REMOTELY-SENSED AND SIMULATED VARIABILITY OF ARCTIC SEA-ICE CONCENTRATIONS IN RESPONSE TO ATMOSPHERIC SYNOPTIC SYSTEMS

Responses of the Beaufort Sea and Canada Basin ice pack to the passage of synoptic-scale weather systems are studied using Synthetic Apertur e Radar (SAR), Advanced Very High Resolution Radiometer (AVHRR) and Sp ecial Sensor Microwave/Imager (SSM/I) data combined with ice model sim ulations. Changes within the consolidated ice pack are examined in det ail for October 1991. The analysis is then extended to consider genera l conditions from October 1991 to June 1992. The SAR, SSM/I, and model led concentrations concur generally, showing a 1-5 per cent decrease i n ice fraction during the passage of low-pressure systems through the study area. The AVHRR imagery indicates a greater proportion of thin i ce within the pack, but comparable decreases in concentration. While c hanges in SSM/I-derived open-water fractions are similar to changes in the other data sets, the SSM/I data suggest substantial increases in first-year ice concentration, indicative of the formation of refreezin g open water areas. Sensible heat fluxes calculated using open-water a nd ice-type fractions from the SAR and SSM/I imagery point out the sen sitivity of heat transfer estimates to the data types and classificati on method used to derive ice information.