Ice movement and distribution in the Bering Sea from March to June 1974

Ice distribution and motion in the Bering Sea from March to June 1974 were observed by imagery from the NOAA 2 and 3 VHRR (very high resolution radiometer) satellites. The southerly ice edge was nearly constant in position from March to mid-May, when ice disintegration had progressed to a point where the edge was undefined. Ice movement was southerly in response to northerly winds until late April, after which variable ice motion reflected variable winds. The southerly motion created regions of ice divergence south of islands and along east-west trending southern coasts. In some areas such as the Bering Strait, water motion exerted sufficient stress on the ice to balance the wind.stress, resulting in stationary ice or northerly ice motion. The Bering Sea ice cover is conceptualized as northern source and southern sink regions connected by an intermediate zone of southerly ice motion. A mean observed southerly ice motion of 18 cm s−1 requires heat losses for ice formation of the order of 10 g-cal m−2 s−1 or an order of magnitude greater if most ice is assumed to form in divergent areas covered by thin ice or that have open water. These values are in agreement with previous estimates of sea-air heat flux in the Arctic.