Influence of stratification on residual tidal currents in the Yellow Sea

The M-2 tide and residual current generation in the Yellow Sea are examined using the Blumberg and Mellor [1987] numerical coastal ocean circulation m odel. With no stratification the model tide and tidal currents show good ag reement with the observed tide and tidal currents. Coherent residual curren ts are predicted around the southwest of Korea, flowing northward as a stro ng jet with a maximum speed of 8 cm s(-1), and around Yangtze Bank, flowing southeastward as a weak broad current. With initial stratification, tidal mixing occurs in the bottom boundary layer, which leads to surface tidal fr onts around Yangtze Bank and the southwest of Korea, and our model experime nts reproduce successfully the basic water property structure in these regi ons. The resulting stratified tidal rectification intensifies the residual currents at the front and at the top of the bottom boundary layer over the sloping bottom, so that the vertical structure of the residual currents is modified. The strong residual currents in the top of the bottom mixed layer around Yangtze Bank support the interpretation of Kim et al. [1991] for th e southeastward movement of Yellow Sea Bottom Cold Water in summer. The res idual currents in the surface layer reach similar to 40% of the mean curren ts observed by Beardsley et al. [1992] using satellite-tracked drifters dep loyed in the Yellow Sea in summer. These results suggest that stratified ti dal rectification is an important process in driving the summertime subtida l flow in the Yellow Sea.