A diagnostic study of the Arctic Ocean winter density-driven circulation in 1973–79

Abstract

Diagnostic computations of density-driven circulation for seven winters from 1973 through 1979 were carried out. The only forcing was provided by observed temperature and salinity data collected during onsite Russian winter surveys in 1973–79. Computed circulations from 1973 through 1978 were close to the mean circulation obtained earlier by averaging observed 1973–79 temperature and salinity (Polyakov & Timokhov 1994). The computed 1979 density-driven circulation flowed counter-clockwise to the north of the Laptev Sea. This circulation pattern was caused by an anomalous salinity distribution associated with changes in the atmospheric circulation regime in 1979. Prevailing offshore winds blew fresh water from the Laptev and East Siberian shelves toward Fram Strait. Fresh water was exchanged for saltier intermediate water that upwelled to the surface along the slope. The observed surface salinity anomalies at the continental slope of the Laptev Sea in 1979 increased by several salinity units. One may speculate that the same process may have caused the observed salinification of the Eurasian Basin in the 1990s.