BOREAS RSS-08 IFC-3 ADS-PSII Measurements of BRDF at SSA-OBS and SSA-OA Sites Summary Ground BRDF measurements were acquired by the Remote Sensing Science (RSS)-08 team to aid in the development of advanced spectral vegetation indices. The RSS-08 team measured reflectances at the double-scaffold towers in the Southern Study Area (SSA) Old Black Spruce (OBS) and Old Aspen (OA) sites during IFC-3 in 1994. The RSS-08 team also acquired stereo photography at the SSA-OA, SSA-OJP, and SSA-OBS sites during IFC-3. Contact Information Professor Jan-Peter Muller Dept. of Photogrammetry and Surveying University College London London UK Tel. +44-171-380-7227 Email. jpmuller@ps.ucl.ac.uk Fax +44-171-380-0453 Data Acquisition Methods All measurements were acquired with an ASD-PSII hand-held radiometer, with a 1- degree field of view (FOV) head, calibrated against a halon reflectance panel. The integration time used was 350 ms. The first column in each of the data files is the wavelength, in steps of 1.4449 nm. Subsequent columns are the measured reflectances. The data is stored as American Standard Code for Information Interchange (ASCII) with comma separated fields. SSA-OA (53.629° N, 106.198° W) The height at which the measurements were made was 24 meters, vertical height above the canopy was 3 meters. Each of the four old aspen files contains data collected on 15-Sep-1994 at a view zenith angle of 57 degrees. Each filename gives the view azimuth (vaz), solar zenith angle (sza) and solar azimuth (saz) angles at which the measurements were recorded. SSA-OBS (53.988° N 105.119° W) The height at which the measurements were made was 14.4 meters, vertical height above the canopy was 7.3 meters. The two files contain sets of measurements that were recorded on 17-Sep-1994 at different solar azimuth angles, 170 and 230 degrees. Data File Descriptions: A total of 6 data files were provided (four files for the SSA-OA site and 2 files for the SSA-OBS site). The files are named based on the date when they were collected, the site where they were collected, and the solar azimuth at the time of data collection. The integration time used was 350 ms. The first column in each of the data files is the wavelength, in steps of 1.4449 nm. Subsequent columns are the measured reflectances. Table of parameter values for each of the four SSA-OA files: Date Time Target VZA VAZ SZA SAZ SAZN Sept. 15, 1994 19:03 GMT Old Aspen 057 322 051 140 40 Sept. 15, 1994 19:12 GMT Old Aspen 057 140 051 160 50 Sept. 15, 1994 19:19 GMT Old Aspen 057 225 051 165 40 Sept. 15, 1994 19:27 GMT Old Aspen 057 055 051 172 50 Where: VZA = view zenith angle, VAZ = view azimuth angle, SZA = solar zenith angle, SAZ = solar azimuth angle, SAZN = number of spectra collected. File format Column | Column Number | Contents ---------- |--------------------------------------------------------- 1 | Wavelength (nm) 2 | Reflectance spectrum recorded at first integration. 3 | Reflectance spectrum recorded at second integration. \ \ / / | n | Reflectance spectrum recorded at nth integration. The first set of measurements made were those at the OA site from the flux tower. Instead of integrating a number of spectra, which we did for the other measurements, we used only one spectrum per view angle. There was a breeze blowing during these measurements and this may explain the zeros that appear in the data. These zero values should be treated as NODATA for any subsequent averaging. Table of parameter values for each of the two SSA-OBS files: Date Time Target VZA VAZ SZA SAZ SAZN Sept. 17, 1994 19:00 GMT Black Spruce 000 110 052 170 1 Sept. 17, 1994 19:03 GMT Black Spruce 057 110 052 170 1 Sept. 17, 1994 19:06 GMT Black Spruce 000 200 052 170 1 Sept. 17, 1994 19:08 GMT Black Spruce 057 200 052 170 1 Sept. 17, 1994 19:11 GMT Black Spruce 000 260 052 170 1 Sept. 17, 1994 19:12 GMT Black Spruce 057 260 052 170 1 Sept. 17, 1994 19:15 GMT Black Spruce 000 320 052 170 1 Sept. 17, 1994 19:16 GMT Black Spruce 057 320 052 170 1 Sept. 17, 1994 22:29 GMT Black Spruce 000 110 064 230 1 Sept. 17, 1994 22:31 GMT Black Spruce 057 110 064 230 1 Sept. 17, 1994 22:32 GMT Black Spruce 000 200 064 230 1 Sept. 17, 1994 22:33 GMT Black Spruce 057 200 064 230 1 Sept. 17, 1994 22:34 GMT Black Spruce 000 260 064 230 1 Sept. 17, 1994 22:36 GMT Black Spruce 057 260 064 230 1 Sept. 17, 1994 22:37 GMT Black Spruce 000 320 064 230 1 Sept. 17, 1994 22:38 GMT Black Spruce 057 320 064 230 1 Where: VZA = view zenith angle, VAZ = view azimuth angle, SZA = solar zenith angle, SAZ = solar azimuth angle, SAZN = number of spectra collected. File format Column | Column Number | Contents ---------- |----------------------------------------------------- 1 | wavelength 2 | reflectance at view_zenith_00 view_azimuth_110. 3 | reflectance at view_zenith_57 view_azimuth_110. 4 | reflectance at view_zenith_00 view_azimuth_200. 5 | reflectance at view_zenith_57 view_azimuth_200. 6 | reflectance at view_zenith_00 view_azimuth_260. 7 | reflectance at view_zenith_57 view_azimuth_260. 8 | reflectance at view_zenith_00 view_azimuth_320. 9 | reflectance at view_zenith_57 view_azimuth_320. Data Access 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 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. 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. References 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. Document Information Written: 07-Jul-1995 Revised: 30-Sep-1999 BORIS Review: 29-Sep-1999 RSS08_ASD.doc 09/30/99