BOREAS TGB-01/TGB-03 Water Table and Peat Temperature Data over the NSA 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 continuous and manual measurements of water level, air and soil temperatures at the four subsites within the NSA Tower Fen site complex. The measurements were taken to understand the thermal and hydrological gradients associated with each plant community present in the fen. Measurements were taken from May to September 1994 and May to October 1996. 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 Water Table and Peat Temperature Data over the NSA 1.2 Data Set Introduction Trace Gas Biogeochemistry Teams 1 and 3 (TGB-01 and TGB-03) collected automated and manual water table, surface fluctuations, and thermal profile measurements at the Northern Study Area (NSA) Tower Fen (TF) site. These measurements complement the Net Ecosystem Exchange (NEE) measurements to help understand the environmental controls on NEE. Measurements were made from the period of snow melt and thaw through the full growing season to the fall freeze. 1.3 Objective/Purpose 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 taken at the four subsites within the fen in the NSA. 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). 1.4 Summary of Parameters and Variables The water table level, surface fluctuations, and peat temperatures were measured at four locations in the NSA TF site. The water table and peat temperatures were measured at multiple depths for each subsite studied. 1.5 Discussion NEE was measured at four subsites in the NSA fen, designated as collapse bog (CB), collapse fen (CF), 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. 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). 1.6 Related Data Sets BOREAS TGB-04 Substrate Water Table and Sediment Temperature BOREAS TGB-01/TGB-03 NEE Data over the NSA Fen 2. Investigator(s) 2.1 Investigator(s) Name and Title Dr. Timothy R. Moore Professor, Geography Department McGill University 2.2 Title of Investigation Carbon Dioxide and Methane Exchanges Between Wetland and Upland Soils and the Atmosphere. 2.3 Contact Information Contact 1 --------- Dr. Tim R. Moore Department of Geography Montreal, Quebec (514) 398-4961 moore@felix.geog.mcgill.ca Contact 2 --------- Dr. Jill 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 3 Sara Conrad Raytheon STX Corporation NASA GSFC Greenelt, MD (301) 286-2624 (301) 286-0239 Sara.Golightly@gsfc.nasa.gov 3. Theory of Measurements Water Table and Surface Fluctuation: A potentiometer (variable resistor) attached to a float determines the voltage measured by the datalogging device. The potentiometer is calibrated for 1 mV = 1mm of float movement. A datalogger measures this voltage. Temperature Profiles: Copper-constantan thermocouple wire induces a current between the two dissimilar metals according to the temperature at the junction of the two wires. By placing these junctions at known depths along a rod driven into the ground, a temperature profile can be measured by a datalogger, if the temperature of the opposite junction is known. This temperature is known by a direct measurement from the datalogger. To permit all temperatures to be measured by one datalogger, a multiplexer was used to make more measurements than the datalogger alone would allow. 4. Equipment 4.1 Sensor/Instrument Description Instrumentation at all four sites included Campbell Scientific CR10 dataloggers, Campbell Scientific AM416 multiplexers, and 20 turn potentiometers. Multiplexers were used to measure an array of thermocouple rods measuring temperature profiles at several locations within each site. Potentiometers were attached to floats within wells dug into the wetlands to measure the fluctuations of water tables. Surface level fluctuations (where made) used the same method, with the beaded cable connected to a “bog shoe” that sat on the wetland surface and moved up and down with the surface. All data were collected every 1 minute and averaged and saved by the datalogger every 30 minutes. Continuous water table measurements were made with a float and counter weight attached to a wheel and a potentiometer mounted on a platform that rested on top of a wooden post anchored in the clay below the peat. The potentiometer was wired to either a CR10 or CR7 datalogger (Campbell Scientific, Inc., Logan, Utah) and 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 Samples were collected under all environmental conditions. 4.1.2 Source/Platform Ground-mounted datalogger and multiplexers. Water level recorders and surface bog shoe supports were mounted on poles driven deeply into the peat to avoid vertical movement. Thermocouple rods were driven into peat at assigned depths. 4.1.3 Source/Platform Mission Objectives The objective was to collect continuous water table and surface fluctuations and thermal profile measurements of four sites near the NSA TF: TF< ZF, CF, and CB. 4.1.4 Key Variables Water table measurements referenced to the wetland surface. Surface fluctuation measurements referenced to arbitrary datum. Temperature profiles (four measurements) at various locations within each site. 4.1.5 Principles of Operation Water Table and Surface Fluctuation: A potentiometer (variable resistor) attached to a float determines the voltage measured by the datalogging device. The potentiometer is calibrated for 1 mV = 1mm of float movement. A datalogger measures this voltage. Temperature Profiles: Copper-constantan thermocouple wire induces a current between the two dissimilar metals according to the temperature at the junction of the two wires. By placing these junctions at known depths along a rod driven into the ground, a temperature profile can be measured by a datalogger, if the temperature of the opposite junction is known. This temperature is known by a direct measurement from the datalogger. To permit all temperatures to be measured by one datalogger, a multiplexer was used to make more measurements than the datalogger alone would allow. 4.1.6 Sensor/Instrument Measurement Geometry Water Table: Referenced to the average wetland surface height, so a measurement of 0 represents a water table at the wetland surface, and negative values indicate a water table below the wetland surface. Regular manual measurements of water table depth were taken (weekly) for calibration of the electronic readings. Surface Fluctuations: Measured similarly to water table and referenced to an arbitrary datum below the surface determined at the beginning of the measurement period. This was possible because the mounting poles for the water table and surface were sufficiently deep into the peat to prevent their movement as well. Ground Temperatures: Referenced to the average wetland surface height. Measurement depths were set at 5 cm, 10 cm, 20 cm, and 40 cm. 4.1.7 Manufacturer of Sensor/Instrument Thermocouple wire: Type T, Supplier Electrosonic Dataloggers and Multiplexers: Campbell Scientific, Canada Corporation 11564-149th street, Edmunton, AB, Canada, T5M 1W7 (403) 454-2505 (403) 454-2655 (fax) Water Table and Surface Measurement: Bournes Precision Twenty turn potentiometers manufactured by Electrosonic, Inc. 110 Gordon Baker Road Willowdale, ON, Canada M2H 3b3 They were enclosed in PVC electrical boxes and connected to aluminum wheels upon which beaded cable and a float (or bog shoe) are attached. The potentiometers are calibrated for 1 mV of voltage change = 1 mm of float height change. These water level recorders were manufactured by TGB-04. 4.2 Calibration Ground Temperatures: No calibration was necessary becausethe principle of induced current from the contact of dissimilar metals applies. Water Levels and Surface Fluctuations: Potentiometers and machined aluminum wheels were calibrated from previous experiments. Weekly manual measurements of water table depth were taken to ensure proper calibration of the electronic measurements. 4.2.1 Specifications Ground Temperatures: Type T thermocouple rated at +/- 0.01° C maximum error. Water and Surface Levels: Maximum error of 1 mm. 4.2.1.1 Tolerance Ground Temperatures: Range allowable: +/-62.5 oC of datalogger temperature (0- 2.5 mV to datalogger). Water and Surface Levels: Range allowable: largely dependent upon length of beaded cable (0-2.5 V to datalogger). 4.2.2 Frequency of Calibration Instruments were calibrated once before field deployment. Weekly manual measurements of ground temperatures and water and surface levels were also performed. 4.2.3 Other Calibration Information No corrections were required according to the calibration methods described above. 5. Data Acquisition Methods Ground Temperatures: Four thermocouples were affixed within each thermocouple rod and sealed in a waterproof epoxy. Thermocouple wires from each thermocouple rod were wired into the Campbell multiplexer to allow for approximately 16-20 separate measurements at each site. The multiplexer was then connected to the CR10 datalogger and a reference thermocouple was run between the datalogger and multiplexer to measure the multiplexer temperature that served as a reference for all measurements. The datalogger was then instructed to use this multiplexer temperature as the basis for the calculation of all the temperatures found on the thermocouple rods (by differential voltage measurements). Water Level and Surface Fluctuation Recorders: The potentiometer varied the voltage measured by the datalogger as the float (or bog shoe) on the beaded cable rose and lowered due to water table changes. The datalogger measured this changing voltage, which was easily converted into a height change since the potentiometers were calibrated to 1 mV of change being equal to 1 mm of vertical water change. 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. 6. Observations 6.1 Data Notes None. 6.2 Field Notes Throughout the summer, there were no unusual occurrences that would interrupt the data other than standard maintenance, which could have affected the measured parameters for short periods of time (less than 30 minutes). 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) 7.1.2 Spatial Coverage Map Not available. 7.1.3 Spatial Resolution Measurements were taken at collar sites that spanned the full range of hydrologic, plant community, and water chemistry gradients found in the larger peatland complex. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage The first version of the data were collected during the summer of 1994 between 26-May to 16-Sep. Water table and temperature measurements were recorded continuously from approximately 04-May-96 to 23-October-96. 7.2.2 Temporal Coverage Map Not applicable. 7.2.3 Temporal Resolution The data were collected continuously at a frequency of 30 minutes. The value represents the averaged data values for the previous 30 minutes. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (tgb3wd.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (tgb3wd.def). 8. Data Organization 8.1 Data Granularity All of the Water Table and Peat Temperature Data are contained in one dataset. 8.2 Data Format(s) The data files contain 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 (tgb3wd.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 Temperature and water table data from the CR10 and CR7 dataloggers were downloaded every 3-4 days and entered into spreadsheets back at the lab. 9.2.2 Processing Changes Not applicable. 9.3 Calculations If a –888 is present in the dataset, it represents a measurement that was taken, but discarded. If a –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 Instrument error could be caused by wire disconnection or shorting, multiplexer or datalogger malfunction, or battery failure. 10.2 Quality Assessment 10.2.1 Data Validation by Source All data were plotted to determine if there were any outlying data points that were obviously incorrect. 10.2.2 Confidence Level/Accuracy Judgment The confidence level in the dataset is quite high, since no complicated calculations are required and the instrumentation has been used before on similar projects by the members of TGB-03 and TGB-04. Accuracy of the electronically gathered data is also high when compared to manual measurements taken by field workers on a weekly basis. 10.2.3 Measurement Error for Parameters Ground Temperatures: Type T thermocouple rated at +/- 0.01° C maximum error. Water and Surface Levels: Maximum error of 1 mm. 10.2.4 Additional Quality Assessments None required. 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. 11.3 Usage Guidance None required. 11.4 Other Relevant Information None. 12. Application of the Data Set The water table and peat temperature data can be used in connection with the chamber flux and 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 chamber NEE data, can be used to scale the CO2 fluxes from the plot scale to wetland landscape. 13. Future Modifications and Plans These data are in draft format. 14. Software 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 water table 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 American Standard Code for Information Interchange (ASCII) files with text delimited by single quotes (‘). 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Campbell Scientific Corporation CR10 Manual. Campbell Scientific Corporation AM416 Manual. 17.2 Journal Articles and Study Reports Bubier, J.L., T.T. Moore, L. Bellisario, N.T. Comer, P.M. Crill. 1995. Ecological Controls on Methane Emissions from a Northern Peatland Complex in the zone of discontinuous Permafrost, Manitoba, Canada. Global Biogeochemical Cycles. Volume 9, Number 4, pp. 455-470. Roulet, N., S. Hardill, N. Comer, N. 1991. Continuous Measurement of the Depth of Water Table (Inundation) in Wetlands with Fluctuation Surfaces. Hydrological processes. Volume 5, pp. 399-403. 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. 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 early results from the 1994 field year. Bulletin of the American Meteorological Society. 76(9):1549-1577. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None given. 19. List of Acronyms ASCII - Amercan Standard Code for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CB - Collapse Bog CF - Collapse Fen DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System GSFC - Goddard Space Flight Center NASA - National Aeronautics and Space Administration NEE - Net Ecosystem Exchange NSA - Northern Study Area ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park SSA - Southern Study Area TF - Tower Fen TGB-03 - Trace Gas Biogeochemistry Team 3 URL - Uniform Resource Locator (a World Wide Web address) 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: 12-Mar-98 Science Review: 20.3 Document 20.4 Citation None given. 20.5 Document Curator 20.6 Document URL Keywords --------- Peat temperature Water temperature Bog Shoe TGB01_TGB03_WaterTable.doc 06/11/98