Interpolated gridded data which have been averaged according to each respective season: 1) The 5 October-November data campaigns correspond to the austral spring, 2) The 3 May-June data campaigns correspond to the austral fall, 3) The 5 February-April campaigns correspond to the austral summer.
 
The 4 columns in the text files correspond to:
Lat, Lon, Sea Ice Freeboard (m), Sea Ice Thickness (m)
Data over land have been set to -999. All other data set to 0.
 
http://neptune.gsfc.nasa.gov/csb/index.php?section=272