The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . easternberings00hood Year: 1981 202 Ice distribution and dynamics In Fig. 12-15, beneath the cloud bands which are aligned approximately parallel to the wind, ice bands are visible with their long axes aligned at approxi- mately right angles to the wind. The bands are 10-13 km long and about km wide at their widest point. For the same day, Gloersen and LaViolette (1974) show the surface pressure map and a Air Force Weather Service Satellite image of the Bering Sea ice. The satell
The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . easternberings00hood Year: 1981 202 Ice distribution and dynamics In Fig. 12-15, beneath the cloud bands which are aligned approximately parallel to the wind, ice bands are visible with their long axes aligned at approxi- mately right angles to the wind. The bands are 10-13 km long and about km wide at their widest point. For the same day, Gloersen and LaViolette (1974) show the surface pressure map and a Air Force Weather Service Satellite image of the Bering Sea ice. The satellite image shows numerous ice bands at the edge; the weather map shows that the winds are ap- proximately from the northeast. Coast Guard weath- er data gathered at the same time (from Campbell et al. 1975) show that the surface air temperature was —10 C and the wind speed was 5 m/sec. How do these bands form? In the previous section, we showed that the effect of wind and waves at the ice edge was to work the ice in the edge zone so that it consists of numerous small floes, heavily rafted and ridged. Therefore the pack ice has an outer band of much thicker ice, with considerable top and bottom topography, adjacent to the open water. We there- fore carried out from the Surveyor a field experiment during a period of off-ice winds to study the move- ment of this thicker edge ice relative to the thinner ice in the transition zone. We found that because of the increased aerodynamic roughness of the ice in the edge zone it moved faster downwind than the interior ice. This relative velocity increase leads to the formation of the observed bands. The experiment On the morning of March 11, after a day of weak easterly winds which compacted the ice edge, we used the helicopter to place six targets on ice floes which were then tracked over a 23-hour period and their position determined from the Global Navigation System (GNS-500A) on the helicopter. Each target consisted of a colored nylon
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