ANALYSIS OF MERGED SMMR-SSMI TIME-SERIES OF ARCTIC AND ANTARCTIC SEA-ICE PARAMETERS 1978-1995

The most consistent means of investigating the global sea ice cover is by satellite passive microwave sensors, as these are independent of i llumination and cloud cover. The Nimbus 7 Scanning Multichannel. Micro wave Radiometer (SMMR) and the Defense Meteorological Satellite Progra m (DMSP) Special Sensor Microwave Imager (SSMI) provide information on the global sea ice cover from 1978 to present. The two instruments fl ew simultaneously during a 6-week overlap period in July and August 19 87, thus enabling intercomparison of the two sensors. Brightness tempe ratures are corrected for instrument drift and calibration differences in order to produce continuous time series of monthly averaged Arctic and Antarctic sea ice extent and sea ice area through the use of the NOr-wegian Remote Sensing EXperiment (NORSEX) algorithm, which relates brightness temperatures to ice concentration. Statistical analysis on the time series estimates the decreases in Arctic ice extent and ice area to be 4.5% and 5.7%, respectively, during the 16.8-year observati on period. The overall trends established here serve to better define and strengthen earlier assertions of a reduced ice cover, based on ana lysis of SMMR and SSMI data taken separately. These results are consis tent with GCM simulations that suggest retreat of the sea ice cover un der global warming scenarios.