Synoptic density and velocity observations of slope waters in the Chukchi and East-Siberian Seas

Synoptic velocity and water mass observations obtained in 1993 provide a snapshot of the circulation over the slope of the Chukchi and East Siberian Seas. We describe flow and density fields between the 100-m and 2000-m isobaths >350 km to the north of Siberia near the date line. Strong property gradients on sloping isopycnal surfaces reflect sharp boundaries between upper and lower halocline, as well as Atlantic layer waters. Concurrent velocity observations from a towed acoustic Doppler current profiler reveal an unexpected, 5-10 cm/s strong generally westward subsurface how between the 200-m and 350-m isobaths. The flow is most intense 50 m to 150 m below the surface and is embedded in a tidal current with amplitudes of similar magnitude. Subtidal velocity and water mass observations from sections 250 km apart suggest a spatially continuous westward slope current. Variability associated with submesoscale vortices is shown by a geostrophically balanced anticyclonic eddy which carries anomalous warm shelf water of Pacific origin. The eddy is nearly spun down: Its Rossby number similar to 0.1 is an order of magnitude smaller than those of eddies observed in the Beaufort Sea.