Sample AVHRR-based global daily snow fraction maps

size: 9000x4500
grid cell size: 0.04 x 0.04 deg (about 4km)
projection:     latitude-longitude
upper left corner coordinates: 90N 180W
orientation: north to south, west to east 
format:         1-byte binary

Byte values meaning:
   0: water
   1: snow-free land
   5: ice
   6: potential/broken/melting ice
  10: clouds/undetermined over land
  11: clouds/undetermined over water
  101-200: snow fraction in % (SFR+100)

avhrr_4km_lats and avhrr_4km_lons are latitude and longitude files 
size : 9000x4500
format: 4-byte real

Latitude and longitude files give coordinates of the center of each grid cell.