Impacts of surface gravity waves on summer ocean dynamics in Bohai Sea

Abstract

A one-way coupled POMgcs-SWAN model is applied to study the impacts of three wave processes, i.e. Langmuir turbulence, Coriolis-Stokes forcing (CSF) and resolved-scale Craik-Leibovich vortex forcing (CLVF), on ocean dynamics in Bohai Sea in summer. Both CSF and CLVF are included in the horizontal momentum equation. The level-2.5 Mellor-Yamada turbulence closure scheme is modified to contain the parameterization of Langmuir turbulence. Numerical results show that this improved model reproduces the sea surface temperature (SST) better than the original one. All of these wave effects considerably contribute to temperature variability at different vertical levels, with the maximum temperature change of about 0.4 °C. Based on the diagnostic experiments, the impacts of the CSF and CLVF are much weaker than that of Langmuir turbulence. Those wave processes reduce the current velocity and make the current more vertically uniform. The horizontal distribution of Langmuir number indicates that the Langmuir turbulence is prevalent in Bohai Sea. The large vertical kinematic viscosity coefficients, containing the Langmuir turbulence, would lead to a strong vertical mixing.