Characteristics of cyclonic and anticyclonic eddies in the southeastern Bering Sea (1998-2000) using TOPEX/POSEIDON

Abstract

During 1998 - 2000, sea surface height anomalies (SSHA) calculated from TOPEX/POSEIDON Merged Geophysical Data Record and The TOPEX/ERS2 SSHA maps (extracted from CCAR web site, http://ccar.colorado.edu/~realtime/bering/) were analyzed to understand the mesoscale eddy field along and across the shelf edge in the southeastern Bering Sea. The trace of the mesoscale eddy using SSHA maps showed the number and the occurrence of the mesoscale eddy. In 1998 to 1999, the number of the mesoscale eddy was low (244 ~ 256) and positive SSHA was prominent along the shelf edge. Especially, the eddy kinetic energy along the shelf edge was quite low inthe summer of 1999. In 2000 and 2001, however, the number of the mesoscale eddy relatively high (312 ~ 324) and the eddy kinetic energy was high in summer. TOPEX/POSEIDON SSHA ground track D-79 implies the change of the variability and the velocity of the positive SSHA field meaning anticyclonic eddy field along the shelf edge from 2000. These results indicate that the variability of the Bering Slope Current flux resulted in the occurrence of the mesoscale eddy field that has an influence on nutrient supply following high chlorophyll α distribution into the euphotic zone along the shelf edge. Mesoscale eddy field in the oceanic region migrated offshore or remained near the shelf break, not moved onto the shelf. A drifting buoy tracking Bering Sea eddies, however, observed the onshelf flow, in 2000. Results indicate that the horizontal mixing of mesoscale eddies along the shelf edge will play an important role in the Shelf-Slope exchange.