THE 1992 SUMMER CIRCULATION IN THE NORTHEAST WATER POLYNYA FROM ACOUSTIC DOPPLER CURRENT PROFILER MEASUREMENTS

A July-August 1992 snapshot of the circulation in the Northeast Water Polynya located off the coast of Greenland is presented using data collected with an acoustic Doppler current profiler (ADCP) during the cruise of the USCGC Polar Sea. The data reveal anticyclonic circulation with velocity and transport cores aligned with the local topographic trough. Transport through the trough is between 0.5 and 0.9 Sv. The total ADCP measured velocities are generally less than 10 cm s(-1), but some regions have velocities larger than 20 cm s(-1). The ratio of the average velocity of the upper 100 m to the average velocity below 100 m shows surface layer flows faster by a factor of between 1.2 and 2. This ratio in the ice-free northwest portion of the polynya is smaller (approximate to 1.5) than found over the adjacent continental shelf (approximate to 2.0), indicating smaller vertical shear. The data show northward flow along the coast, supporting the idea that ice carried by this flow is blocked from entering the polynya by a persistent ice wedge to the south that extends from the coast, east over the topographic trough, to a shallow central bank. By blocking ice advecting from the south, the ice wedge enhances the polynya, supporting the idea that the Northeast Water Polynya is a latent heat polynya.