WINTER INTENSIFICATION AND WATER MASS EVOLUTION FROM YEARLONG CURRENTMETERS IN THE NORTHEAST WATER POLYNYA

In the summer of 1992, four current meter moorings were deployed in an d later retrieved from the Northeast Water (NEW) polynya on the East G reenland Shelf by the USCGC Polar Sea. The moorings provided hourly te mperature, salinity and current data for approximately one year. In th e NEW, the circulation intensified and steadiness increased during win ter. This intensification was most readily observed at 150 m on the so uthern side of Westwind trough. The surface layer freshened from summe r through December due to ice-melt and freshwater runoff mixing down t o at least 75 m. From December through early spring, salinity increase d probably due to brine rejected during ice formation. Wintertime even ts showed water at 75 m with temperatures at the freezing point. Knee Water (KW) was not observed in the current meter data. However, a warm er and fresher than KW watermass was observed at 150 m over the shelf and may result from mixing outside the NEW among KW and the major wate r masses influencing the region, Polar Water and Atlantic Intermediate Water. Several short-lived events of 3 to 7 days duration perturbed t he T-S character at each of the current meters. We believe that these T-S shifts were anticyclonic eddies advecting through the NEW polynya. During such perturbations, T-S values found generally at 75 m were ob served at 150 m and T-S values generally at 150 m were observed at 250 m. On the northern side of the Westwind trough, the current meter dat a provided direct evidence for westward flow into the western extent o f the trough at a depth of 250 m. This southwesterly current along the northwest slope of the trough at 250 m is in agreement with the summe rtime ADCP measurements made in 1992 aboard Polar Sea, and is consiste nt with the flow inferred from summer hydrography measured from Polars tern in 1993.