The increased radius of the Aleutian eddies and their long-term evolution

Abstract

The Alaskan Stream south of the Blizhnii Strait disintegrates into mesoscale Aleutian eddies, which provide a westward transport of warm water to the Kamchatka Current and upper Oyashio Current areas. Oceanographic observations from 1949 to 2009 are indicative of a substantial rise of temperature and salinity in the intermediate waters of the Aleutian and Kamchatka currents. A long-term temperature trend in the Aleutian Current in the intermediate layer (at isopicnal of 26.75s q ) amounted to DT = 0.013°C/year. A positive salinity trend was about 0.0014 psu/year. The ocean upperlayer salinity decreased with a rate of -0.0021 psu/year simultaneously with the increase in salinity of the intermediate layer. The decreased salinity of the upper layer and its increase in the intermediate layer result in the intensified halocline. The radius of the Aleutian eddies significantly increased (by 50-100%), which is equivalent, at least, to twofold increase in the volume of the water transported.

Influences of mesoscale anticyclonic eddies on the zooplankton community south of the western Aleutian Islands during the summer of 2010

“…The Alaskan Stream eddies usually move westward for 1 -5 years and sometimes cross the 1808 meridian and reach the Western Subarctic Gyre. Mesoscale anticyclonic eddies also form in the western Alaskan Stream region (Rogachev et al, 2007;Rogachev and Shlyk, 2009). These eddies form in the region between the 1808 meridian and Near Strait (about 1708E) and are called Aleutian eddies.…”