FILE_USAGE_DAT.TXT

IDL binary .DAT files are available from
http://lasp.colorado.edu/snoedata/download/data/

The layout of these files is identical to the ASCII files. 
Read FILE_USAGE_ASCII.TXT to learn more about the format. 
View FILE_USAGE_L?.JPEG to see the layout visually.

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The following IDL code should properly open and display L4 data:
IDL> OPENR, 1, 'SNOE_l4_geo.dat', /SWAP_IF_LITTLE_ENDIAN
IDL> file = assoc( 1, fltarr( 38, 18 ) )
IDL> d = file[ 9 ]           ; yyyyddd = 1998079, equinox
IDL> lat = d[ 0:36, 17 ]     ; latitude
IDL> alt = d[ 37, 0:16 ]     ; altitude
IDL> dom = d[ 37, 17 ]       ; day of mission
IDL> data = d[ 0:36, 0:16 ]
IDL> tvscl, congrid( rotate( data, 7 ), 640, 512 )

The following IDL code should properly open and display L3 data:
IDL> OPENR, 1, 'SNOE_l3_geo.dat', /SWAP_IF_LITTLE_ENDIAN
IDL> file = assoc( 1, fltarr( 38, 20, 15 ) )
IDL> d = file[ 9 ]           ; yyyyddd = 1998079, equinox
IDL> orb7 = d[ *,*,6 ]       ; get the 7th orbit of the day
IDL> 
IDL> lat = orb7[ 0:36, 17 ]     ; latitude
IDL> lon = orb7[0:36, 18 ]     ; longitude center of bins
IDL> utc = orb7[ 0:36, 19 ]     ; avg time of bins
IDL> 
IDL> alt = orb7[ 37, 0:16 ]     ; altitude
IDL> dom = orb7[ 37, 17 ]       ; day of mission
IDL> ddd = orb7[ 37, 18 ]       ; ddd = 079
IDL> y   = orb7[ 37, 19 ]       ; year = 1998
IDL>
IDL> data = orb7[ 0:36, 0:16 ]
IDL> tvscl, congrid( rotate( data, 7 ), 640, 512 )
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