 dataloggers and calibrated to reference temperatures. 4.1.1 Collection Environment The chamber fluxes were collected under all environmental conditions. The calibrations and data analyses were completed at the Heritage North Museum laboratory in Thompson, Manitoba. 4.1.2 Source/Platform Ground. 4.1.3 Source/Platform Mission Objectives The objective was to determine the plant-soil-surface exchange rates of CO2 at the NSA fen complex. 4.1.4 Key Variables The key variables measured during the sampling period were NEE, PAR, air temperature, peat temperature at four peat depths, water table position, and plant species composition. 4.1.5 Principles of Operation The LI-6200 portable photosynthesis system consists of a LI-6250 CO2 IRGA, sensor head, and datalogger. The LI-6250 consists of an IRGA, a mass flow meter, and a pump. It can be configured for either absolute or differential modes of operation by rearranging the external plumbing. The analyzer was used in absolute mode. The CO2 measurement is based on the difference in intensity of infrared radiation passing through two gas sampling tubes: a reference tube contains a known amount of CO2, and a sample tube contains an unknown amount. Infrared radiation is transmitted through both paths, and the output of the analyzer is proportional to the difference in absorption between the two. The lead selenide detector is cooled and regulated to -12° C by a thermoelectric cooler. To keep the detector housing free of water vapor and CO2, a small bottle of magnesium perchlorate and soda lime is attached to the detector (LI- COR, Inc.). 4.1.6 Sensor/Instrument Measurement Geometry Not applicable. 4.1.7 Manufacturer of Sensor/Instrument Manufacturer of LI-6200 portable photosynthesis system: LI-COR, Inc. Box 4425 4421 Superior St. Lincoln, NR 68504 USA (402) 467-3576 (402) 467-2819 (fax) Manufacturer of CR10 and CR7 dataloggers: Campbell Scientific, Inc. 815 W. 1800 N. Logan, UT 84321-1784 USA (801) 753-2342 (801) 750-9540 (fax) 4.2 Calibration 4.2.1 Specifications The IRGA was calibrated against Canadian Atmospheric Environment Services (AES) certified primary CO2 standards acquired by the BOREAS project. Calibration in absolute mode was accomplished by flowing 0-ppm CO2 through the analyzer (scrubbing of CO2 with soda lime) and adjusting the zero potentiometer until the displayed reading was 0 ppm. Then the span was checked by flowing a known concentration of CO2 through the analyzer and adjusting the span potentiometer until the displayed reading was correct. An AES standard of 397.3 ppm CO2 was used for the span calibration. The analyzer was usually within 1-2 ppm of the known concentration. The zero and span were checked twice during each calibration. 4.2.1.1 Tolerance None given. 4.2.2 Frequency of Calibration The CO2 analyzer was calibrated on a daily basis, every morning in the Heritage North Museum lab before going to the field sites. The zero was rechecked and calibrated several times during the day because it was sensitive to changes in air temperature. 4.2.3 Other Calibration Information Not applicable. 5. Data Acquisition Methods NEE was calculated using the change in concentration of CO2 in the chamber headspace over a 2.5-minute sampling period. The IRGA sampled every 5 seconds and averaged the flux rate every 30 seconds. The CO2 flux for each sampling run was calculated as a mean of the five 30-second sampling intervals during the 2.5-minute period. The total sampling period was kept very short to minimize the time the plants were exposed to the chamber environment. Temperature and relative humidity inside the chamber were monitored closely during each run to make sure that conditions did not change significantly during the sampling period. For every collar, separate sampling runs were conducted under full light, 1/2 light, 1/4 light, and dark conditions. Less than full light measurements were obtained by placing shrouds of different mesh sizes over the chamber. Grab samples of air for measuring CH4 flux were taken during each dark run (see documentation file CH4doc.doc for BOREAS TGB-01). Temperature and water level were measured continuously and averaged every hour on the CR10 or CR7 dataloggers. Manual measurements of air temperature, peat temperature, and water table position were made at the same time as the NEE measurements. Plant species composition was recorded in each collar during the height of the growing season in mid-July 1996. Visual estimates of percent cover of each vascular plant and bryophyte species were made based on light interception of the canopy of each species. Percent cover of all species totals over 100 percent for each collar because of several layers of vegetation. Specimens for each unknown species were collected in plant communities outside of the collars and identified in the lab at the Heritage North Museum, Thompson, Manitoba, or at Dr. Barry Rock's laboratory at Complex Systems Research Center, UNH, Durham, NH. 6. Observations 6.1 Data Notes None given. 6.2 Field Notes None given. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage CB collars were located in a small, circular collapse scar (75 m diameter) almost completely surrounded by a permafrost peat plateau, behind the generator shed. Three spurs were located perpendicular to the boardwalk. Spur 1 was adjacent to the moat, or open water lagg area; spur 2 was in a hummock-hollow area; and spur 3 was in the center of the collapse scar. In addition to the collars in the collapse scar, this subsite had two collars on the palsa (frozen peat plateau) adjacent to the collapse scar. Collar designations were as follows: CB1moat = collapse bog, spur 1, moat CB2hk = collapse bog, spur 2, hummock CB2hw = collapse bog, spur 2, hollow CB3hk = collapse bog, spur 3, hummock CBpalmoss = collapse bog, palsa, moss Cbpallich = collapse bog, palsa, lichen CF collars were located in a small, linear collapse feature that was east of and accessed from the main trail to the tower hut. Four spurs were located perpendicular to the main boardwalk. Spur 1 was located adjacent to the moat spur 2 was in a uniform lawn of Sphagnum riparium spur 3 was in a small treed ridge and spur 4 was on the far edge of the collapse scar where the influence of groundwater was apparent. Collar designations were as follows: CF1moat = collapse fen, spur 1, moat CF2lwn = collapse fen, spur 2, lawn CF3hka = collapse fen, spur 3, hummock (a) CF3hkb = collapse fen, spur 3, hummock (b) CF4b_moss = collapse fen, spur 4, brown moss CF4sph = collapse fen, spur 4, sphagnum TF collars were located along the boardwalk to the micrometeorological tower in the NSA fen. Four spurs were located perpendicular to the main boardwalk. Spur 1 was just beyond the moat at the beginning of the boardwalk in a treed area of tamarack (Larix laricina) spur 2 was in a tall shrub zone (Betula glandulosa), spur 3 was in a low shrub zone just before the hut and spur 4 was just beyond the hut in a mixed low shrub/sedge zone. Collar designations were as follows: TF1hk = tower fen, spur 1, hummock TF2hk = tower fen, spur 2, hummock TF2hw = tower fen, spur 2, hollow TF3hk = tower fen, spur 3, hummock TF3hw = tower fen, spur 3, hollow TF4hw = tower fen, spur 4, hollow ZF collars were located in a sedge-dominated (Carex spp.) fen area of the peatland complex, north of the fen tower, and accessed from Route 391. Three spurs were located perpendicular to the main boardwalk. Spur 1 was on a treed ridge; spur 2 was in a shrub-dominated hummock-hollow area; and spur 3 was in a wet, sedge-dominated area near the edge of a palsa. Collar designations were as follows: ZF1hk = zoltai fen, spur 1, hummock ZF2hk = zoltai fen, spur 2, hummock ZF2hw = zoltai fen, spur 2, hollow ZF3b_moss = zoltai fen, spur 3, brown moss ZF3hw = zoltai fen, spur 3, hollow (Sphagnum) ZF3hk = zoltai fen, spur 3, hummock (Sphagnum) 1994 NEE data from Lianne Bellisario: CB1cL1 = collapsed bog, spur 1, carpet, collar 1 CB1cL2 = collapsed bog, spur 1, carpet, collar 2 CB1cL3 = collapsed bog, spur 1, carpet, collar 3 CB1cL4 = collapsed bog, spur 1, carpet, collar 4 CB1cL5 = collapsed bog, spur 1, carpet, collar 5 CF1cL1 = collapse fen, spur 1, carpet, collar 1 CF1cL2 = collapse fen, spur 1, carpet, collar 2 CF1cL3 = collapse fen, spur 1, carpet, collar 3 CF1cL4 = collapse fen, spur 1, carpet, collar 4 CF1cL5 = collapse fen, spur 1, carpet, collar 5 CF2nL1 = collapse fen, spur 2, lawn, collar 1 CF2nL2 = collapse fen, spur 2, lawn, collar 2 CF2nL3 = collapse fen, spur 2, lawn, collar 3 CF2nL4 = collapse fen, spur 2, lawn, collar 4 CF2nL5 = collapse fen, spur 2, lawn, collar 5 TF4wL1 = tower fen, spur 4, hollow, collar 1 TF4cL2 = tower fen, spur 4, carpet, collar 2 TF4cL3 = tower fen, spur 4, carpet, collar 3 TF4kL4 = tower fen, spur 4, carpet, collar 4 ZF3cL1 = zoltai fen, spur 3, carpet, collar 1 ZF3cL2 = zoltai fen, spur 3, carpet, collar 2 ZF3cL3 = zoltai fen, spur 3, carpet, collar 3 ZF3pL4 = zoltai fen, spur 3, pool, collar 4 ZF3pL5 = zoltai fen, spur 3, pool, collar 5 7.1.2 Spatial Coverage Map None given. 7.1.3 Spatial Resolution The 24 collars spanned the full range of hydrologic, plant community, and water chemistry gradients found in the larger peatland complex. They were placed along those gradients at each of the four subsites to capture the spatial variability in CO2 fluxes. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage The chamber NEE measurements were made from 06-June-1994 to 02-September 1994 and 15-April-1996 to 23-October-1996. Associated water table and temperature measurements were recorded as well but are provided in a separate data set. 7.2.2 Temporal Coverage Map Not applicable. 7.2.3 Temporal Resolution The chamber NEE measurements for 15 of the collars were made approximately every 7 days. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (tgbfenne.def) 7.4 Sample Data Record Sample data format shown in the companion data definition file (tgbfenne.def) 8. Data Organization 8.1 Data Granularity All of the TGB-01/TGB-03 NEE Data over the NSA Fen are contained in one dataset. 8.2 Data Format(s) The data file contains numerical and character fields of varying length separated by commas. The character fields are enclosed with single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition file (tgbfenne.def) 9. Data Manipulations 9.1 Formulae None. 9.1.1 Derivation Techniques and Algorithms Not applicable. 9.2 Data Processing Sequence 9.2.1 Processing Steps CO2 (NEE) data were downloaded from the LI-6200 datalogger to laptop computers in the Heritage North Museum lab every day after returning from the field. The data were entered into spreadsheets, and the average flux for the 2.5-minute runs were calculated. Ancillary data that were recorded during the runs and included on the data sheets were number of sample runs, time interval for calculating flux rate, temperature of the chamber, relative humidity, and chamber volume. Data on leaf measurements, stomatal conductance, stomatal resistance, etc., were not relevant to this study. Temperature and water table data from the CR10 and CR7 dataloggers were downloaded every 3-4 days and entered into the spreadsheets at the lab. 9.2.2 Processing Changes Not applicable. 9.3 Calculations If -888 is present in the data set, it indicates that a measurement was taken, but was discarded for some reason. If -999 is present, then no data were taken. 9.3.1 Special Corrections/Adjustments Not applicable. 9.3.2 Calculated Variables Not applicable. 9.4 Graphs and Plots None given. 10. Errors 10.1 Sources of Error Placing the chamber down with much force can change the pressure inside the chamber to other than ambient and can affect the mechanisms and processes producing/taking up CO2. (Errors such as this would have been written down in the lab/field books and these data therefore would have been edited out.) 10.2 Quality Assessment 10.2.1 Data Validation by Source None given. 10.2.2 Confidence Level/Accuracy Judgment Not applicable. 10.2.3 Measurement Error for Parameters None given. 10.2.4 Additional Quality Assessments Not applicable. 10.2.5 Data Verification by Data Center Data were examined for general consistency and clarity. 11. Notes 11.1 Limitations of the Data None given. 11.2 Known Problems with the Data None given. 11.3 Usage Guidance Not applicable. 11.4 Other Relevant Information Not applicable. 12. Application of the Data Set The chamber flux data can be used in connection with the tower flux data to determine the CO2 exchange between the atmosphere and the peatland soils. The remote sensing images, the chamber plant community data, and the chamber NEE data, can be used to scale the CO2 fluxes from the plot scale to wetland landscape. 13. Future Modifications and Plans None. 14. Software Not applicable. 14.1 Software Description Not applicable. 14.2 Software Access Not applicable. 15. Data Access 15.1 Contact Information Ms. Beth Nelson BOREAS Data Manager NASA GSFC Greenbelt, MD (301) 286-4005 (301) 286-0239 (fax) Elizabeth.Nelson@gsfc.nasa.gov 15.2 Data Center Identification See Section 15.1. 15.3 Procedures for Obtaining Data Users may place requests by telephone, electronic mail, or fax. 15.4 Data Center Status/Plans The TGB-01/TGB-03 NEE data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 16. Output Products and Availability 16.1 Tape products None. 16.2 Film Products None. 16.3 Other Products Comma-separated ASCII files with text delimited by single quotes (‘). 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Not applicable. 17.2 Journal Articles and Study Reports Sellers, P.and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). Sellers, P.and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). Sellers, P.and F. Hall. 1997. BOREAS Overview Paper. JGR Special Issue. Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPSDOC 94). Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPSDOC 96). Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den Hartog, J. Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D. Lettenmaier, and D.E. Wickland. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview and earlyresults from the 1994 field year. Bulletin of the American Meteorological Society. 76(9):1549-1577. Whiting et al., 1991. J. Geophys. Res. 96: 13,067-13,071. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None given. 19. List of Acronyms AES - Atmospheric Environment Services, Canada ASCII - American Standard Code for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System BP - Beaver Pond site, NSA CB - Collapse Bog CF - Collapse Fen CMDL - Climate Monitoring and Diagnostics Laboratory DAAC - Distributed Active Archive Center DTE - Data Terminal Equipment DCE - Data Communication Equipment ECD - Electron Capture Detector EOS - Earth Observing System EOSDIS - EOS Data and Information System FID - Flame Ionization Detector GC - Gas Chromatograph GSFC - Goddard Space Flight Center IRGA - Infrared Gas Analyzer LI-6200 - LI-COR portable photosynthesis system NASA - National Aeronautics and Space Administration NEE - Net Ecosystem Exchange of C02 NSA - Northern Study Area OBS - Old Black Spruce OJP - Old Jack Pine ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park PAR - Photosynthetically Active Radiation SSA - Southern Study Area TCD - Thermal Conductivity Detector TF - Tower Fen TGB-03 - Trace Gas Biogeochemistry Team 3 UNH - University of New Hampshire URL - Uniform Resource Locator YJP - Young Jack Pine site, NSA ZF - Zoltai fen 20. Document Information 20.1 Document Revision Date Written: Last updated: 05-Jun-98 20.2 Document Review Date(s) BORIS Review: 10-Mar-98 Science Review: 20.3 Document 20.4 Citation None given. 20.5 Document Curator 20.6 Document URL Keywords --------------- Net Ecosystem Exchange NEE TGB01_TGB03_NEE.doc 06/11/98