BOREAS TF-07 SSA-OBS Tower Flux and Meteorological Data Summary The BOREAS TF-07 team collected meteorological data as well as energy, carbon dioxide, water vapor, methane, and nitrous oxide flux data at the BOREAS SSA-OBS site. The data were collected from May 24 to September 19, 1994. The data are available 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 TF-07 SSA-OBS Tower Flux and Meteorological Data 1.2 Data Set Introduction Tower-based flux of heat, momentum, H2O, CO2, CH4, and N2O measured by eddy- correlation and/or aerodynamic gradient techniques, over the BOReal Ecosystem- Atmosphere Study (BOREAS) Southern Study Area (SSA) Old Black Spruce (OBS) stand, from day of year 144 to 155, 200 to 209, 251 to 261, in 1994. 1.3 Objective/Purpose The purpose of this study is to determine the contribution of the boreal ecosystem to the greenhouse gas composition of the atmosphere and how this ecosystem responds to environmental conditions. Specific objectives are the following: i) scaling-up of mass and energy surface fluxes from the local scale to the regional scale (spatial representativeness of tower-based measurements), ii) quantification of the effects of ambient conditions and biological processes on gas exchanges in order to carry out a carbon budget of a black spruce stand, iii) determination of differences by conditional analysis of aircraft and tower data, and iv) intercomparison between tower-based fluxes. 1.4 Summary of Parameters Latent heat flux; sensible heat flux; water vapor flux; fluxes and concentrations of carbon dioxide, methane, and nitrous oxide; momentum flux; net radiation; incident solar radiation; mean and standard deviation of wind speed and direction; friction velocity; mean U and V components of wind speed; standard deviation of the U, V, and W components of the wind speed; mean and standard deviation of specific humidity, vapor pressure, and air temperature. 1.5 Discussion Tower Flux (TF)-07 surface fluxes were measured by micrometeorological techniques at the BOREAS SSA-OBS tower. Momentum, CO2, and sensible and latent heat fluxes were measured using the eddy- correlation technique (EC), while methane and nitrous oxide fluxes were measured using either EC or the aerodynamic-gradient techniques (AG). Several measurement periods of isoprene fluxes by the relaxed eddy-accumulation technique (REA) were carried out in collaboration with Dr. Hal Westberg, Trace Gas Biogeochemistry (TGB)-10. The measurements were made at 20 m above the ground (about 12 m above the displacement plane). Wind velocities and temperature were measured with a sonic anemometer-thermometer (Kaijo-Denki DAT-310). Sensible heat flux was corrected for water vapor transfer (Schotanus et al., 1983). The sonic anemometer and the intake tubes of the closed-path analyzers were located on a boom 1.65 m long parallel to the soil surface. By rotating and/or moving the boom to one of the two ends of the south side of the tower, the sensors were oriented in the prevalent wind direction. CO2 and H2O concentrations were measured in fast- response absolute mode with an infrared gas analyzer (IRGA; LI-COR 6262) equipped with a 4-m-long sampling tube. The flow in the inlet was turbulent, and the signals were time adjusted to maximize the correlation with the vertical wind velocity. The CO2 fluxes were corrected for density fluctuations associated with water vapor (Webb et al., 1980) and for sensitivity of the IRGA to water vapor, as determined in our laboratory (Pattey et al., 1992). A detailed description of the data acquisition system can be found in Pattey et al., 1995. Methane and nitrous oxide gradients between 16 and 24 m above the ground were measured with tunable diode lasers (Campbell Scientific, TGA). The eddy diffusivity coefficient, K, was calculated based on the measurements from a sonic anemometer. Isoprene fluxes were measured using REA (Pattey et al., 1993). Isoprene concentration analyses were carried out by Dr. Westberg's team (TGB-10). All the fluxes were calculated on a 30-minute basis. Measurements were carried out during the three Intensive Field Campaigns (IFCs) in 1994 between calendar days 144-155 (May-June), 200-209 (July), and 251-261 (September). 1.6 Related Data Sets BOREAS TF-09 SSA-OBS Tower Flux, Meteorological, and Soil Temperature Data BOREAS TF-05 SSA-OJP Tower Flux, Meteorological, and Soil Temperature Data BOREAS TF-03 NSA-OBS Tower Flux, Meteorological, and Soil Temperature Data BOREAS TF-04 SSA-YJP Tower Flux, Meteorological, and Soil Temperature Data BOREAS TF-11 SSA-Fen Tower Flux, Meteorological, and Soil Temperature Data 2. Investigator(s) 2.1 Investigator(s) Name and Title Dr. Raymond L. Desjardins Project Leader, Air Quality Group, Dr. Elizabeth Pattey Research Scientist, Air Quality Group 2.2 Title of Investigation Areal Estimates of Mass and Energy from a Boreal Forest Biome 2.3 Contact Information Contact 1 --------- Dr. Elizabeth Pattey Centre for Land and Biological Research Resources Agriculture and Agri-Food Canada Ottawa, ONT. CANADA (613) 759-1523 (613) 996-0646 (fax) PATTEYE@GW.AGR.CA Contact 2 --------- K. Fred Huemmrich University of Maryland NASA GSFC Greenbelt, MD (301) 286-4862 (301) 286-0239 (fax) Karl.Huemmrich@gsfc.nasa.gov 3. Theory of Measurements Ec provides the most direct measurement of the flux of a gas at the land- atmosphere interface. It provides measurements of gas exchange without disturbing the environment under study and integrates the flux over a mosaic of different sources and sinks. The instantaneous transfer across a horizontal plane per unit area and per unit time is given by F = WS, where W is the vertical velocity, and S is the mixing ratio of the gas of interest. Because turbulent transfer is intermittent, it must be averaged over a certain time or distance to obtain a representative sample. The mean flux of a gas over a horizontally homogeneous surface under steady-state conditions is given by F = , where W' and S' are the fluctuations from their mean. Reasonably stationary conditions, little horizontal advection and no chemical reaction involving the gas of interest within the air column below the measuring system are required for accurate flux measurements. These effects need to be taken into account to minimize flux divergence with height, which can lead to significant errors of surface flux estimates from aircraft-based systems (Desjardins et al., 1992). 4. Equipment 4.1 Sensor/Instrument Description A three-axis sonic wind anemometer/thermometer from Kaijo Denki Co. (Japan) was used for measuring the fluctuations of the three wind components (U, V, W) and the temperature (T). The sonic is equipped with 90-degree probes and has a 20-cm open-path. The sonic outputs the following signals: U and V at 90°, the horizontal wind speed (U1= SQRT(U2+V2)), and theta the wind angle relative to the sonic position, in addition to W and T. An IRGA from LI-COR Inc., model 6262, was used for measuring water vapor and CO2 fluctuations, equipped with a pressure transducer between the outlet of the sample cell and the pump. A tunable-diode laser (TDL) from Campbell Scientific equipped with the laser, sample and reference detector was used for measuring CH4 fluctuations and N2O fluctuations. A pyranometer from LI-COR Inc., model LI-200s was used to measure incoming solar radiation. 4.1.1 Collection Environment Measurements were collected in intervals from late May through mid-September 1994. Over the data collection periods, the low temperatures experienced did not drop below freezing and the high temperatures were not over 27 °C. 4.1.2 Source/Platform Above-canopy measurements were made from a 23-meter double scaffold walk-up tower. 4.1.3 Source/Platform Mission Objectives The objectives were to measure energy and momentum fluxes and fluxes of CO2, CH4, and N2O from a boreal black spruce stand and to obtain diurnal patterns of regional fluxes by combining aircraft- and tower-based flux measurements. 4.1.4 Key Variables Sensible heat flux, latent heat flux, momentum flux, trace gas fluxes of CO2, CH4, and N2O. 4.1.5 Principles of Operation Three-axis sonic wind anemometer/thermometer from Kaijo Denki: The ultrasonic anemometer thermometer measurement is based on the characteristics of sound waves in the atmosphere. Sound waves are propagated in air linearly at an essentially constant speed of approximately 340 m/s. Ultrasonic propagating speed in moving air, however, is slightly variable, traveling faster in a tail wind and slower in a head wind. The wind speed is deducted from the duration taken by ultrasonic pulses to travel between two ultrasonic pulse transducer elements facing each other at a fixed distance. Two ultrasonic pulse signals are alternatively emitted in opposite directions. The sound velocity in air fluctuates with temperature, as well as with humidity and atmospheric pressure. Air temperature fluctuations can be measured assuming longer pressure and humidity fluctuating cycles. In fact, humidity fluctuations should be taken into account to correct sensible heat flux as proposed by Schotanus et al. (1983). IRGA from LI-COR: Heteroatomic molecules are known to absorb infrared radiation at specific wavelengths; each gas has a specific absorption spectra. Radiation absorption at a given wavelength follows the Beer-Lambert Law, i.e., is a function of the path length of the measuring cell, the extinction coefficient at the specified wavelength, and the molar concentration of the heteroatomic molecule in air. The wavelength for CO2 absorption shows sensitivity to water vapor that is attenuated by using filters. As the temperature of the cell is measured, the signals can be corrected for density fluctuations due to temperature. To be read in fast- response mode, signals should be linearized and pressure within the measuring cell included in the linearization equation. TDL from Campbell Scientific: The trace gas analyzer system (TGAS, Campbell Scientific) measures absolute concentrations of trace gas species by infrared absorption techniques using a TDL source. The TGAS is a fast-response closed-path analyzer, in which absorption of a specific infrared laser line by trace gas molecules (i.e. either methane or nitrous oxide) is detected. The emission lines are selected to minimize the error caused by absorption from interfering species. The laser intensity absorption follows the Beer-Lambert law of attenuation and is a function of the absorption cross-section, the path-length, and the concentration of methane or nitrous oxide molecules. In the TGAS, the laser beam absorption is measured simultaneously in a 155-cm long sample cell and in a 5-cm-long reference cell filled with either 3.05% certified methane or 0.2668% certified nitrous oxide in nitrogen maintained at about 8 kPa. The number of molecules in the sample cell is equal to the known number of molecules in the reference cell multiplied by the ratio of path-lengths between the reference and sample cell and multiplied by the ratio of the wavelength integrated absorbance between the sample and the reference cell. Both cells are maintained at low pressure to limit pressure broadening of methane or nitrous oxide absorption line. The operating temperature of the TGAS diode laser is in the range of 90 K, which is maintained with liquid nitrogen. Most TDLs are very sensitive to vibration. Pyranometer from LI-COR: The pyranometer is constituted of thermopiles. It is used to measure incoming solar radiation. 4.1.6 Sensor/Instrument Measurement Geometry The sonic anemometer and the intake tubes of the closed-path analyzers were located on a boom 1.65 m long, parallel to the soil surface. The boom was mounted on a rotating table to orient the sensors in the prevalent wind direction, and on a sliding carriage to access both ends of the south side of the tower. The infrared CO2 and H2O analyzer (IRGA; LI-COR 6262) was located on the 18.7-m-high platform close to the south side of the tower. It was equipped with a 4-m sampling tube. The TDLs were located on the ground. The methane analyzer was located between the tower and the hut and had a 34.5-m-long sampling tube, while the N2O analyzer was hooked to the ceiling of the hut and had a 61.5-m-long sampling tube. The conditional sampling system was located on the same platform as the IRGA. Methane and nitrous oxide gradients were measured between 16 and 24 m above the ground. 4.1.7 Manufacturer of Sensor/Instrument Sonic Anemometer: Kaijo Denki Co. GENEQ, Inc. 7978 EST, rue Jarry Montreal, QUE., H1J 1H5 H2O CO2 IRGA and Pyranometer: LICOR, Inc. P.O. Box 4425 Lincoln, NE 68504 TDL: Campbell Scientific P.O. Box 551, Logan, UT 84321 Fine-Wire Thermocouple: Campbell Scientific P.O. Box 551, Logan, UT 84321. Net Radiometer: Middleton Instruments, Inc. P.O. Box 442 South Melbourne, Victoria, 3205, Australia Data Logging System: Campbell Scientific P.O. Box 551, Logan, UT 84321 4.2 Calibration 4.2.1 Specifications The manufacturer calibration of the LI-6262 to establish the linearization functions was done in July 1993. The field calibration of the LI-6262 was done by removing the offsets on the CO2 and H2O signals by passing nitrogen through the reference and sample cells, and by adjusting the gain on CO2 channel by passing known CO2 concentration in dry air and by passing known water vapor concentration in air to adjust the H2O channel. The CO2 standard was cross- referenced with BOREAS standards. During IFC-1 and -2, a 10 liter bag was filled with ambient air and connected via a dewpoint hygrometer to the sample cell of the LI-6262. During IFC-3, the LI- 610 dewpoint generator was used to produce air at known water vapor concentration. The sonic anemometer was factory calibrated, except for the temperature, for which a linear correction function was established after IFC-3 in Ottawa against another sonic anemometer. The other signals were well calibrated. Calibration of the TDLs: the reference cell has a known methane or nitrous oxide certified concentration flowing through it, and the signal is compensated for pressure variation, although the pressure is maintained at a steady value. 4.2.1.1 Tolerance None given. 4.2.2 Frequency of Calibration None given. 4.2.3 Other Calibration Information None given. 5. Data Acquisition Methods The signals of the instruments were collected at 20 Hz through a Labmaster board (Scientific Solutions) (analog to digital (A/D) converter) and preprocessed in real time on a microcomputer. The vertical wind speed was high-pass filtered at 0.001 Hz by a digital filter. Sums, sums of square, and sum of cross-product were accumulated over 15 seconds and saved on a binary format without being converted into the proper units, so that they could be processed again if the calibration factor needed to be changed. Nonlinearized signals, like those of the LI-COR 6262, were linearized in real time before being summed. The tower had the capability to rotate to be aligned in the mean horizontal wind direction. The data acquisition and control system was able to control a fast-response valve to perform conditional sampling based on the vertical wind velocity signal. Nonmethane hydrocarbon was collected in canisters for several periods following REA (Businger and Oncley, 1990; Pattey et al., 1993). Subcanopy signals were collected via a CR-21X (Campbell Scientific) data logger. 6. Observations 6.1 Data Notes None. 6.2 Field Notes None. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage All data were collected at the BOREAS SSA-OBS site. North American Datum of 1983 (NAD83) coordinates for the site are latitude 53.98717° N, longitude 105.11779° W, and elevation of 628.94 m. 7.1.2 Spatial Coverage Map Not applicable. 7.1.3 Spatial Resolution The fluxes measured at 12 m above the displacement height integrate surface contribution, which can be described by footprint functions. The surface contributing to the flux mainly depends on the horizontal wind velocity, the wind direction, surface roughness, the atmospheric stability, and the height of measurements. The spatial coverage can be evaluated by using footprint algorithms (Schuepp et al., 1990; Horst and Weil, 1992). Flux measurements, for which the wind was blowing over a sector including the hut, the ecology tower, and/or the access path, were discarded. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Surface flux data were collected during IFC-1 (24 May to 8 June), IFC-2 (19 July to 1 August), and IFC-3 (5 to 19 September), 1994. 7.2.2 Temporal Coverage Map Not available. 7.2.3 Temporal Resolution The reported data values are 30 minute averages with the reported time corresponding to the start of the sampling period. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (tf07flux.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (tf07flux.def). 8. Data Organization 8.1 Data Granularity All of the SSA-OBS Tower Flux and Meteorological Data are contained in one data set. 8.2 Data Format 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 (tf07flux.def). 9. Data Manipulations 9.1 Formulae See Section 9.1.1. 9.1.1 Derivation Techniques and Algorithms Momentum flux (FU; N m-2): FU= rhoa where: W: vertical wind velocity (m s-1) U1: horizontal wind speed (m s-1) < >: average over the averaging period ': fluctuation rhoa: air density (g m-3) Sensible heat flux (FT; W m-2) FT = rhoa Cp where: Cp: air specific heat at constant pressure T: air temperature (C) FT is corrected for humidity and velocity fluctuations (Schotanus et al, 1983) Latent heat flux (FQ; W m-2): FQ = L rhoa MV/MA 10-3 where: L: coefficient of vaporization (J g-1 K-1) MV: molecular mass of water vapor (18 g mol-2) MA: molecular mass of dry air (29 g mol-1) NQ: molar fraction (mmol H2O mol-2 dry air) Flux of trace gases (FS; g m-2 s-1): FS = rhoa MS/MA + rhoS DF where: NS: molar fraction of the species (mol S mol-2 dry air) MS: molecular mass of the species (g mol-1) rhoS: density of the species (g m-3) DF= density fluctuation correction (Webb et al., 1980) Expected sensitivity of trace gases to density fluctuation correction can be found in Pattey et al (1992). For CO2 flux measured by the LI-COR 6262, only density fluctuations due to water vapor fluctuations are involved in the correction. 9.2 Data Processing Sequence The following steps were used to process the data: 1) Collection of 15-s blocks. 2) Sum over the averaging period. 3) Scaling and conversion of binary data to channel units. 4) Mean, standard deviation, and flux calculation. 9.2.1 Processing Steps BORIS staff processed these data by: 1) Reviewing the initial data files and loading them online for BOREAS team access. 2) Designing relational data base tables to inventory and store the data. 3) Loading the data into the relational data base tables. 4) Working with the team to document the data set. 5) Extracting the data into logical files. 9.2.2 Processing Changes None. 9.3 Calculations 9.3.1 Special Corrections/Adjustments None. 9.3.2 Calculated Variables Sensible heat flux, latent heat flux, momentum flux, trace gas fluxes of CO2, CH4, and N2O. 9.4 Graphs and Plots None. 10. Errors 10.1 Sources of Error None given. 10.2 Quality Assessment The data were not verified against wind direction and rejection sector. 10.2.1 Data Validation by Source None given. 10.2.2 Confidence Level/Accuracy Judgment None given. 10.2.3 Measurement Error for Parameters None given. 10.2.4 Additional Quality Assessments None given. 10.2.5 Data Verification by Data Center Data were examined to check for spikes, values that are four standard deviations from the mean, long periods of constant values, and missing data. 11. Notes 11.1 Limitations of the Data Data were collected only during the IFCs in 1994. 11.2 Known Problems with the Data Missing data with TDL-TGAS are associated with vibration problems, analysis of REA samples, and, for IFC-1, pump troubleshooting. 11.3 Usage Guidance None given. 11.4 Other Relevant Information None given. 12. Application of the Data Set These data are useful for the study of water, energy, carbon, and nitrogen exchange in a mature black spruce forest. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description None given. 14.2 Software Access None. 15. Data Access 15.1 Contact for Data Center/Data Access Information These BOREAS data are available from the Earth Observing System Data and Information System (EOS-DIS) 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 15.2 Procedures for Obtaining Data BOREAS data may be obtained through the ORNL DAAC World Wide Web site at http://www-eosdis.ornl.gov/ or users may place requests for data by telephone, electronic mail, or fax. 15.3 Output Products and Availability Requested data can be provided electronically on the ORNL DAAC's anonymous FTP site or on various media including, CD-ROMs, 8-MM tapes, or diskettes. The complete set of BOREAS data CD-ROMs, entitled "Collected Data of the Boreal Ecosystem-Atmosphere Study", edited by Newcomer, J., et al., NASA, 1999, are also available. 16. Output Products and Availability 16.1 Tape Products None. 16.2 Film Products None. 16.3 Other Products These data are available on the BOREAS CD-ROM series. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation None given. 17.2 Journal Articles and Study Reports Businger, J.A. 1986. Evaluation of the accuracy with which dry deposition can be measured with current micrometeorological techniques. J. Clim. and Appl.Meteorol. 25:1100-1124. Businger, J.A. and S.P. Oncley. 1990. Flux measurement with conditional sampling. J. Atmos. Ocean. Tech., 7: 349-352. Chahuneau, F., R.L. Desjardins, E.J. Brach, and R. Verdon. 1989. A micrometeorological facility for eddy flux measurements of CO2 and H2O. J.Clim. Appl. Meteorol. 25: 1100-1124. Desjardins, R.L., P. Rochette, J.I. MacPherson, and E. Pattey. 1992. Measurements of greenhouse gas fluxes using aircraft- and tower-based techniques. In "Agricultural Ecosystem Effects on Trace Gases and Global Climate Change" ASA special publication #55: 45-62. Desjardins, R.L., J.I. MacPherson, L. Mahrt, P. Schuepp, E. Pattey, H. Neumann, D. Baldocchi, S. Wofsy, D. Fitzjarrald, H. McCaughey, and D.W. Joiner. 1997. Scaling up flux measurements for the boreal forest using aircraft-tower combination, Journal of Geophysical Research, 102(D24):29,125-29,134. Horst, T.W. and J.C. Weil. 1992. Footprint estimation for scalar flux measurements in the atmospheric surface layer. Boundary-Layer Meteorol., 59: 279-296. Pattey, E., R.L. Desjardins, F. Boudreau, and P. Rochette. 1992. Impact of density fluctuations on flux measurements of trace gases: implications for the relaxed eddy accumulation technique. Boundary-Layer Meteorol., 59: 195-203. Pattey, E., R.L. Desjardins, and P. Rochette. 1993. Accuracy of the relaxed eddy- accumulation technique, evaluated using CO2 flux measurements. Boundary-Layer Meteorol., 66: 341-355. Pattey, E., R.L. Desjardins , and G. St-Amour. 1997. Mass and energy exchanges over a black spruce forest during key periods of BOREAS 1994. Journal of Geophysical Research, 102(D24):28,967-28,976. Pattey, E., W.G. Royds, R.L. Desjardins, D.J. Buckley and P. Rochette. 1995. Software description of a data acquisition and control system for measuring trace gas and energy fluxes by eddy-accumulation and correlation techniques. Computers and Electronics in Agriculture (submitted for publication). Scheupp, P.H., M.Y. Leclerc, J.I. Macpherson, and R.L. Desjardins. 1990. Footprint prediction of scalar fluxes from analytical solutions of the diffusion equation. Bound. Layer Meteorol., 50:355-373. 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. 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., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 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. Sellers, P.J., F.G. Hall, R.D. Kelly, A. Black, D. Baldocchi, J. Berry, M. Ryan, K.J. Ranson, P.M. Crill, D.P. Lettenmaier, H. Margolis, J. Cihlar, J. Newcomer, D. Fitzjarrald, P.G. Jarvis, S.T. Gower, D. Halliwell, D. Williams, B. Goodison, D.E. Wickland, and F.E. Guertin. 1997. BOREAS in 1997: Experiment overview, scientific results, and future directions. Journal of Geophysical Research, 102(D24):28,731-28,770. Webb, E.K., G.I. Pearman, and R. Leuning. 1980. Correction of flux measurements density effects due to heat and water vapour transfer. Quart. J. R. Met. Soc. 106:85-100. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms A/D - Analog to Digital AG - Aerodynamic Gradient ASCII - American Standard Code for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CD-ROM - Compact Disk-Read Only Memory DAAC - Distributed Active Archive Center EC - Eddy Covariance EOS - Earth Observing System EOSDIS - EOS Data and Information System GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center HTML - HyperText Markup Language IFC - Intensive Field Campaign IRGA - Infrared Gas Analyzer NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration NSA - Northern Study Area OBS - Old Black Spruce ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park PAR - Photosynthetically Active Radiation PC - Personal Computer PPFD - Photosynthetic Photon Flux Density REA - Relaxed Eddy Accumulation REBS - Radiation Energy Balance Systems SSA - Southern Study Area TDL - Tunable-Diode Laser TF - Tower Flux TGA - Trace Gas Analyzer TGB - Trace Gas Biogeochemistry TGAS - Trace Gas Analyzer System URL - Uniform Resource Locator WAB - Wind Aligned Blob WMO - World Meteorological Organization 20. Document Information 20.1 Document Revision Date Written: 04-Oct-1995 Revised: 25-May-1999 20.2 Document Review Date(s) BORIS Review: 08-Apr-1999 Science Review: 20.3 Document ID 20.4 Citation When using these data, please include the following acknowledgment: These data were provided by Drs. E. Pattey and R.L. Desjardins. This work was supported by Agriculture and Agri-Food Canada. If using data from the BOREAS CD-ROMs please also reference the data as: Dr. Raymond L. Desjardins and Dr. Elizabeth Pattey, "Areal Estimates of Mass and Energy from a Boreal Forest Biome." in Collected Data of The Boreal Ecosystem- Atmosphere Study. Eds. J. Newcomer, D. Landis, S. Conrad, S. Curd, K. Huemmrich, D. Knapp, A. Morrell, J. Nickeson, A. Papagno, D. Rinker, R. Strub, T. Twine, F. Hall, and P. Sellers. CD-ROM. NASA, 1999. To cite the BOREAS CD-ROM set as a published volume, use: J. Newcomer, D. Landis, S. Conrad, S. Curd, K. Huemmrich, D. Knapp, A. Morrell, J. Nickeson, A. Papagno, D. Rinker, R. Strub, T. Twine, F. Hall, and P. Sellers, eds. Collected Data of The Boreal Ecosystem-Atmosphere Study. CD-ROM. NASA, 1999. 20.5 Document Curator 20.6 Document URL Keywords: BLACK SPRUCE TOWER FLUX METEOROLOGY SENSIBLE HEAT FLUX LATENT HEAT FLUX CARBON DIOXIDE FLUX CARBON DIOXIDE CONCENTRATION METHANE FLUX METHANE CONCENTRATION NITROUS OXIDE FLUX NITROUS OXIDE CONCENTRATION WATER VAPOR FLUX MOMENTUM FLUX SOLAR RADIATION NET RADIATION AIR TEMPERATURE VAPOR PRESSURE HUMIDITY WIND SPEED TF07_Flux_Met.doc 06/09/99