BOREAS TF-01 SSA-OA Understory Flux, Meteorological, and Soil Temperature Data Summary The BOREAS TF-01 team collected energy, carbon dioxide, and momentum flux data under the canopy along with meteorological and soils data at the BOREAS SSA-OA site from mid-October to mid-November of 1993 and throughout all of 1994. The data are available in tabular ASCII files. Table of Contents 1 Data Set Overview 2 Investigators 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 Modification 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-01 SSA-OA Understory Flux, Meteorological, and Soil Temperature Data 1.2 Data Set Introduction The Tower Flux-01 team collected understory measurements of heat, carbon dioxide, and momentum fluxes along with meteorological, soil temperature, soil moisture, snow temperature, and tree bole temperature data at the BOReal Ecosystem-Atmosphere Study (BOREAS) Southern Study Area (SSA) Old Aspen (OA) tower site. These measurements were made in conjunction with above canopy and profile measurements made at this site by the TF-02 group. The understory data were collected from mid-October to mid-November of 1993 and throughout all of 1994. 1.3 Objective/Purpose The general objective was to study carbon dioxide and water vapor exchange between the forest and atmosphere at the SSA-OA site. Specific objectives were: * To measure the fluxes of sensible heat, H2O and CO2 above the aspen stand throughout the year. * To obtain from the CO2 flux data estimates of gross photosynthesis and respiration. * To determine the contribution of the hazelnut understory to net ecosystem productivity (NEP). * To determine the effects of environmental factors on stand evapotranspiration and NEP. * To take part in the development of procedures for scaling up component fluxes to the stand level. * To study the processes controlling turbulent transfer of H2O and CO2 within the stand. * To take part in the evaluation of methods of estimating nocturnal CO2 in and above the stand. 1.4 Summary of Parameters The following variables were measured from a 4-m tower under the aspen canopy: latent heat flux, sensible heat flux, CO2 flux, CO2 concentration, momentum flux, Bowen ratio, air temperature, wind speed and direction, friction velocity, water vapor concentration, and relative humidity. Other measurements collected to describe the soil and forest: soil heat flux, soil temperature, soil water potential, soil water content, tree bole temperatures, snow temperatures, net radiation, Photosynthetic Photon Flux Density (PPFD) transmitted through the canopy, and air pressure. 1.5 Discussion In 1993 and 1994, the TF-01 group measured fluxes under the canopy at the SSA-OA site, while the TF-02 group measured above canopy fluxes and profiles at that site. In 1996, the TF-01 group moved its equipment to the top of the 39-meter tower to measure above-canopy fluxes. This document describes the 1993 and 1994 under canopy data collection effort. The fluxes of momentum, sensible heat, latent heat (water vapor), and carbon dioxide using the eddy correlation method were measured at the 6 m height in 1993 and the 4 m height in 1994. These measurements were made on a 6 m tall scaffold tower located above 40 m south of the main flux tower at the OA site. The eddy correlation system consisted of 3-dimensional sonic anemometer (model 1012R2A (Solent) Gill Instruments, Lymington, UK) with a 15-cm path length, an infrared gas (CO2/H2O) analyzer (IRGA) (model 6262, LI-COR Inc. Lincoln, NE) and a krypton open-path hygrometer (model KH20, Campbell Scientific Inc., Logan, UT). Air was drawn at 8.0 L min-1 down 3 m of 3.2-mm inner diameter (i.d.) sampling tubing (model Bev-a-line, Thermoplastic Processes Inc., Sterling, NJ), then down 1.7 m of copper tubing (3 mm i.d.) coiled and sandwiched between two aluminum plates within the same housing as the analyzer and then through the analyzer’s sample cell. To prevent condensation in the sampling tubing, it was heated (2-3 oC above ambient) by passing an electric current through 20-AWG nichrome wire (about 15 ohms resistance) coiled around the exterior of the tubing. The pump (model DOA-V191-AA diaphragm pump, Gast Inc., Dayton, OH) was located down stream of the sample cell resulting in the sample cell pressure being about 22 kPa less than atmospheric pressure. The delay time was 0.8 s. The IRGA was operated in absolute mode with dry air at zero CO2 concentration flowing through the reference cell at 25 cm3 min-1. The KH20 hygrometer was operated continuously to evaluate signal delay time and any attenuation resulting from the sample tubing (Leuning & King 1992; Lee et al. 1994). Supporting measurements included soil heat flux at the 3-cm depth measured using nine soil heat flux plates (two model F, Middleton Instruments, Melbourne, Australia, and seven home-made, following Fuchs and Tanner (1968)) along a 20-m transect: average temperature of the surface 3 cm of the forest floor using two integrating thermometers; a soil temperature profile at depths of 2, 5, 10, 20, 50, and 100 cm (CSI direct-burial copper-constantan thermocouples); snow temperature (30-gauge chromel-constantan thermocouples); tree bole temperatures at 0.2, 4.0, 8.0, 12.0, and 15.8 cm (thermocouple wire); net radiation and PPFD (Swissteco net radiometer and LI-COR quantum sensor carried on a tram which traveled back and forth along a 65-m transect on two steel wires suspended 3-4 m above the ground) above the understory; air humidity below (model HMP-35C sensor, Vaisala, Inc., Woburn, MA) the overstory; wind speed and direction below the overstory (model 05031 vane propeller anemometer, R.M. Young Co., Traverse City, MI); and precipitation measured using a weighing rain gauge (Belfort Instrument Co., Baltimore, MD). 1.6 Related Data Sets BOREAS TF-01 SSA-OA Tower Flux, Meteorological, and Soil Temperature Data BOREAS TF-01 SSA-OA Soil Characteristics Data BOREAS TF-02 SSA-OA Tower Flux, Meteorological, and Precipitation Data BOREAS TF-09 SSA-OBS Tower Flux, Meteorological, and Soil Temperature Data 2. Investigator(s) 2.1 Investigator Name and Title Prof. T. Andy Black University of British Columbia Department of Soil Science 2.2 Title of Investigation Boreal Forest Atmosphere Interactions: Exchanges of Energy, Water Vapor and Trace Gases (SSA-OA) 2.3 Contact Information Contact 1: Mr. Zoran Nesic University of British Columbia Department of Soil Science Vancouver, BC CANADA (604) 822-3479, 822-5654(Lab) (604) 822-8639 (fax) NESIC@PPC.UBC.CA Contact 2: Prof. T. Andy Black University of British Columbia Department of Soil Science Vancouver, BC CANADA (604) 822-2730 (604) 822-8639 (fax) ablack@unixg.ubc.ca Contact 3: 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 Note: Equations and special characters are visible only in the MSWord version of this document. Measurements of the fluxes of momentum, sensible heat, water vapor, and CO2 were made with the eddy covariance technique. Velocity components, air temperature, water vapor density, and CO2 concentration in the air were sampled rapidly, and calculations of relevant covariances were performed from these samples to obtain the fluxes. For example, the flux of CO2 was determined as follows: where is the departure of the vertical velocity component from its mean over the averaging interval, usually 30 minute, and is the departure of CO2 concentration from its mean. At the overstory level, three rotations in the coordinate transformation are applied to the flux data to make the lateral component ( ), vertical component( ), and covariance ( ) of the wind vector equal to zero. At the understory level, however, only the mean lateral wind velocity component was rotated to zero under the suspicion that nonzero mean vertical velocities are possible within the trunk space. Webb, Pearman, and Leuning (1980) (WPL) corrections were made to the water vapor and carbon dioxide fluxes measured using the closed-path LI-COR 6262 infrared gas analyzer (IRGA). Broadening correction was done, but not on-line (see Chen et al., 1998, for summary of theory). 4. Equipment 4.1 Sensor/Instrument Description 4.1.1 Collection Environment Measurements were collected from mid-April to the end of 1996. Over that time period, temperature conditions from less than -10 °C to over 25 °C were experienced. 4.1.2 Source/Platform A 37-m walkup scaffold main tower and a 6-m scaffold tower about 40 m from the main tower. 4.1.3 Source/Platform Mission Objectives The objective of the flux tower was to support instrumentation for the study of the fluxes of CO2, energy, water vapor, and momentum between the forest and atmosphere at the SSA-OA. 4.1.4 Key Variables Variables measured using eddy covariance: CO2 and water vapor fluxes, momentum fluxes, sensible heat fluxes, latent heat fluxes. Supporting meteorological variables: net radiation and PPFD under the canopy, wind speed, wind direction, air temperature, relative and absolute humidity, air temperature, soil temperature, soil heat flux, soil moisture, soil water potential, snow temperature, tree bole temperature, precipitation. 4.1.5 Principles of Operation A sonic anemometer determines the wind speed by a pair of transducers acting alternately as transmitters and receivers, sending pulses of high frequency ultrasound between themselves. The 3-D sonic has three pairs of transducers arranged in nonparallel axes. The LI-COR 6262 CO2/H2O analyzer are based on the difference in absorption of infrared radiation passing through two gas sampling cells. The reference cell is used for a gas of known CO2 or H2O concentration, and the sample cell is used for a gas of unknown concentration. Infrared radiation is transmitted through both cell paths, and the output of the analyzer is proportional to the difference in absorption between the two. The principles of operation of most of the supporting instruments can be found in Pearcy et al. (1991) and Fritschen and Gay (1979). 4.1.6 Sensor/Instrument Measurement Geometry Beneath aspen canopy flux measurement sensors were supported by a 2.1-m long horizontal boom at a bearing of 238o fastened to the side of 6-m tall scaffold- type understory tower located approximately 40 m from the main tower. Under canopy measurements included soil heat flux measured at the 3-cm depth using nine soil heat flux plates (two model F, Middleton Instruments, Melbourne, Australia, and seven homemade, following Fuchs and Tanner (1968)) along a 20-m transect; average temperature of the surface 3 cm of the forest floor using two integrating thermometers, a soil temperature profile at depths of 2, 5, 10, 20, 50, and 100 cm (CSI direct-burial copper-constantan thermocouples), and tree bole temperatures at 0.2, 4.0, 8.0, 12.0, and 15.8 cm into the bole (thermocouple wire). Tree bole temperatures were measured in aspen trees using thermocouples placed in the bole at several depths determined from the north side of the tree. The temperatures were measured at 3.12 m height for the 0.2 cm depth, 3.16 m height for the 4.0 cm depth, 3.18 m height for the 8.0 cm depth (the center of the bole), at 3.16 m height for the 12 cm depth (4 cm depth from south side), and at 3.12 m height for the 15.8 cm depth (0.2 cm depth from south side). In addition, a measurement of the hazelnut stem temperature was made at 0.7 m height and 0.2 cm depth. 4.1.7 Manufacturer of Sensor/Instrument Solent sonic anemometer: Gill Instruments Limited Solent House Cannon Street Lymington Hmpshire SO41 9BR United Kingdom DAT-310 sonic anemometer: Kaijo-Denki Co., Ltd. No 19.1 Chrome Kanda-Nishikicho Chiyoda-Ku Tokyo 101 Japan Li-Cor LI-6262 IRGA, 190-SB PPFD, and LAI-2000 PCA: LI-COR Inc. P.O. Box 4425/4421 Superior Street Lincoln, NE 68504 (303) 499-1701 (303) 499-1767 (fax) KH2O krypton hygrometer: Campbell Scientific P.O. Box 551 Logan, UT 84321 CN-1 net radiometer: Middleton Instruments, Inc. P.O. Box 442 South Melbourne Victoria, 3205 Australia S-1 net radiometer: Swissteco Instruments Inc. Stegweg, Eichenwies, CH-94633 OBERRIET SG Switzerland PSP pyranometer and PIR pyrgeometer: The Eppley Laboratory, Inc. 12 Shefield Ave. P. O. Box 419 Newport, RI 02840 (401) 847-1020 (401) 847-1031 (fax) 05031 vane propeller anemometer: R.M. Young Co. Traverse City, MI Distributor: Campbell Scientific P.O. Box 551, Logan, UT 84321 (801) 753-234 (801) 752-3268 Soil temperature (burial) Campbell Thermocouple, Copper-constantan thermocouple: Campbell Scientific P.O. Box 551, Logan, UT 84321 (801) 753-2342 (801) 752-3268 (fax) 4000 IR thermometer: Everest Interscience, Inc. P.O. Box 3640 Fullerton, CA 92634-3640 (714) 992-4461 M1 dewpoint hygrometer (with D2 sensor): General Eastern Instruments Corp. Watertown, MA HMP-35C Vaisala humidity sensor: Vaisala, Inc. Woburn, MA Distributor: Campbell Scientific P.O. Box 551 Logan UT 84321 (801) 753-2342 (801) 752-3268 (fax) Soil heat flux plate (model F): Middleton Instruments, Inc. P.O. Box 442 South Melbourne Victoria, 3205 Australia Time domain reflectometry (TDR): G.S. Gabel Corp. Victoria, BC, Canada CS105 Barometer: Vaisala, Inc. Woburn, MA Distributor: Campbell Scientific P.O. Box 551 Logan, UT 84321 (801) 753-2342 (801) 752-3268 (fax) TE525 Tipping-bucket rain gauge: Texas Electronics Distributor: Campbell Scientific P.O. Box 551 Logan, UT 84321 (801) 753-2342 (801) 752-3268 (fax) Weighing rain gauge: Belfort Instrument Co. 1600 S. Clinton Street Baltimore, MD 21224 21x, CR10 Data logging system: Campbell Scientific P.O. Box 551, Logan, UT 84321 (801) 753-2342 (801) 752-3268 (fax) TD-4X2N diaphragm pump: Brailsford Co. 670 Milton Road Rye, NY 10580 (914) 967-1820 (914) 967-1836 (fax) DOA-V191-AA diaphragm pump: Gast, Inc. P.O. Box 97 Benton Harbor, MI (616) 926-6171 (616) 925-8288 (fax) Bev-a-line tube: Thermoplastic Processes, Inc. Sterling NS Dekoron tubing: Wirex Controls Ltd. 9446 McLaughlin Road N. Unit #27 Brampton, ON Canada, L6X 4H9 (905) 459-0742 (905) 450-8216 4.2 Calibration 4.2.1 Specifications In 1994, zeroing and calibration of the LI-6262 IRGA was done manually, using 350 ppm CO2 cylinders (Medigas) calibrated using TF02 (AES) cylinders and a LI- COR dew point generator. 4.2.1.1 Tolerance CO2 concentration was accurate to within ± 1 mmol mol-1. 4.2.2 Frequency of Calibration Not given. 4.2.3 Other Calibration Information None. 5. Data Acquisition Methods The eddy covariance system consisted of a 3-D sonic anemometer/thermometer (SOLENT 1012R2A) for detecting the three velocity components and air temperature, the latter being derived from the speed of sound following Kaimal and Gaynor (1991), an open-path H2O krypton gas analyzer for measuring water vapor density in the air, and a closed-path dual H2O/CO2 IRGA (LI-COR 6262) for measuring water vapor density and CO2 concentration in the air. The Solent sampled the wind speed components at 20.83 Hz, and its analog-to digital converter sampled the LI-COR signals at 10 Hz. Prior to sampling, the latter signals had been passed through a passive filter with a 7 Hz cut-off frequency. Spectral analysis showed that frequencies above 1 Hz made almost no contribution to fluxes. For the flux system, all raw data were recorded using PC systems with back-up tape drives. Half-hour fluxes were calculated online. For other measurements, all those data were recorded by data loggers (model 21X, Campbell Scientific, Inc., Logan, UT), which were networked together, using the model MD-9 network interface, along with the main system. Every three hours, this network automatically transferred (using PC ANYWHERE software, Symantec Corp.) all data from the loggers to a network computer. 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-OA site in the Prince Albert National Park (PANP). North American Datum of 1983 (NAD83) coordinates for the site are latitude 53.62889° N, longitude 106.19779° W, and elevation of 600.63 m. The understory measurements were collected from a 6-m scaffold tower about 40 m from the main tower. 7.1.2 Spatial Coverage Map Not applicable. 7.1.3 Spatial Resolution Although the eddy covariance measurement is made at one point, it is well known that the fluxes measured with this technique can represent fluxes averaged over a relatively large area. An analysis of the upwind land surface area that contributes to a scalar flux measurement, often referred to as “fetch” or “footprint,” is crucial in understanding the origins of the flux and any possible influences of spatial heterogeneity. According to Blanken’s (1997) results (using Schuepp et al., 1990, model), the cumulative flux at 39 m reached 80% of the total flux at an upwind distance of 1,200 m under neutral conditions, 900 m under typical daytime stability conditions, and 2,700 m under typical nighttime stability conditions. The corresponding values for the 4-m height (above the understory) were 130, 80, and 300 m. Baldocchi (1997) suggests the latter values are overestimates. . From the above results, there was adequate fetch at the OA site because the forest extended for at least 3 km in all directions. 7.1.4 Projection None. 7.1.5 Grid Description None. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Undercanopy data were collected from 12-October to 13-November-1993 and from 1- January to 31-December-1994. 7.2.2 Temporal Coverage Map None. 7.2.3 Temporal Resolution The data reported are 30-minute statistical mean values. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (tf01uflx.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (tf01uflx.def). 8. Data Organization 8.1 Data Granularity All of the TF-01 SSA-OA Understory Flux, Meteorological, and Soil Temperature Data are contained in one dataset. 8.2 Data Format 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 (tf01uflx.def). 9. Data Manipulations 9.1 Formulae 9.1.1 Derivation Techniques and Algorithms There are many equations and formulae used in the calculations of fluxes from the raw voltage signals. Readers are referred to the relevant references for details. 9.2 Data Processing Sequence 9.2.1 Processing Steps Averages, variances, and covariances are calculated in real time, and coordinate rotation is applied on the half-hourly covariances and variances. WPL corrections were made to the water vapor and carbon dioxide fluxes measured using the closed-path LI-COR 6262 IRGA. 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 WPL corrections were made to the water vapor and carbon dioxide fluxes measured using the closed-path LI-COR 6262 IRGA. Broadening correction was done, but not online (see Chen et al., 1998, for summary of theory). 9.3.2 Calculated Variables The Bowen ratio is the ratio of the sensible to latent heat flux. The soil heat storage rate is the rate of change of heat storage in the 0-3 cm surface layer calculated from the gravimetric soil water content and the mean integrated soil temperature. The soil surface heat flux density is the sum of the 3 cm soil heat flux and the soil heat storage rate. 9.4 Graphs and Plots See Black et al., 1996; Chen et al., 1998; Blanken, 1997; and Yang, 1998. 10. Errors 10.1 Sources of Error See Section 10.2.1. 10.2 Quality Assessment 10.2.1 Data Validation by Source Data were checked and flagged for various conditions in the original data base at UBC (Z. Nesic). Relatively little data were missing in 4 m measurements in 1994 and 39 m in 1996. There are several sources of error in the measurements. These are coded, based on field notes, in the COMMENTS column. The following are the definitions of these codes: P = all sensors "parked" in a tower shelter for protection (e.g. high winds). Z = zero check on LiCor B = daily backup of data files C = computer crash S = starting time of a run, if not on the half hour (e.g. S18:50:30). RK = rotated krypton 90 degrees CK = cleaned krypton SK = suspect snow on krypton SS = suspect snow on sonic anemometer/thermometer AP = adjusted LiCor sampling pump TC = zero gas tank change RT = repair zero gas tank PF = power failure PP = suspect pulp and paper mill influence CS = communication problem with sonic anemometer/thermometer ZE = data compression error due to incorrect CPU time The DATA_QUALITY_FLAG column contains four data quality flags: Flag one is for the sonic anememeter/thermometer. The low status of this flag (0) indicates problems with the anemometer/thermometer and its built-in Analog to Digital (A/D) card. This affected all measurements containted in this data file. Flag two is for the closed-path anlayzer (Licor6262) in measuring CO2. The low status of this flag indicates that the analyzer was not performed properly. The measurements of MEAN_CO2_CONC_4M, SDEV_CO2_CONC_4M, and CO2_FLUX_BELOW_CNPY are of poor quality. Flag three is for the closed-path anlayzer (Licor6262) in measuring H2O. The low status of this flag indicates that the analyzer was not performed properly. The measurements of MEAN_LIC_ABS_HUM_4M, SDEV_LIC_ABS_HUM_4M, and LIC_LATENT_HEAT_FLUX_4M are of poor quality. Flag four is for the open-path analyzer (krypton). The low status of this flag indicates problems with this analyzer, mostly as a result of precipitation landing on the sensor. Measurements made with this analyzer, including MEAN_KRYPTON_ABS_HUM_4M, SDEV_KRYPTON_ABS_HUM_4M, and KRYPTON_LATENT_HEAT_FLUX_4M are poor in quality. Some runs with this flag set high might also have be interfered by precipitation. Users should therefore be careful in interpreting the measurements made with this analyzer. Users are also advised to use MEAN_KRYPTON_ABS_HUM_4M only as the absolute humidity measurement, because this type of open-path analyzers (K20) can have substantial zero drift over a short time period. 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. 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 None given. 11.2 Known Problems with the Data See Section 10.2.1. 11.3 Usage Guidance Read this document carefully or contact Drs. T.A. Black and Z. Chen. 11.4 Other Relevant Information None. 12. Application of the Data Set These data are useful for the study of water, energy, and carbon exchange in a mature aspen forest. 13. Future Modifications and Plans Data collection from the SSA-OA tower continued after 1996. Contact Dr. T.A. Black for information about these data. 14. Software 14.1 Software Description None. 14.2 Software Access None given. 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. 17.2 Journal Articles and Study Reports Baldocchi, D.D. 1997. Flux footprints within and over forest canopy. Boundary- Layer Meteorology, 85, 273-292. Black T.A., G. den Hartog, H.H. Neumann, P.D. Blanken, P.C. Yang, C. Russell, and Z. Nesic. 1996. Annual cycle of water vapor and carbon dioxide fluxes in and above a boreal aspen forest. Global Change Biology, 2, 101-111. Blanken, P.D. 1997. Evaporation within and above a boreal aspen forest. Ph.D. Thesis of UBC , 79-84. Chen, W.J., T.A. Black, P.C. Yang, A.G. Barr, H.H. Neumann, Z. Nesic, P.D. Blanken, M.D. Novak, J. Eley, R.J. Ketler, and R. Cuenca. 1998. Effects of climatic variability on the annual carbon sequestration by a boreal aspen forest. Global Change Biology (in press). Fritschen, L.J. and L.W. Gay. 1979. Environmental Instrumentation. Springer- Verlag, Berlin, New York and Heidelberg. Fuchs, M. and C.B. Tanner. 1968. Calibration and field tests of soil heat flux plates. Soil Science Society of America Proceedings, 32, 326-328. Hook, W.R. and N.J.Livingston. 1996. Errors in converting time domain reflectometry measurements of propagation velocity to estimated of soil water content. Soil Sci. Soc. Amer. J., 59, 35-41. Kaimal, J.C. and J.E. Gaynor. 1991. Another look at sonic thermometry. Boundary- Layer Meteorology, 56, 401-410. Lee X., T.A. Black, and M.D. Novak. 1994. Comparison of flux measurements with open-and closed-path gas analyzers above an agricultural field and a forest floor. Boundary-Layer Meteorology, 67, 1995-202. Leuning R. and K.M. King. 1992. Comparison of eddy covariance measurements of CO2 fluxes by open- and closed-path CO2 analyzers. Boundary-Layer Meteorology, 59, 297-311. Pearcy, R.W., J. Ehleringer, H.A. Mooney, and P.W. Rundel. 1991. Plant physiological ecology: Field methods and instrumentation. Chapman and Hall, London and New York. Schuepp P.H., M.Y. Leclerc, J.I. MacPerson, and R.L. Desjardins. 1990. Footprint prediction of scalar fluxes from analytical solutions of the diffusion equation. Boundary-Layer Meteorology, 50, 355-373. 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):28,731-28,769. Webb, E.K., G.I. Pearman, and R. Leuning. 1980. Correction of flux measurements for density effects due to heat and water vapor transfer. Quarterly Journal of the Royal Meteorological Society, 106, 85-100. Yang, P.C. 1998. Carbon dioxide flux within and above a boreal aspen forest. Ph.D. thesis, University of British Columbia, Vancouver, Canada. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List Of Acronyms A/D - Analog to Digital AES - Atmospheric Environment Service AFM - Aircraft Flux and Meteorology ASCII - American Standard Code for Information Interchange ATD - Atmospheric Technology Division ATI - Applied Technologies, Inc. BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CD-ROM - Compact Disk-Read-Only Memory DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center HTML - Hyper-text Markup Language i.d. - inner diameter IFC - Intensive Field Campaign IRGA - Infrared Gas Analyzer LAI - Leaf Area Index NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration NEP - Net Ecosystem Productivity NSA - Northern Study Area OA - Old Aspen ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park PAR - Photosynthetically Active Radiation PC - Personal Computer PPFD - Photosynthetic Photon Flux Density SRC - Saskatchewan Research Council SSA - Southern Study Area TDR - Time Domain Reflectometry TF - Tower Flux UBC - University of British Columbia URL - Uniform Resource Locator WPL - Webb, Pearman, and Leuning (1980) corrections 20. Document Information 20.1 Document Revision Date Written: 04-Sep-1998 Last Updated: 20-Sep-1999 20.2 Document Review Date(s) BORIS Review: 19-Aug-1999 Science Review: 20.3 Document ID 20.4 Citation When using these data, please include the following acknowledgment: Data were collected and processed by T. A. Black, Z. Nesic of the University of British Columbia. If using data from the BOREAS CD-ROMs please also reference the data as: Black, T.A., Nesic, Z., "Boreal Forest Atmosphere Interactions: Exchanges of Energy, Water Vapor and Trace Gases." 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 AIR TEMPERATURE ASPEN CARBON DIOXIDE CONCENTRATION CARBON DIOXIDE FLUX LATENT HEAT FLUX METEOROLOGY MOMENTUM FLUX NET RADIATION PAR PHOTOSYNTHETIC PHOTON FLUX DENSITY PHOTOSYNTHETICALLY ACTIVE RADIATION PPFD RAINFALL SENSIBLE HEAT FLUX SOIL HEAT FLUX SOIL TEMPERATURE SOIL WATER POTENTIAL SNOW TEMPERATURE TOWER FLUX UNDERSTORY VAPOR PRESSURE WIND SPEED TF01_UnderCanopy_Flux.doc 09/30/99