FY 1982

A climatology of the Bering Sea and its relation to sea ice extent

Pease, C.H., S.A. Schoenberg, and J.E. Overland

NOAA Tech. Report ERL 419-PMEL 36, NTIS: PB82-246950, 29 pp (1982)

The relation between interannual variations in maximum sea ice extent and atmospheric forcing within the region of the Bering Sea is discussed. Monthly maximum sea ice extents for February and March along a line from Norton Sound southwest toward the ice edge are computed for the ice years 1955/56 to 1979/80 and analyzed for each month's average and each year's seasonal maximum ice extent. A storm track climatology is developed by computing monthly cyclone frequencies for each 2°-latitude by 4°-longitude quadrangle within 51°N–65°N, 157°W–171°E from November 1957 through March 1980. Five-day block-averaged sea level pressure fields are analyzed from 1954/55 through 1976/77 by month and year for mean sea level pressure and pressure variance climatologies. The annual winter cycle of the storm count maxima, mean pressure minima, and variance maxima resemble each other closely. The interannual variability of maximum sea ice extent is related to the storm track, mean sea level pressure, and pressure variance climatologies, indicating that in years of greatest ice extent, fewer storms enter the region, and low-pressure centers are quasi-stationary in the western Gulf of Alaska and southeastern Bering Sea. Years of least ice extent are characterized by more storms penetrating the region, particularly in the western sector, and by a larger variance in atmospheric pressure everywhere. Meteorological steering of cyclones, determined primarily externally to the Bering Sea, is indicated as the principal factor causing the interannual variability of sea ice extent.