BOREAS RSS-19 1994 Seasonal Understory Reflectance Data Summary One objective of BOREAS is to further the understanding of the spectral bidirectional reflectance of typical boreal ecosystem stands in the visible/near-infrared regime. An essential input for any canopy BRDF model is an accurate estimate of the average understory reflectance, both for sunlit and shaded conditions. These variables can be expected to vary seasonally because of species-dependent differences in the phenological cycle of foliar display. In response to these requirements, the average understory reflectance for the flux tower sites of both the NSA (Thompson, Manitoba) and the SSA (Candle Lake, Saskatchewan) Study Areas (NSA and SSA) was observed throughout the year during five field campaigns. This was done by measuring the nadir reflectance (400 to 850 nm) of sunlit and shaded understory (vegetation and snow cover) along a surveyed LAI transect line (Chen, RSS-07) at each site near solar noon and documenting a average site reflectance. Comparisons between sites reveal differences in the green and infrared regions of the spectra, because of the differing species in the understory for each site. Temporal (seasonal) variation for each site was also observed, indicating the changing flora mixtures and changing spectral signatures as the understory matures during the growing season. 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 RSS-19 1994 Seasonal Understory Reflectance Data 1.2 Data Set Introduction Mean sunlit nadir understory reflectance spectra (400 to 850 nm) and their standard errors for the following canopy types are presented: Fen, Old Black Spruce (OBS), Old Jack Pine (OJP), and Young Jack Pine (YJP). Data for the tower flux sites are provided for both Northern Study Area (NSA) and Southern Study Area (SSA) locations for all five BOReal Ecosystem-Atmosphere Study (BOREAS) field campaigns. These five field campaigns are referred to as Focused Field Campaign-Winter (FFC-W) (Feb. 1994), FFC-Thaw (T) (Apr. 1994), Intensive Field Campaign (IFC)-1 (May/June 1994), IFC-2 (July 1994), and IFC-3 (Sept. 1994). 1.3 Objective/Purpose The objective was to characterize seasonal change in the understory spectral reflectance at eight BOREAS tower flux sites, from February to September, for all five BOREAS field campaigns. 1.4 Summary of Parameters Each data file contains about 20 records of header information, such as: Field Instrument, Reference Calibration Panel, Spectral Range, Wavelength Step, Spectrum Description, Field Of View (FOV), Field Campaign, Location, Latitude, Longitude, Date, Time, Solar Zenith Angle (SZA), Solar Azimuth, Illumination, Target Description, and Comments. After the header information, there are reflectance and standard error measurements for each cover type in the file (one to three) given at each wavelength step within the spectral range. This list is often about 150 records for the Spectron Engineering spectroradiometer (SE)-590, and 378 records for the Analytic Spectral Devices, Inc. (ASD) instrument. 1.5 Discussion Mean sunlit nadir understory reflectance was determined by taking measurements at various points along a surveyed Leaf Area Index (LAI) transect [Chen, 1994], each observation target being chosen as representative of the local area, converting to reflectance, and producing a mean from all the derived reflectances along the transect line [White et al., 1995]. This provided mean understory reflectance, weighted by the component vegetation in the understory throughout the canopy site. BOREAS sites have shown a definite and observable variation in the sunlit mean understory reflectance coefficients in the visible/near-infrared regions as a function of forest species stand. This can be related to change in vegetation in the understory, as well as the difference in growing conditions at each site. Phenological changes are also clearly observable, especially in the case of OBS, indicating the influence of changes in coverage of species type and growth on the nadir reflectance spectrum. 1.6 Related Data Sets BOREAS RSS-01 PARABOLA SSA Surface Reflectance and Transmittance Data BOREAS RSS-03 Reflectance Measured from a Helicopter-Mounted Barnes MMR BOREAS RSS-03 Reflectance Measured from a Helicopter-Mounted SE-590 2. INVESTIGATORS 2.1 Investigators Name and Title John R. Miller (RSS-19), Professor, York University H. Peter White (RSS-19), York University Jim Freemantle (RSS-19), Institute for Space and Terrestrial Science (ISTS) Greg McDermid (RSS-19), University of Waterloo, ISTS Derek R. Peddle(RSS-19), University of Waterloo, ISTS Irene Rubinstein (RSS-19), ISTS Paul Shepherd (RSS-19), ISTS Raymond Soffer (RSS-19), York University Jing Chen (RSS-07), Canada Centre for Remote Sensing (CCRS) Richard Fournier (RSS-19 and TE-09), Universite Laval 2.2 Title of Investigation Seasonal Change in Mean Understory Reflectance for Conifer Flux Tower Sites at BOREAS 2.3 Contact Information Contact 1 ------------------------------------ John R. Miller (RSS-19) Dept. Physics & Astronomy York University North York, Ontario, Canada (416) 736-2100 (416) 736-5626 (fax) miller@eol.ists.ca http://eol.ists.ca Contact 2 ------------------------------------ H. Peter White Dept. Physics & Astronomy York University North York, Ontario, Canada (416) 736-2100 (416) 736-5626 (fax) white@eol.ists.ca http://eol.ists.ca Contact 3 ------------- Jaime Nickeson BORIS Team Representative NASA Goddard Space Flight Center Greenbelt, Maryland Telephone: 301-286-3373 Fax: 301-286-0239 Email: jaime@ltpmail.gsfc.nasa.gov 3. Theory of Measurements An estimate of the average spectral reflectance of the understory for each IFC was made in order to specify the boundary condition in canopy reflectance modeling for Remote Sensing Science (RSS) investigators. The experimental design was focused on (i) determination of an appropriate method of spatial averaging, (ii) characterization of the spectral reflectance of the understory under direct Sun (Sun fleck) and shadow illumination conditions, and (iii) observations within 2 hours of local solar noon to generate measurements of the understory reflectance factor that is representative of remote sensing observations. Observations of 5 to 40 individual spectra at each flux tower site, converted to reflectance by comparison to calibrated reference target, produced a mean reflectance along the transect line [White et al., 1995], considered to be representative of the understory at the date of the measurement. 4. Equipment 4.1 Sensor/Instrument Description Observations were made with the SE-590 field-portable data-logging spectroradiometer except during IFC-1 and some sites during IFC-3, where additional observations were obtained with the ASD instrument. The two instruments used during these campaigns were detector array field spectrometers with spectral ranges nominally 350-1100 nm but with data reported in the 400 to 900 nm range. The calibration panels used in the field were the white and gray side of a Kodak Gray Card (KGW-W and KGC-G respectively), which were spectrally and angularly calibrated at ISTS (Soffer et al. 1995). 4.1.1 Collection Environment The understory conditions at the time of observations as indicated in Section 7.2.2, Table 1, are: Sun - target illuminated by unobscured direct Sun (in a Sun fleck), Shade - target outside of a Sun fleck area illuminated only by diffuse, undercanopy radiation, (s) - snow was observed, (v) - vegetation observed. Observations were made under clear sky conditions or with minimal cloud cover, and in this case without clouds within 60 degrees of the Sun. Observations were made within 2 hours of local solar noon. The ambient air temperature range during observations varied from -35 °C during FFC-W to more than +25 °C in IFC- 2. 4.1.2 Source/Platform SE-590. ASD field spectroradiometer. Both instruments were hand-held by the observer during measurements. 4.1.3 Source/Platform Mission Objectives An estimate of the average spectral reflectance of the understory for each IFC was made in order to specify the boundary condition in canopy reflectance modeling for RSS investigators. 4.1.4 Key Variables Spectral reflectance. 4.1.5 Principles of Operation A nadir-viewing field spectrometer was used to measure the sunlit and shaded (where possible) understory reflectance at marked 10-m-interval transect lines, At each marker location an understory observation target was chosen as representative of the local area. The observations were made in the nadir position, with care to minimize spectral contamination from observers and equipment. The light source for all observations was natural illumination generated by solar direct/diffuse radiation that reaches the forest stand floor. 4.1.6 Sensor/Instrument Measurement Geometry The sensor was kept in a nadir viewing position for all measurements. The height of the instrument was approximately 1 m, translating to an FOV with about a 5-6 m radius. 4.1.7 Manufacturer of Sensor/Instrument The SE-590 was manufactured by: Spectron Engineering, Inc. 225 Yuma Court Denver, CO 80223 USA The ASD field spectroradiometer was manufactured by: Analytic Spectral Devices, Inc. 4760 Walnut Street Suite 105 Boulder, CO 80301 USA. Kodak, of Rochester, NY, manufactures the reference reflectance card. 4.2 Calibration All calibrations of the instruments and the reflecting panels were performed at ISTS using standard laboratory methods. Special care was taken to establish the calibration and estimates of reliability for the Kodak reference cards (KGCs) which were selected for use in the field because of their portability in a relatively difficult field environment and their reported (Milton, 1989). Laboratory bidirectional reflectance measurements were made between 15 and 80 degrees at 5-degree intervals for all six KGCs used in the BOREAS field campaigns. Absolute variability in the reflectance was less than 2% for the white cards and less than 1% for the gray cards, for the entire range of view angles. Data were gathered with a fiber Ocean Optics array-spectrometer mounted on a goniometer and comparisons were made to a Spectralon calibration panel (Labsphere) to obtain absolute panel bidirectional reflectance distribution functions (BRDFs). For validation of ISTS calibration methodology, York University's white Spectralon panel (Labsphere SN 3484 99%) and gray Spectralon panel (Labsphere SN 9485A 50%) were shipped to Dr. Elizabeth Walter-Shea (TE-12) for BOREAS panel field intercalibrations at the University of Nebraska. Comparisons between the Spectralon panel BRDF calibrations for view angles between 15 and 75 degrees were found to be within 2% for the white panel and within 1% for the gray panel. The calibration procedures and results are described in more detail in Soffer et al. [1995]. 4.2.1 Specifications None given. 4.2.1.1 Tolerance None given. 4.2.2 Frequency of Calibration BRDF calibrations of the York University Spectralon panels was carried out prior to IFC-1 (1994), and comparative measurements were made between this Spectralon (white) and KGCs in the field at BOREAS on at least one occasion during each campaign. The detailed BRDF characterization of six KGCs was carried out at ISTS after IFC-3. However, the consistency (<2% for white, <1% for gray) of results between KGCs used at BOREAS and fresh, unused cards indicates insignificant panel deterioration during the campaigns. 4.2.3 Other Calibration Information None given. 5. Data Acquisition Methods A nadir-viewing field spectrometer was used to measure the sunlit and shaded (where possible) understory reflectance at marked 10-m intervals along the surveyed LAI transect line [Chen, 1994], which normally ran in a southeastern direction from each site tower. At each marker location, an understory observation target was chosen as representative of the local area. The observations were made in the nadir position, with care to minimize spectral contamination from observers and equipment. The FOV used allowed for an approximately 5-cm-radius area of understory to be observed, which was followed with a calibration panel observation taken within 1 minute of the target measurement. The calibration panel used, was dependent on the conditions and availability during each campaign. The above methodology was followed closely for all but one field campaign, IFC- 2. During IFC-2, field observations were obtained for species-specific reflectances accompanied by aerial coverage estimates of the species, thereby allowing weighted-average understory reflectance spectra to be determined. Each location was observed with the objective of viewing the average understory composition. When more than one type of understory species mixing occurred at a marker, observations of each flora distribution were performed. Thus, when averaged together, a mean understory reflectance weighted to each type of understory component population was possible. In some cases, sites were divided specifically into small grids, with each grid being observed to provide a detailed understory BRDF for unique locations within the flux tower site, and where possible, observation runs were performed to correspond to Compact Airborne Spectrographic Imager (CASI) multiangle, multialtitude observations also being performed. 6. Observations 6.1 Data Notes None given. 6.2 Field Notes At some sites it was not possible to place the calibration panel level in the exact location of the target being observed. Every effort was made to keep the panel level to the horizon and as close as possible to the target location. It was sometimes necessary to raise the calibration panel above the understory to avoid contamination or destruction, which caused the incident irradiance field to be slightly different between panel and target observations, because of scattering, etc., in the overstory. Such location discrepancies were kept at a minimum, and are not believed to have influenced the results significantly. 7. Data Description A summary of the complete understory data set is provided below in tabular form. This summarizes what data are available by specifying, for each data set, the field campaign, the study area, the flux tower site, the instrument used for the measurements, the type of Kodak reference cards used for in-field reflectance determination, the observation date, and comments regarding the illumination conditions or the understory targets. More detailed information is provided in the spectral data headers. 7.1 Spatial Characteristics Nadir-viewing spectrometer readings were made of the understory at marked 10-m intervals along the surveyed LAI transect line [White et al., 1995]. Also, see Chen et al, 1997, for graphics and details about the layout of LAI transects. 7.1.1 Spatial Coverage Flux Tower Sites -------------------------------------------------------------------------- Site Grid Id Longitude Latitude UTM UTM UTM Easting Northing Zone -------------------------------------------------------------------------- Southern Study Area: SSA-FEN F0L9T 104.61798W 53.80206N 525159.8 5961566.6 13 SSA-OBS G8I4T 105.11779W 53.98717N 492276.5 5982100.5 13 SSA-OJP G2L3T 104.69203W 53.91634N 520227.7 5974257.5 13 SSA-YJP F8L6T 104.64529W 53.87581N 523320.2 5969762.5 13 -------------------------------------------------------------------------- Northern Study Area: NSA-OBS T3R8T 98.48139W 55.88007N 532444.5 6192853.4 14 NSA-OJP T7Q8T 98.62396W 55.92842N 523496.2 6198176.3 14 NSA-YJP T8S9T 98.28706W 55.89575N 544583.9 6194706.9 14 NSA-FEN T7S1T 98.42072W 55.91481N 536207.9 6196749.6 14 -------------------------------------------------------------------------- Each flux tower site allowed for 5 to 40 individual spectral observations. 7.1.2 Spatial Coverage Map Not available. 7.1.3 Spatial Resolution Observations were recorded along a transect line at marked 10 m intervals. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Observations were made during all five BOREAS field campaigns: FFC-W, FFC-T, IFC-1, IFC-2, and IFC-3. Measurements were obtained within 2 hours of local solar noon. 7.2.2 Temporal Coverage Map Field Study Instr. Panel Observation Campaign Area Site Used Used Date Comments --------- ----- ---- ------ ------ ----------- -------------- FFC-W NSA Fen SE590 KGC-W 12-Feb-94 Sun/Debris OJP SE590 KGC-W 12-Feb-94 Sun/Shade YJP SE590 KGC-W 12-Feb-94 Sun/Shade SSA Fen SE590 KGC-W 09-Feb-94 Sun OBS SE590 KGC-W 08-Feb-94 Sun/Shade OJP SE590 KGC-W 06-Feb-94 Sun/shade YJP SE590 KGC-W 09-Feb-94 Sun/Shade FFC-T NSA Fen ASD KGC-W 21-Apr-94 Sun(s,v) OJP ASD KGC-W 21-Apr-94 Sun/Shade(s) SSA OBS ASD KGC-W 16-Apr-94 Sun/Shade(s,v) OJP ASD KGC-W 17-Apr-94 Sun/Shade(v) YJP ASD KGC-W 27-Apr-94 Sun/Shade(s,v) IFC-1 NSA OJP SE590 KGC-W 11(13)-Jun-94 Sun/Shade SSA OBS SE590 KGC-W 31-May-94 Sun/Shade OJP SE590 KGC-W 26-May-94 Sun/shade YJP SE590 KGC-W 26-May-94 Sun/Shade IFC-2 NSA OBS SE590 KGC-W 16-Jul-94 Sun/Shade SSA OBS SE590 KGC-W 23-Jul-94 Sun/Shade OJP SE590 KGC-W 21-Jul-94 Sun/Shade YJP SE590 KGC-W 20-Jul-94 Sun/Shade IFC-3 NSA Fen SE590 KGC-G 03-Sep-94 Sun OBS SE590 KGC-G 02-Sep-94 Sun/Shade OJP SE590 KGC-G 06(07)-Sep-94 Sun/Shade YJP SE590 KGC-G 01-Sep-94 Sun/Shade SSA Fen SE590 KGC-G 12-Sep-94 Sun/Shade OBS SE590 KGC-G 13-Sep-94 Sun/Shade OJP SE590 KGC-G 12-Sep-94 Sun/Shade YJP SE590 KGC-G 12(13)(16)- Sun/Shade Sep-94 7.2.3 Temporal Resolution Observations were made only once at each tower site during each field campaign. For any such flux tower site, measurements were made at 10 to 40 individual understory locations along the 100- to 300-m LAI line within a 30- to 60-minute period near solar noon, in order to minimize changes in the SZA. From these data a mean mid-day understory reflectance was calculated. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (und_refl.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (und_refl.def). 8. DATA ORGANIZATION 8.1 Data Granularity All of the 1994 Seasonal Understory Reflectance 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 a single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition files (und_refl.def). 9. Data Manipulations 9.1 Formulae As described more fully in Peddle et al. (1995), for any particular SZA, the target reflectance is calculated from: target_ref. = (target_signal/reference_panel_signal)*panel_reflectance_at_SZA. The panel reflectance at SZA is calculated by interpolation between laboratory panel BRDF calibrations (Soever et al., 1995). The SZA is calculated from the local time and site longitude and latitude using standard ephemeris equations (see Peddle et al., 1995). 9.1.1 Derivation Techniques and Algorithms It was possible to determine the SZA of each observation to a high degree of accuracy (within a few minutes of arc) using the tower flux site's latitude and longitude outlined in the BOREAS Experiment Plan Ver. 3.0, and the Local Standard Time (LST) of each observation [Observers Handbook, 1994]. A fourth- order polynomial was fitted to the calibration panel BRDF data provided in Soffer et al. [1995] for each SZA and spectrally interpolated [Peddle et al., 1995]. This permitted the understory radiance spectra to be converted to nadir- view reflectance. In the data reduction, no adjustments were made for the difference in SZA between the panel and target measurements, since they were usually taken within 1 minute of each other. 9.2 Data Processing Sequence 9.2.1 Processing Steps The processing steps to convert raw field spectrometer output spectrum to a reflectance spectrum are described above and in detail in Peddle et al. (1995). Subsequently, the observations under direct Sun illumination, for one flux tower site, during one field campaign, were simply averaged (no weighting) to provide the mean understory reflectance. The standard error was also computed as the standard error of the mean (SE), which is related to the standard deviation (SD) by: SE = SD/vN. 9.2.2 Processing Changes All reported data were collected and processed in the same way, except for IFC- 1. In this case, data collection followed a modified strategy in which at each site reflectance spectra were determined for different understory vegetation types (e.g., for lichen, for moss, for labrador tea, etc.), and the aerial coverage of each vegetation type was estimated by site spatial sampling. In this case, the mean understory spectrum was calculated by weighting the reflectance of each understory type by the corresponding aerial coverage. 9.3 Calculations 9.3.1 Special Corrections/Adjustments None. 9.3.2 Calculated Variables Standard error. 9.4 Graphs and Plots Summary graphs of understory reflectances are available from a paper submitted to the JGR special issue Miller et al., 1997). 10. ERRORS 10.1 Sources of Error Although the data were collected between 350-1100 nm, noise due to low signal levels and low detector efficiency in the regions below 400 nm and above 850 nm were observed from both spectrometers and are not presented here. 10.2 Quality Assessment Error estimate curves for the understory reflectance are provided by showing the mean reflectance curve +/- one standard error. 10.2.1 Data Validation by Source Data validation efforts included comparisons with reflectance measurements made by Laval University scientists (unpublished) and comparisons of mean reflectance spectra for one tower site for successive field campaigns, both of which demonstrate consistent results. 10.2.2 Confidence Level/Accuracy Judgment The seasonal variation in the tower site understory reflectances, the between- site variations as reported in the JGR paper (Miller et al., 1997), and the reported standard errors for the spectra reported all suggest data of high quality. 10.2.3 Measurement Error for Parameters Standard error spectra are provided along with the reflectance spectra. 10.2.4 Additional Quality Assessments Visual review of plots and the standard error curves were used to assess data quality and to correct occasional recording errors. 10.2.5 Data Verification by Data Center BOREAS Information System (BORIS) staff have looked at the data and plotted the spectra for all files. 11. Notes 11.1 Limitations of the Data There were some data gaps due to various weather and scheduling difficulties in the field. Calibrations of the panels used in the near-infrared region have not yet been completed. 11.2 Known Problems with the Data None. 11.3 Usage Guidance Although understory reflectance characterization on a species basis may be of interest to some BOREAS scientists, it was not pursued in this study because it would have required a substantially different measurement strategy. Furthermore, a characterization of the complete BRDF of the understory was considered outside the scope of this study. 11.4 Other Relevant Information None given. 12. Application of the Data Set The application of this data set is to estimate the average spectral reflectance of the understory in order to specify the boundary condition in canopy reflectance modeling for each season. 13. FUTURE MODIFICATIONS AND PLANS None. 14. Software 14.1 Software Description In-house macros were written for Microsoft Excel that ingested spectrometer spectral scans for the target and the reference panel, applied corrections for the panel BRDF according to the local SZA, calculated the sample nadir reflectance and then the site-average reflectance spectrum and standard error. See Peddle et al. (1995) for a software and processing description. 14.2 Software Access Because raw data files were not submitted, it is not useful to provide access to the processing software. These data were collected specifically to generate site-average understory spectra. 15. Data Access 15.1 Contact Information Ms. Beth Nelson BOREAS Data Manager NASA GSFC Greenbelt, MD (301) 286-4005 (301) 286-0239 (fax) beth@ltpmail.gsfc.nasa.gov 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 As the BOREAS data are processed and sufficiently quality checked, they will be 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 Oak Ridge, TN (423) 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 The data are available as tabular ASCII files. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation ASD Personal Spectrometer II Reference Manual. 1993. Analytic Spectral Devices Inc., Boulder, Colorado, USA. SE-590 Field-Portable Data-logging Spectroradiometer Operating Manual. Spectron Engineering, Inc., 225 Yuma Court, Denver, Co., 80223, USA. 17.2 Journal Articles and Study Reports Chen, J. and J. Cihlar. 1994. Canadian Centre for Remote Sensing, Private Communication. Chen, J.M., P.M. Rich, S.T. Gower, J.M. Norman, and S.Plummer. 1997. Leaf Area Index of Boreal Forests: Theory, techniques, and measurements. Journal of Geophysical Research, BOREAS Special Issue, 102, 29429-29443. Miller, J.R., H.P. White, J.M. Chen, D.R. Peddle, G. McDermid, R.A. Fournier, P. Shepherd, I. Rubinstein, J. Freemantle, R. Soffer, and E. LeDrew. 1997. Seasonal Change in Understory Reflectance of Boreal Forests and Influence on Canopy Vegetation Indices, Journal of Geophysical Research, BOREAS Special Issue, 102. Milton, E.J. 1989. On the suitability of Kodak neutral test cards as reflectance standards. International Journal of Remote Sensing, Vol. 10. Observer's Handbook 1994. Editor: Roy l. Bishop, The Royal Astronomical Society of Canada. Peddle, D.R., H.P. White, R.J. Soffer, J.R. Miller, and E.F. LeDrew. 1995. Reflectance Processing of Field Spectrometer Data in BOREAS. Proceedings: 17th Canadian Symposium on Remote Sensing, pp. 189-194, Saskatoon, Sask.. 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.and F. Hall. 1997. BOREAS Overview Paper. JGR Special Issue. Soffer, R.J., J.W. Harron, J.R. Miller. 1995. Characterization of Kodak Grey Cards as Reflectance Reference Panels in Support of BOREAS Field Activities. Proceedings: 17th Canadian Symposium on Remote Sensing, pp. 357-362, Saskatoon, Sask. White, H.P., J.R. Miller, J. Chen, D.R. Peddle. 1995. Seasonal Change in Mean Understory Reflectance for BOREAS Sites: Preliminary Results., Proceedings: 17th Canadian Symposium on Remote Sensing, pp. 182-187, Saskatoon, Sask. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms ASCII - American Standard Code for Information Interchange ASD - Analytic Spectral Devices, Inc. personal field spectrometer BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System BRDF - Bidirectional Reflectance Distribution Function CASI - Compact Airborne Spectrographic Imager CCRS - Canada Centre for Remote Sensing 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 FOV - Field of View IFC - Intensive Field Campaign ISTS - Institute for Space and Terrestrial Science KGC - Kodak Grey Card NASA - National Aeronautics and Space Administration NSA - Northern Study Area OBS - Old Black Spruce OJP - Old Jack Pine ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park RSS - Remote Sensing Science SE-590 - Spectron Engineering field spectroradiometer SSA - Southern Study Area SZA - Solar Zenith Angle TE - Terrestrial Ecology URL - Uniform Resource Locator 20. Document Information 20.1 Document Revision Date Written: 07-Jan-1997 Last updated: 04-Jun-1998 20.2 Document Review Date(s) BORIS Review: 26-May-1998 Science Review: 03-Jan-1998 20.3 Document ID 20.4 Citation If this data set is referenced by another investigator, please acknowledge the paper by Miller et al., (1997), listed in Section 17. 20.5 Document Curator 20.6 Document URL Keywords: BRDF Reflectance Spectroradiometer RSS19_Undstry_refl.doc 06/11/98