A numerical modeling study for the Japan/East Sea (JES) seasonal circulation and thermohaline structure

Abstract

The seasonal sea circulation and thermohaline structure in the Japan/ East Sea (JES) were studied numerically using the Princeton Ocean Model (POM) with the horizontal resolution varying from 11.54 to 18.53 km and 15 sigma levels conforming to a relatively realistic bottom topography. A twenty four month control run was performed using climatological monthly mean wind stresses and heat and salt fluxes as surface forcing and observational oceanic inflow/ outflow at open boundaries. The seasonally averaged effects of isolated forcing terms are presented and analyzed from the following experiments: (1) non-linear effects removed, (2) no lateral transport at open boundary, and (3) wind effects removed. This procedure allowed analysis of spatial and temporal contributions of the isolated parameter to the general hydrology of the JES and some of its specific features. Major currents are simulated reasonably well compared to the observations. The nonlinear advection does not affect the general circulation pattern evidently, but does affect the formation of the mesoscale eddies, especially the Ulleung Basin (UB) eddy (all seasons) and the Japan Basin (JB) cyclonic gyre (spring). The lateral boundary forcing enhances (weakens) the JES volume transport in the summer (winter). The wind forcing is the most important factor (80%) for the generation of the JB cyclonic gyre. It drives the Liman Current and damps the East Korean Warm Current in the winter, and generates the UB eddy, and eddies along the Japan Coast Current JCC in all seasons. However, it has almost no effect on the JCC for all seasons.