Heat and fresh water transport by eddies into the Gulf of Alaska

Anticyclonic mesoscale eddies form in winter along the continental margin of Canada and Southeast Alaska between the latitudes of 5 IN and 60N and drift westward into the Gulf of Alaska, carrying warmer, fresher water away from the continental inarain. Detailed measurements of temperature and salinity between 1995 and 2001 were examined to determine the amount of heat and fresh water transported seaward by several eddies that formed west of the Queen Charlotte Islands. Eddies formed in a typical winter carry about 30 x 10(18)J of heat into the gulf, which is about 35% to 60% of the heat transported northward each winter along the continental margin toward this region. The observed range of eddy heat transport is 10(19) to 10(20)J. Largest observed eddy heat transport coincided with increased northward heat flow along the continental margin during the El Nino winter of 1997/1998. Fresh-water volume was determined by evaluating, the amount of fresh water required to reduce the salinity from a reference level to that observed in eddies. This volume varied from 0 to 70 km(3), and was largest during the 1997/1998 El Nino winter. Eddies formed in a typical winter transport 50 km(3) of fresh water seaward, which is about 15% of the estimated fresh-water input to the continental margin in winter between the Columbia River and 54N attributed to local runoff, Plus direct rainfall and flow in major rivers. Crown Copyright (c) 2005 Published by Elsevier Ltd. All rights reserved.