BOREAS HYD-03 Snow Measurements Summary The BOREAS HYD-03 team collected several data sets related to the hydrology of forested areas. This data set contains measurements of snow depth, snow density in 3-cm intervals, an integrated snow pack density and snow water equivalent (SWE), and snow pack physical properties from snow pit evaluation taken in 1994 and 1996. The data were collected from several sites in both the SSA and the NSA. A variety of standard tools were used to measure the snowpack properties, including a meter stick (snow depth), a 100 cc snow density cutter, a dial stem thermometer and the Canadian snow sampler as used by HYD-04 to obtain a snow pack-integrated measure of SWE. This study was undertaken to predict spatial distributions of snow properties important to the hydrology, remote sensing signatures, and the transmissivity of gases through the snow. 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 HYD-03 Snow Measurements 1.2 Data Set Introduction The data pertaining to this documentation include all snow-related measurements made during the field campaigns. These measurements include snow depth and density in 3-cm intervals and integrated throughout the snow pack as well as snow temperatures. The data were collected from several sites in both the BOReal Ecosystem-Atmosphere Study (BOREAS) Southern Study Area (SSA) and the Northern Study Area (NSA). A variety of standard tools were used to measure the snow pack properties including a meter stick (snow depth), a 100-cc snow density cutter, a dial stem thermometer, and the Canadian snow sampler as used by HYD-04 to obtain a snow pack-integrated measure of snow water equivalent (SWE). 1.3 Objective/Purpose This study was undertaken to predict spatial distributions of snow properties important to the hydrology, remote sensing signatures, and the transmissivity of gases through the snow. 1.4 Summary of Parameters Parameters measured with respect to this documentation are snow depth variability and snow density specific to land cover types at the flux tower sites visited. These data allow the calculation of SWE. Additional parameters measured include snow pack temperatures. 1.5 Discussion This study was conducted under the hypothesis that energy transfer and SWE would vary spatially as a function of both the canopy closure and the distance from tree stems. Therefore, to obtain an accurate spatial average, random locations were measured irrespective of the location of trees. The representativeness of the snow depths to the site depends partially on the number of measurements. Raw measurements of snow depths near tree stems and under different canopy closures are available from the Principal Investigator (PI). Certain snow metamorphic processes are driven by snow pack temperature gradients and an effort was made to measure that variable in the boreal forests. 1.6 Related Data Sets BOREAS HYD-04 Standard Snow Course Data BOREAS HYD-04 Areal Snow Course Data 2. Investigator(s) 2.1 Investigator(s) Name and Title Robert E. Davis Research Physical Scientist U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) 2.2 Title of Investigation Distributed Energy Transfer Modeling in Snow and Soil for Boreal Ecosystems 2.3 Contact Information Contact 1: ---------------- Janet P. Hardy U.S. Army CRREL Hanover, NH (603) 646-4306 (603) 646-4397 (fax) jhardy@.crrel.usace.army.mil Contact 2: ---------------- Dr. Robert E. Davis U.S. Army CRREL Hanover, NH (603) 646-4219 (603) 646-4397 (fax) bert@crrel.usace.army.mil Contact 3: ---------------- David Knapp NASA GSFC Greenbelt, MD (301) 286-1424 (301) 286-0239 (fax) David.Knapp@gsfc.nasa.gov 3. Theory of Measurements Several random snow depth measurements were made over the area around each site to assess the variability of snow depth. At one or more locations in the forest, snow pits were dug and profiles of the snow density and temperature were included in the measurements. The snow density profiles were used to calculate an average snow pack density to test the assumption that average density was more conservative than depth. This assumption proved valid; thus measurements of snow depth, in conjunction with average snow pack density, provide accurate estimates of SWE. SWE is the vertical depth of water that would be obtained by melting the snow. Snow temperature measurements were made in part to initialize the snow process model as well as to provide important information for estimating the timing of snow ablation. 4. Equipment 4.1 Sensor/Instrument Description Centimeter scale (meter stick) - for snow depth measurements. 100-cc snow density cutter - allows weight measurement of 100-cc volume of snow, from which the snow density is determined. The dimensions of the cutter are 3 cm x 5.5 cm x 6 cm. This technique measures snow density at intervals of 3 cm height. Electronic top loader balance - provides weight of snow, which allows determination of snow densities accurate within 5% (cutter and scale together). Canadian snow sampler - measures snow depth and provides data on an integrated snow density and SWE. 4.1.1 Collection Environment All data were collected during winter environments. The equipment used is designed for winter use, so the collection environment was appropriate for these measurements. 4.1.2 Source/Platform Ground. 4.1.3 Source/Platform Mission Objectives This work was undertaken at several sites within the BOREAS modeling area to obtain a better understanding of the variations of snow depth and density in different land cover types. 4.1.4 Key Variables snow depth snow pack density SWE snow temperature 4.1.5 Principles of Operation The centimeter scale is inserted into the snow pack, and the depth of the snow is read from the scale. For snow density, a known volume of snow is weighed and its volume density is then determined from the formula in Section 9.1. Two different techniques were used to determine snow density. One used the 100-cc snow cutter, and the other used the Canadian snow sampler. Snow temperatures are read from a horizontally inserted thermometer. 4.1.6 Sensor/Instrument Measurement Geometry Not applicable. 4.1.7 Manufacturer of Sensor/Instrument Snow density cutter: SNOWMETRICS Box 52 Wilson, WY 83014 (307) 739-9458 Electronic balance: ACCULAB 8 Pheasant Run Newtown, PA 18940 (215) 579-3170 Canadian snow sampler: (No manufacturer’s address was given) 1-Eastern Snow Conference (ESC)-30 snow sampler 1-spring balance for ESC-30 1-cradle 1-measuring stick/ruler (cm). Thermometer: Cole - Palmer Instrument Co. 7425 North Oak Park Ave. Niles, IL 60714-9930 4.2 Calibration The electronic balance was calibrated using a 200-gram calibration weight. Thermometers were calibrated using the ice bath calibration method. This method involves placing the temperature sensors in a well mixed combination of water and ice, which will have a known temperature of 0 °C. Thermometers are then adjusted as close as possible to 0 °C while in the ice bath. 4.2.1 Specifications Not available. 4.2.1.1 Tolerance Electronic balance: Accuracy is within 5% when used in conjunction with snow density cutter (+/- 0.1 g when used alone). Thermometer: Range: -50 °C to 150 °C +/- 0.8% full-scale precision or +/- 1.5 °C Resolution = 0.1 °C 4.2.2 Frequency of Calibration Prior to field use. 4.2.3 Other Calibration Information Not available. 5. Data Acquisition Methods 100-cc Snow Cutter: Snow depth measurements were made with a centimeter scale by walking through the area taking random depth measurements. A zero snow depth occurred when the measurement landed at a tree stem. For the snow density profiles, a representative area was chosen, a vertical exposure of the snow pack was exposed to the north, and snow density measurements were made with the 100cc snow cutter every 3 vertical cm until the entire snow pack was measured (i.e. a 45 cm deep snow pack would require 15 measurements of snow density to obtain the snow pack density profile). Canadian Snow Sampler: The Canadian snow sampler is used by inserting the tube through the snow pack to the soil, twisting the tube, and removing the tube and snow core. The tube and snow core are weighted using the spring scale, and the snow depth is read from the centimeter scale on the tube. Snow Temperature: Snow temperature measurements are made by inserting the thermometer horizontally into the snow pit at 10-cm height intervals. Temperatures are read directly off the thermometer dial to the nearest degree once the thermometer has stabilized. 6. Observations 6.1 Data Notes None. 6.2 Field Notes None. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage Point measurements were scattered over a 1-hectare area within 50 meters of the flux tower, if it was near a flux tower site. The following coordinates are approximate and based on the North American Datum of 1983 (NAD83). SWE: SITE_ID LONGITUDE LATITUDE ------------------------- ---------- ---------- SSA-OBS-HYD03-HYD03-SWE01 -105.11779 53.98717 SSA-AGR-HYD03-HYD03-SWE01 -104.78041 53.57649 NSA-OJP-FLXTR-HYD03-SWE01 -98.62028 55.93011 NSA-9BS-HYD3A-HYD03-SWE01 -97.89026 55.81011 NSA-YBS-HYD03-HYD03-SWE01 -97.87026 55.83011 NSA-MIX-HYD03-HYD03-SWE01 -97.84025 55.85011 NSA-9BS-HYD3B-HYD03-SWE01 -97.82025 55.87011 NSA-YJP-FLXTR-HYD03-SWE01 -98.29027 55.90011 SSA-MIX-110B1-HYD03-SWE01 -105.82606 54.58848 SSA-999-110C1-HYD03-SWE01 -105.82461 54.57386 SSA-ASP-110E1-HYD03-SWE01 -105.81461 54.54696 SSA-BSH-110G1-HYD03-SWE01 -105.81221 54.52526 SSA-ASP-110H1-HYD03-SWE01 -105.8067 54.50956 SSA-BRN-110J1-HYD03-SWE01 -105.8123 54.48146 SSA-ASP-110K1-HYD03-SWE01 -105.81 54.46696 SSA-CLR-110L1-HYD03-SWE01 -105.8024 54.43746 SSA-YJP-122D1-HYD03-SWE01 -104.61914 53.84426 SSA-999-122E1-HYD03-SWE01 -104.61944 53.84916 SSA-MIX-122F1-HYD03-SWE01 -104.62214 53.85586 SSA-MIX-122G1-HYD03-SWE01 -104.60623 53.89836 SSA-999-WSK01-HYD03-SWE01 -106.0705 53.94005 SSA-9OA-FLXTR-HYD03-SWE01 -106.19051 53.63005 NSA-OBS-FLXTR-HYD03-SWE01 -98.48027 55.8801 SSA-OJP-HYD03-HYD03-SWE01 -104.69044 53.92006 SSA-9PR-HYD03-HYD03-SWE01 -105.27048 53.56005 Snow Depth Sites: SITE_ID LONGITUDE LATITUDE ------------------------- ---------- ---------- SSA-OJP-FLXTR-HYD03-SDP01 -104.69203 53.91634 SSA-AGR-HYD03-HYD03-SDP01 -104.78041 53.57649 SSA-WAT-FLXTR-HYD03-SDP01 -106.04122 53.83105 SSA-9OA-FLXTR-HYD03-SDP01 -106.19779 53.62889 SSA-OBS-FLXTR-HYD03-SDP01 -105.11779 53.98717 Snow Pits: SITE_ID LONGITUDE LATITUDE ------------------------- ---------- ---------- SSA-AGR-HYD03-HYD03-SPT01 -104.78041 53.57649 SSA-WAT-FLXTR-HYD03-SPT01 -106.04122 53.83105 SSA-9OA-FLXTR-HYD03-SPT01 -106.19779 53.62889 SSA-OBS-FLXTR-HYD03-SPT01 -105.11779 53.98717 SSA-999-WSK04-HYD03-SPT01 -106.09068 53.9232 SSA-OJP-FLXTR-HYD03-SPT01 -104.69203 53.91634 Snow Temperature: SITE_ID LONGITUDE LATITUDE ------------------------- ---------- ---------- NSA-9BS-HYD3B-HYD03-SHT06 -97.82025 55.87011 NSA-9BS-HYD3A-HYD03-SHT01 -97.89026 55.81011 NSA-9BS-HYD3A-HYD03-SHT02 -97.89026 55.81011 NSA-YBS-HYD03-HYD03-SHT03 -97.87026 55.83011 NSA-MIX-HYD03-HYD03-SHT04 -97.84025 55.85011 NSA-9BS-HYD3B-HYD03-SHT05 -97.82025 55.87011 NSA-YJP-FLXTR-HYD03-SHT01 -98.29027 55.90011 NSA-OJP-FLXTR-HYD03-SHT01 -98.62028 55.93011 NSA-OBS-FLXTR-HYD03-SHT01 -98.48027 55.8801 SSA-9PR-HYD03-HYD03-SHT01 -105.27048 53.56005 Subcanopy Meteorological: SITE_ID LONGITUDE LATITUDE ------------------------- ---------- ---------- SSA-OBS-FLXTR-HYD03-SCM01 -105.11779 53.98717 SSA-OJP-FLXTR-HYD03-SCM01 -104.69203 53.91634 SSA-9OA-FLXTR-HYD03-SCM01 -106.19779 53.62889 Subcanopy Radiation: SITE_ID LONGITUDE LATITUDE ------------------------- ---------- ---------- SSA-OBS-FLXTR-HYD03-SCR01 -105.11779 53.98717 SSA-9OA-FLXTR-HYD03-SCR01 -106.19779 53.62889 SSA-OJP-FLXTR-HYD03-SCR01 -104.69203 53.91634 7.1.2 Spatial Coverage Map Not available. 7.1.3 Spatial Resolution Point source data (snow pits). 7.1.4 Projection The locations of these point sites are based on NAD83. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage 1994: Focused Field Campaign-Winter (FFC-W) (05-Feb-1994 to 15-Feb-1994) and FFC-Thaw (FFC-T) (17-Apr-1994 to 27-Apr-1994) 1996: FFC-W (29-Feb-1996 to 12-Mar-1996) 7.2.2 Temporal Coverage Map 05-Feb-1994 SSA-Prairie 06-Feb-1994 SSA-Old Jack Pine (OJP) 07-08-Feb-1994 SSA: Transect near Montreal Lake (Gamma Calibration Lines) 09-Feb-1994 SSA-Waskesui Lake 10-Feb-1994 SSA-Old Aspen (OA) 13-Feb-1994 NSA: near AYJP on Gilliam Road. 14-Feb-1994 NSA-Young Jack Pine (YJP) 15-Feb-1994 NSA-OJP 17-Apr-1994 NSA-YJP 18-Apr-1994 NSA-Old Black Spruce (OBS) 20-Apr-1994 NSA-OBS 22-Apr-1994 NSA-YJP 24-Apr-1994 NSA-YJP 24-Apr-1994 NSA-YJP 25-Apr-1994 NSA-OJP 26-Apr-1994 NSA-YJP 27-Apr-1994 NSA-OPEN 29-Feb-1996 SSA-OBS 01-Mar-1996 SSA-AG 02-Mar-1996 SSA-OBS 04-Mar-1996 SSA-OA 05-Mar-1996 SSA-OJP 07-Mar-1996 SSA-Namekus 11-Mar-1996 SSA-OJP 12-Mar-1996 SSA-Waskesui 7.2.3 Temporal Resolution Snow depth, SWE: biweekly during FFC-W 1994, 3-5 days during FFC-T 1994, more frequently depending on weather. Snow temperatures: FFC-W 1994 - 1-3 days (less for the upper portion of the snow pack). FFC-T 1994 - Once the snow pack is isothermal at 0 °C during the thaw period, the top portion of the snow pack may show some diurnal temperature fluctuations, but otherwise the snow pack may remain at the melting point until the snow is gone. 7.3 Data Characteristics Data characteristics are defined in the companion data definition files (h03sd96d.def), (h03sp96d.def), (h03swed.def), (h3swe96d.def), and (h03sntmd.def). 7.4 Sample Data Record Sample data format shown in the companion data definition files (h03sd96d.def), (h03sp96d.def), (h03swed.def), (h3swe96d.def), and (h03sntmd.def). 8. Data Organization 8.1 Data Granularity All of the Snow Measurement Data are contained in the following datasets: (h03sd96d.dat), (h03sp96d.dat), (h03swed.dat), (h3swe96d.dat), and (h03sntmd.dat). 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 a single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition files (h03sd96d.def), (h03sp96d.def), (h03swed.def), (h3swe96d.def), and (h03sntmd.def). 9. Data Manipulations 9.1 Formulae To determine snow pack SWE: Snow depth (mm) x [snow density (kg/m3)/1000] = SWE (mm) 9.1.1 Derivation Techniques and Algorithms Not applicable. 9.2 Data Processing Sequence 9.2.1 Processing Steps For snow density and snow water equivalence: 1). Determine mean snow depth at site. 2). Determine mean snow pack density at site (if more than one snow pack density measurement exists at any site then average the means). 3). Use formula above to calculate SWE. 9.2.2 Processing Changes None. 9.3 Calculations 9.3.1 Special Corrections/Adjustments None. 9.3.2 Calculated Variables None. 9.4 Graphs and Plots None. 10. Errors 10.1 Sources of Error 1. In measuring snow depth, the probe may at times hit a fallen branch or understory and underestimate snow depth at that point. 2. Snow pack density data were often derived from a single snow pit evaluation. Error would be reduced if it was practical to obtain several measurements of mean snow pack density. 3. An unresolved, systematic discrepancy exists between the determination of snow water equivalence using the Canadian Snow Sampler and the technique using mean snow depths and mean snow pack density determined from the 100 cc density cutter. 10.2 Quality Assessment 10.2.1 Data Validation by Source Comparison was attempted with HYD-04 snow survey data. Data were similar, but time and location of data collection points were not the same and therefore cannot be directly compared. 10.2.2 Confidence Level/Accuracy Judgment The confidence in snow depth data is a function of the number of measurements made (n) at each site. The more measurements made, the better the variability is represented and therefore the greater the confidence. The snow temperature data are good indications of the temperature gradient at that point. The temperature gradient will vary with snow depth, proximity to a tree, or snow pack base (i.e., forest floor, ice on pond). 10.2.3 Measurement Error for Parameters Snow density measurement accuracy = 5%. 10.2.4 Additional Quality Assessments The data were doublechecked. Calculations were performed at least twice, and more often if a discrepancy existed. 10.2.5 Data Verification by Data Center These data were reviewed to make sure that data were loaded properly. 11. Notes 11.1 Limitations of the Data Snow depth and density and temperatures can be highly variable in forested environments. A single data point cannot accurately represent a forest snow pack. Also, during periods of thaw, the snow pack changes rapidly, and a measurement made on one day may not have much bearing on the snow pack the next day. Note that on 09-Mar-1996 the daily high air temperature reached 0 °C and stayed above freezing for most of the remainder of the field campaign. During this period, the snow pack changed rapidly. 11.2 Known Problems with the Data An unresolved, systematic discrepancy exists between the determination of snow water equivalence using the Canadian Snow Sampler and the technique using mean snow depths and mean snow pack density determined from the 100 cc density cutter. 11.3 Usage Guidance See Section 11.1. 11.4 Other Relevant Information Canadian snow samplers are brittle when very cold, as Piers Sellers found out. 12. Application of the Data Set This data set could be used for a quantitative analysis to compare SWE among different land cover types. The data are also useful for snow modeling purposes or estimating the water potentially available to the soil systems. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description An undetermined spreadsheet software program was used to organize the data. 14.2 Software Access None given. 15. Data Access (This section for BORIS and ORNL DAAC Use) Primary contact: Ms. Beth Nelson BOREAS Data Manager NASA GSFC Greenbelt, MD (301) 286-4005 (301) 286-0239 (fax) beth@ltpmail.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, fax, or personal visit. 15.4 Data Center Status/Plans The HYD-03 snow measurement 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 Contact BORIS staff. 16.2 Film Products Contact BORIS staff. 16.3 Other Products Contact BORIS staff. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Not applicable. 17.2 Journal Articles and Study Reports Davis, R.E., C. Woodcock, and J.P. Hardy. 1996. Toward spatially distributed modeling of snow in the boreal forest. Eos Transactions, AGU 1995 Fall Meeting, Abstract, p. 218. Davis, R.E., J.P. Hardy, W. Ni, C. Woodcock, C.J. McKenzie, R. Jordan, and X. Li. 1997. Variation of snow ablation in the boreal forest: A sensitivity study on the effects of conifer canopy. Journal of Geophysical Research. 102(D24):29389-29396. Hardy, J.P., R.E. Davis, and G.C. Winston. 1995. Evolution of factors affecting gas transmissivity of snow in the boreal forest. In: Biogeochemistry of Seasonally Snow-Covered Catchments (ed. by K. Tonnessen, M.W. Williams, and M. Tranter) (Proc. Boulder Symp., July 1995). IAHS publication no. 228, p. 51- 60. Hardy, J.P., R.E. Davis, and R. Jordan. 1996. Snow melt modeling in the boreal forest. Eos Transactions, AGU 1996 Fall Meeting, abstract, p. 196. Hardy, J.P., R.E. Davis, and J.C. McKenzie. 1995. Snow Distribution Around Trees: Incorporation of snow interception patterns into spatially distributed snow models. Eos Transactions, AGU 1995 Fall Meeting, Abstract, p. 202. Hardy, J.P., R.E. Davis, R. Jordan, X. Li, C. Woodcock, W. Ni, and J.C. McKenzie. 1997. Snow ablation modeling at the stand scale in a boreal jack pine forest. Journal of Geophysical Research. 102(D24): 29397-29406. 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.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, F.E. Guertin. 1997. BOREAS in 1997: Experiment overview, scientific results, and future directions. Journal of Geophysical Research. 102(D24):28731-28770. 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. Winston, G.C., B.B. Stephens, E.T. Sundquist, J.P. Hardy, and R.E. Davis. 1995. Seasonal variability in gas transport through snow in a boreal forest. In: Biogeochemistry of Seasonally Snow-Covered Catchments (ed. by K. Tonnessen, M.W. Williams, and M. Tranter) (Proc. Boulder Symp., July 1995). IAHS publication no. 228, p. 61-70. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms ASCII - American Standard Code for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System cc - cubic centimeters CGR - Certified by Group CPI - Certified by Principal Investigator CPI-??? - CPI but questionable CRREL - Cold Regions Research Engineering Laboratory DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System FFC-T - Focused Field Campaign-Thaw FFC-W - Focused Field Campaign-Winter GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center HYD - Hydrology NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration NSA - BOREAS Northern Study Area OBS - Old Black Spruce OJP - Old Jack Pine ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park PI - Principal Investigator PRE - Preliminary SSA - BOREAS Southern Study Area SWE - Snow Water Equivalent URL - Uniform Resource Locator YBS - Young Black Spruce YJP - Young Jack Pine 20. Document Information 20.1 Document Revision Date Written: 25-Mar-1997 Revised: 20-Mar-1998 20.2 Document Review Date(s) BORIS Review: 12-Mar-1998 Science Review: 15-Jul-1997 20.3 Document ID 20.4 Citation 20.5 Document Curator 20.6 Document URL Keywords SNOW SNOW WATER EQUIVALENT HYD03_Snow_Meas.doc Page 9 of 21 04/17/98