This data set provides estimates of Arctic sea ice extent and concentration from 1901 to 1956 created from a collection of historic, hand-drawn sea ice charts from the Danish Meteorological Institute (DMI). These were used to create estimates for each summer month from 1901 to 1956 by manual, subjective interpretation of scanned versions of the charts. These estimates, shown in colored-coded fields, are available as image files in JPEG format and as GIS shapefiles.
ICE EXTENTSEA ICE CONCENTRATION
FIELD SURVEYS, GROUND-BASED OBSERVATIONS, SHIPS
1 April 1901 to 31 August 1939
, 1 April 1946 to 31 August 1956