Sea Ice Drift And Deformation In The Western Arctic

Groups of ARGOS sea ice buoys were deployed in the Bering, Chukchi, and Beaufort seas over a decade. The pattern that emerges shows that Norton Sound and the coastal zone of the Seward Peninsula episodically produce ice that is both exported to the Arctic through Bering Strait and fed to the conveyor belt system of the southem Bering Sea. Additional major ice formation centers for the Bering system are the west coast of Alaska from the Yukon to Nunivak Island during easterly winds and the St. Lawrence Island polynya and Chukotsk Peninsula during northerly winds. Additional ice formation centers for the Chukchi system are the west coast of Alaska during easterly winds and intrusions of ice from the Beaufort coastal zone. There is a net partitioning of the drift in the Chukchi between the Alaskan Coastal Current and the broad flow out Hope Valley toward Wrangel Island. Although the vector mean drift in Bering Strait is northward, the mean is smaller than the currents at depth because of wind reversals and the interannual variability is large. Mesoscale strain was estimated for triplets of ARGOS buoy tracks in the westem Arctic. On the open Bering Shelf tidal energy dominates both the velocity field (20 50 %) and the components of the strain field. Also the M4 tidal component of the ice velocity is about 45% of the amplitude of M,, while M, in the ocean current is about 2%. This partial shift from semi-diurnal (12.4-hr) to 6.2-hour energy is caused by a compressional wave which propagates through the pack at both extremes of the semi-diumal tidal oscillation. Daily gaps in the ARGOS coverage due to the distribution of satellite passes at low polar latitudes can be bridged best by using the tidal information from regional current measurements with appropriately enhanced M, to help generate a synthetic series, rather than least-squares or spline curve fitting techniques.