Anticyclonic eddy caused by the Soya Warm Current in an Okhotsk OGCM

Abstract

An OGCM of the Sea of Okhotsk with a 1/12° horizontal resolution and 45 vertical levels has been constructed, which successfully represents characteristics of its circulations. This article focuses particularly on an anticyclonic eddy forming off Hokkaido in the OGCM. It forms in late summer when the warm and saline Soya Warm Current Water separates from the northeastern coast of Hokkaido. This eddy is identified as the eddy studied by Wakatsuchi and Martin (1991) since its location, evolution and vertical structure are consistent with their description. Numerical experiments with varying transport of the Soya Warm Current (SWC) have been carried out, where the transport of the SWC is changed by applying the Island Rule around Hokkaido. It is shown that the eddy formation depends on the transport of the SWC. When the transport is large, an eddy forms off the Shiretoko Peninsula. When the transport is small, however, the saline Soya Warm Current Water does not reach that area, nor does a distinct eddy form. It is when the inflow transport of the Soya Warm Current is larger than the outflow from the Nemuro Strait and the Kunashiri Channel that the anticyclonic eddy forms.