The Impact of the Siberian High and Aleutian Low on the Sea-Ice Cover of the Sea of Okhotsk

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Abstract
Comparison of monthly averaged sea-ice distributions in the Sea of Okhotsk with atmospheric pressure data during the four winters having passive-microwave sea-ice coverage from the Nimbus 5 satellite, 1973–76, revealed a strong apparent relationship between the extent of the sea-ice cover and the influence of the Siberian High atmospheric pressure system. Examination of data for the years 1978–86, having passive-microwave coverage from the Nimbus 7 satellite, reveals that the strong correspondence found for 1973–76 between Okhotsk sea-ice extents and the Siberian High was not maintained in the 1978–86 period. A weaker correspondence continued, however, between the sea ice and the combined Siberian High/Aleutian Low system. A Siberian High/Aleutian Low index was created, and the correlation coefficient between that index and sea-ice extents in the midwinter month of February is 0.97 for the 1973–76 period and 0.52 for the 1978–86 period. Primary reasons for the lack of a consistently strong monthly averaged ice/atmosphere correspondence are: the various oceanographic influences on the sea-ice cover, the failure of monthly averages to reflect fully the important shorter-term interactions between the ice and the atmosphere, and the fact that ice conditions in one month are influenced by ice conditions in previous months.