By using the MHI oceanic model, the upper layer currents, the surface heat and freshwater fluxes, the sea surface temperature (SST) and the sea surface salinity (SSS) are simulated for the Japan Sea. Given atmospheric variables are used for the surface heat and freshwater balance calculation; no restoration condition towards observed SST or SSS is applied. The simulated surface fluxes, SST, and SSS compare well with the long-term data. The simulated freshwater flux is directed from the air to the sea in spring and summer and from the sea to the air in autumn and winter. The simulation results suggest that SSS in the Japan Sea is mostly controlled by the surface freshwater flux and advection through the straits.
Study results show the propagation of near bottom cold onshore currents that followed the internal waves in an area where bottom topography is characterized by gentle slopes. The cold water currents finally penetrated into Shiraho reef area and were found to affect the water circulation pattern and thermal environment significantly around Tooru-guchi region where a big reef gap is located. After cold westward current penetration, a significant temperature fall was observed in the reef area. As cold westward current flowed in the bottom layer, warm currents headed offshore through the surface layer. The characteristic currents and thermal environment of the region are discussed in detail.