Two‐layer tidal modeling of the Yellow and East China Seas with application to seasonal variability of the M₂ tide

Abstract

The baroclinic response of tide and tidal currents in the Yellow and East China Seas is investigated using a two‐layer numerical model. Seasonal variability in the M 2 tide, especially the smaller summer amplitudes prevailing along the Korea/Tsushima Strait [ Kang et al. , 1995 ], is investigated by a series of numerical experiments with varying degrees of stratification specific to winter and summer. Model results show that the summer amplitudes of the M 2 tide around the southwestern tip of the Korean peninsula and Korea/Tsusima Strait decrease, with a peak decrease of about 14 cm off the southwestern tip of the Korean peninsula, while the summer amplitudes in other coastal regions tend to increase. This seasonal variability generally coincides with the observations. These models results indicate that seasonal stratification has several noticeable effects on the tides, including varying degrees of current shear, varying frictional dissipation, and varying barotropic energy flux. In particular, it drives complicated seasonal variability in the M 2 tide, with a peak amplitude modulation of nearly 5% off the southwestern tip of the Korean peninsula. The seasonal variation of barotropic M 2 energy flux through the eastern entrance of the Yellow Sea is thought to induce the corresponding variability in the M 2 amplitude in the Korea/Tsusima Strait, with smaller amplitudes found in the summer.