Brief description of global multisensor automated snow/ice cover maps 

Global snow and ice cover masp are generated from combined snow/ice retrievals with
several satellite sensors operating in the visible/infrared and in the microwave spectral bands. 

Since 2018 the snow/and ice mapping system processes and uses observations from the following sensors:

METOP-B AVHRR 
DMSP F-15,-16,-17,-18  SSMIS

Map projection: lat-lon
Grid size:   0.04 x 0.04 deg lat,lon
Grid size:  9000 (lon) x 4500 (lat)
Coordinates of the upper left corner of the upper left pixel is 90N, 180W
Orientation: west to east

Files are 1-byte binary (0-255)

Meaning of byte values:

0: ice free water
1: snow free land
2: snow
3: ice
200 and over: undetermined 

Global maps are compressed with linux compress command

File naming convention:

gl_4km_snow_ice_map_2010330

2010 is the year
 330 is the day of the year number

At this point only one file is saved in the archive.

read_global_snow_ice.pro is an IDL code demonstrating how to read the map data and generate a .png image