File Name Convention -------------------- The filenames for the various files in this data set use the following naming convention: modis_xxx_ss_yyyymmdd_BB.asc where, xxx is: bsa: Black_Sky_Albedo wsa: White_Sky_Albedo qa: albedo quality information ss is the spatial resolution: 1d: 1 degree resolution hd: half degree resolution qd: quarter degree resolution YYYYmmdd: Where YYYY is year, mm is month and dd is day for the starting date of the 16-day period of coverage. BB is the spectral band: b1=Albedo for MODIS band 1 (620-670 nm) b2=Albedo for MODIS band 2 (841-876 nm) b3=Albedo for MODIS band 3 (459-479 nm) b4=Albedo for MODIS band 4 (545-565 nm) b5=Albedo for MODIS band 5 (1230-1250 nm) b6=Albedo for MODIS band 6 (1628-1652 nm) b7=Albedo for MODIS band 7 (2105-2155 nm) bb1=MODIS broadband albedo 1 (300-700 nm) bb2=MODIS broadband albedo 2 (700-5000 nm) bb3=MODIS broadband albedo 3 (300-5000 nm) qa1 to qa8: 8 MODIS Albedo Quality layers (see description below) ***NOTE: Layers qa2 and qa3 have been omitted ############################################################################## ASCII File Format ------------------ All of the files in the ISLSCP Initiative II data collection are in the ASCII, or text format. The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. The files at different spatial resolutions each contain the following numbers of column and rows: One degree: 360 columns by 180 rows 1/2 degree: 720 columns by 360 rows 1/4 degree: 1440 columns by 720 rows All values are written as floating point values. Missing values are assigned the value of -88. All files are gridded to a common equal-angle lat/long grid, where the coordinates of the upper left corner of the files are located at 180W, 90N and the lower right corner coordinates are located at 180E, 90S. Data in the files are ordered from North to South and from West to East beginning at 180 degrees West and 90 degrees North. Albedo Files ------------ The multi-spectral albedo files are all stored as real number values from 0 to 1. Albedo Quality Files -------------------- The albedo quality information files are all stored with each pixel written as an integer. Each pixel corresponds to the same pixel in the multi-spectral albedo files for each measurement period. A fill value of -99 is used when no data are given. The descriptions of the values used in the quality layers are given below. 1 Mandatory QA 0 = Majority processed, good quality 1 = Majority processed, see other QA 2 = Majority not processed due to cloud effects 3 = Majority not processed due to other effects 2 Period used 0 = 16 days 1 = 32 days 3 AM/MISR/PM 0 = AM 1 = AM/PM 2 = AM/PM/MISR 3 = AM/MISR 4 = PM 5 = PM/MISR 6 = MISR 4 BRDF Quality 0 = Majority full inversion 1 = Majority magnitude inversion 2 = Majority Bus-in DB parameters (not currently used) 3 = Majority Fill value 5 Percent Land 0-100 6 Percent Snow 0-100 7 Local Solar Noon 0 = 0-5 degrees 1 = 5-10 degrees 2 = 10-15 degrees 3 = 15-20 degrees 4 = 20-25 degrees 5 = 25-30 degrees 6 = 30-35 degrees 7 = 35-40 degrees 8 = 40-45 degrees 9 = 45-50 degrees 10 = 50-55 degrees 11 = 55-60 degrees 12 = 60-65 degrees 13 = 65-70 degrees 14 = 70-75 degrees 15 = >75 degrees 8 Percent 0 = 5% or less data (land) from inputs contributed to this pixel Contribution 1 = 5% - 15% " 2 = 15% - 30% " 3 = 30% - 50% " 4 = 50% - 70% " 5 = 70% - 85% " 6 = 85% - 95% " 7 = 95% or more