ON THE ORIGIN AND EVOLUTION OF SEA-ICE ANOMALIES IN THE BEAUFORT-CHUKCHI SEA

The origin and space-time evolution of Beaufort-Chukchi Sea ice anomal ies are studied using data and a recently developed dynamic-thermodyna mic sea-ice model. First, the relative importance of anomalies of rive r runoff, atmospheric temperature and wind in creating anomalous sea-i ce conditions in the Beaufort-Chukchi Sea is investigated. The results indicate that wind anomalies are the dominant factor responsible for creating interannual variability in the Beaufort-Chukchi Sea ice cover . Temperature anomalies appear to play a major role for longer time sc ale fluctuations, whereas the effects of runoff anomalies are small. T he sea-ice model is then used to track the position of a positive sea- ice anomaly as it is transported by the Beaufort Gyre toward the Trans polar Drift Stream and then exported out of the Arctic Basin into the Greenland Sea via Fram Strait. The model integration shows that sea-ic e anomalies originating in the western Beaufort Sea can survive a few seasonal cycles as they propogate through the Arctic Basin and can acc ount for a notable amount of anomalous ice export into the Greenland S ea. These anomalies, however, represent a small contribution to the fr esh water budget in this area when compared with sea-ice fluctuations generated by interannually varying local winds.