Author(s): Thomas L. Kozo; Lenora J. Torgerson
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Keywords: No Keywords
Abstract: Satellite imagery obtained over the Canadian Basin has been meshed with Arctic Ocean Buoy Program (National Science Foundation and the Office of Naval Research) meteorological data for the months of April-May 1982. Atmospheric pressure data from 6 satellite transmitting buoys drifting on the Basin sea ice allowed for better definition of synoptic weather patterns. The April imagery showed a major fracture in the sea ice canopy (over 1000 km long) just west of the Canadian Archipelago. This fracture grew from a lead to a polynya with a maximum width of 80 km from April 27 to May 3 and signaled the onset of major sea ice movement along the Alaskan Beaufort Sea coast to the south. Prefracture drift was 8 km/day for 7 ms-1 surface winds from the east. Postfracture drift was 16 km/day for 7 ms-1 surface winds from the east which compares to summer ice drift under usually unconsolidated conditions. April is a meteorological transition month in which the Siberian high tends to lose its dominance allowing synoptic lows to enter the Canadian Basin with increased frequency. Synoptic lows moved into the Basin, twice in April, spending several days over the typical position of the Beaufort Gyre current system. They were centered on 80° N and 150° W with a counterclockwise rotational sense, opposite to the ice canopy rotation induced by the Gyre. Each low produced geostrophic wind speeds that reached 15 ms-1 with a wind direction that pushed the ice pack toward the Canadian Archipelago. After the low dissipated, a persistent high followed with geostrophic wind speeds of 15 ms-1 and an ice-push direction 180° from that of the previous low. The late April event moved the main ice pack away from the nearshore ice in the Archipelago and resulted in a large lead. Reasons for this extensive fracture in this coastal ice zone are thought to be storm tide cracking and barometric effects, increase in ice divergence due to superposition of the synoptic low over the Beaufort Gyre and the 180° alternation of wind stress application.
Year: 1988