OCTOBER 1997. GULF OF ALASKA: OCEANOGRAPHY & FISHERY

El Niño Induced Ocean Eddies in the Gulf of Alaska by Arne Melsom(1), Harley E. Hurlburt(2), E. Joseph Metzger(2), Steven D. Meyers(3) and James J. O'Brien(3) (1) Department of Geophysics, University of Oslo, P.O. Box 1022, Blindern, N-0315, Oslo, Norway. (2) Naval Research Laboratory, Stennis Space Center, MS, 39529-5004, USA. (3) Center for Ocean-Atmospheric Prediction Studies, The Florida State University, Tallahassee, FL 32306-3041, USA. ABSTRACT: Observations reveal substantial eddy activity in the Gulf of Alaska, with the Sitka eddy being a frequently observed anticyclonic feature near 57 N. A unique high-resolution numerical model that accurately reproduces eddy formation, size, and lifetime is able to duplicate the observations. The decadal simulation allows examination of interannual variations in the eddy activity. Interannual variability in the upper ocean coastal circulation in the Gulf of Alaska is due to the El Nino/Southern Oscillation phenomenon in the tropical Pacific. El Nino events destabilize the Alaska Current, creating multiple strong anticyclonic eddies along the coast. These eddies then slowly propagate into the Gulf of Alaska and live for years. El Viejo (La Nina) events generally suppress eddy formation. This high latitude El Nino phenomena must have a major effect on local fisheries. (Teleconnections may thus be products of past ENSO events, complicating the search for cause and effect--Ed.)

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