Studies of Antarctic cloud cover variability from 1982 through 1999

Seasonal and interannual variability of cloud cover statistics in the Antarctic region has been studied using NOAA/Advanced Very High Resolution Radiometer (AVHRR) data from 1982 through 1999. The data reveal 92% to 94% cloud cover in the open water areas from the ice edge to 50/spl deg/ S latitude, 67% to 80% cloud cover over sea ice, and 25% to 70% cloud cover over the continental ice sheet with the least cloud cover in the Antarctic plateau. Large seasonality is also observed over ice covered areas with the most persistent clouds occurring during the summer. Year-to-year fluctuations are apparent with 1985 and 1995 having unusually cloudy summers while 1998 had the most cloudy winter. The cloud cover is also shown to be on a decline of as much as -0.50 /spl plusmn/ 0.06%/year over ice sheets at elevations >2000 m. This trend may partly explain the observed cooling in the continent during the last 2 decades.