Temporal and spatial variation of shore-fast ice in the Kara Sea

Abstract

The present study of temporal and spatial variations of shore-fast ice in the Kara Sea includes utilization of aircraft observations by the Arctic and Antarctic Research Institute (AARI) from 1953 to 1990, and surface brightness temperature from SSM/I from 1987 to 2001. Analyses of a time series of spatially distributed SSM/I brightness temperatures provide estimates of the shore-fast ice extent. The present work shows spatial distributions of frequencies of shore-fast ice coverage in the Kara Sea for each month, and it gives a time series of its area. The fast ice extent in early spring typically reaches a stable configuration, which falls into one of two different categories (modes) with significantly different area. The smaller of these two modes tends to appear with increased frequency since 1980. This gives, for this period, a negative trend in fast ice area during spring. There is a correlation above 0.5 between the average winter temperature and maximum ice thickness anomalies and fast ice area. Analysis of surface wind data and sea level pressure indicates that wind during winter controls much of the shore-fast ice development. Specially strong westerly and southwesterly winds tend to give a smaller fast ice extent than otherwise. Variations in river discharge tend only to have an observable effect on the ice at the river mouths.