Satellite passive microwave studies of the Sea of Okhotsk ice cover and its relation to oceanic processes, 1978–1982

Abstract

This paper describes the use of the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) satellite data to study the ice cover in the Sea of Okhotsk during the four winters of 1978–1982. The ice concentration estimates obtained from SMMR are used to study two different polynyas: one over the Kashevarova Bank, and the other over the northwest continental shelf. For the Kashevarova polynya this study shows that the polynya, which may be related to the upwelling observed in historic summer cruises, occurs directly over the bank. For the continental shelf, which because of strong offshore winds and cold temperatures is a region of high ice production, the polynya areas are combined with heat flux estimates from weather station data to yield the production rates of ice, salt, and dense shelf water. As a previous study by Kitani (1973) shows, the mixing of this dense shelf water with Pacific water yields a water mass unique to the Okhotsk, which is the layer of cold, low‐salinity intermediate water between depths of 150 and 800 m. From our calculations, we estimate that the dense shelf water is produced at an annual rate of about 0.5 Sv, and that the intermediate water is produced at a rate of 1–2 Sv, which yields a renewal time for this layer of 10–40 years.