Regional Arctic ice thickness and brine flux from AVHRR

This study demonstrates that Advanced Very High Resolution Radiometer (AVHRR) thermal imagery is useful for studying spatial and temporal variations of thin ice thickness distribution and associated brine flux in the Arctic. The analysis shows that, compared with near-surface air temperatures from drifting buoys and ice stations, the accuracy of surface temperatures from channel 4 is about 0.9{dollar}spcirc{dollar}C for the central Arctic during the cold season. By combining a thermodynamic ice growth model with measurements of surface temperatures from AVHRR, thin ice thickness distributions are estimated in the Beaufort Sea and the northern Greenland Sea during winter 1990/1991. The largest thin ice concentration is found on the continental shelves. The northern Greenland Sea generally has a larger population of thin ice than the Beaufort Sea because of more divergent ice motion. Seasonal variations are detected by AVHRR in both the Beaufort Sea and the northern Greenland Sea; the former shows a larger seasonal amplitude. Ice growth and salt flux from areas of thin ice also show large spatial and temporal variations. The shelves produce the most ice and salt, contributing about 0.12-0.14 Sverdrup of saline water during winter 1990/1991. Several variables and parameterizations introduce a large group of sensitivities to the model. However, comparisons of satellite measurements with those from moored upward looking sonar and with those from an ice-ocean model suggest that AVHRR is capable of resolving the regional and seasonal variations in thin ice to a level of accuracy useful both for establishing a climatology and for testing ice models.