ALEUTIAN EDDIES AND THEIR IMPACT ON TEMPERATURE AND DISSOLVED OXYGEN IN THE WESTERN SUBARCTIC PACIFIC

Abstract

Aleutian eddies are anticyclonic vortices on scale of 100–200 kilometers that transport the Alaskan Stream warm water originating in the Gulf of Alaska to the western Subarctic Pacific (WSP). We present an analysis of satellite, Argo floats and ship borne observations of Aleutian eddies, revealing the influence of the wind forcing on the eddy formation and shedding. We demonstrate that the eastern winds promote the Aleutian eddy formation south of Near Islands. Positive (cyclonic) wind stress curl in late fall- winter results in the SSH decrease and the mesoscale cyclones formation at the Aleutian eddy boundaries and thereby leads to the eddy shedding from the Alaskan Stream. An appearance of the Aleutian eddies in the central part of the WSP is accompanied by the deepening of the isopycnals and an increase of the temperature and dissolved oxygen (DO) concentration in 150–400 m layer. The eddies decrease the DO concentration on 26.7σθ and 26.8σθ surfaces in the upper intermediate layer but enrich the 27.0σθ surface by DO. The extent to which eddies modulate the temperature and DO concentration in the WSP is related to the SSH amplitude of eddies.