Tidal Effects on Intermediate Waters: A Case Study in the East/Japan Sea

Abstract

Although tides are believed to be the most important source for diapycnal mixing in the ocean, few studies have directly simulated open-ocean circulation including tides. Because the East/Japan Sea (EJS) has been considered to be a "miniature ocean," tidal effects on the intermediate water of the EJS are investigated by using an eddy-resolving ocean general circulation model that can take account of M-2 and K-1 tides as well as oceanic flows. The simulated temperature and salinity in the intermediate layer are significantly improved by including tides. The improvement results from the combined effect of two internal tides. The M-2 internal tide, propagating into the interior of the EJS, enhances vertical mixing and brings watermass characteristics closer to those observed. The K-1 internal tide, trapped along the coast, induces southwestward flow along the Russian coast in the upper layer and thereby enhances the so-called Liman Current, which transports fresh waters with density conducive to the ventilation of intermediate waters in the EJS.