Arctic Sea-Ice Conditions in Early Spring Viewed by Satellite^∗

Abstract

A detailed analysis was made of satellite imagery, mainly from the NOAA-VHRR (National Oceanic and Atmospheric Administration-Very High Resolution Radiometer) in the visible and infrared range, to produce maps of mean monthly ice concentration of the western Arctic Ocean for March 1973 and March 1974. Using multi-daily coverage of the satellite, a total of 2552 data points divided into 47 subsections of the Arctic Ocean were analyzed. In both years an average of 75% of usable observations were obtained; the cloudy observations constituted 25%. The highest ice concentrations found in the Beaufort Sea and East Siberian Sea were 85% and 81%, respectively for March 1973. For March 1974, the ice concentration was on an average 10% higher due to a greater frequency of onshore wind components as deduced from 5-day means of surface pressure differences between selected coastal stations of the Beaufort Sea. Areas of low ice concentration were found in parts of the northern Bering Sea, along the northwest coast of Alaska and northwest of Wrangel Island in both years. In 1973 low ice concentrations were also observed north of the New Siberian Islands and west of Banks Island.