The Increased Radius of the Aleutian Eddies and Their Long-term Evolution

K. A. Rogachev and N. V. Shlyk

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 26.75) amounted to T = 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.

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