Role of Stokes Drift in Ocean Dynamics Under Typhoon Conditions in the Bohai Sea

The effect of Stokes drift production (SDP), which includes Coriolis-Stokes forcing, Langmuir circulation, and Craik-Leibovich vortexes, on the upper ocean during typhoon passage in the Bohai Sea (BS), China, is investigated by using a coupled wave-current model. The role of SDP in turbulent mixing and the further dynamics during the entire typhoon period are comprehensively studied. Experimental results show that SDP greatly increases turbulent mixing at all depths under typhoon conditions by up to seven times that under normal weather conditions. SDP generally strengthens sea surface cooling by more than 0.4°C, with the maximum reduction in sea surface temperature (SST) at the during-typhoon stage exceeding 2°C, which is approximately seven times larger than that under normal weather conditions. The SDP-induced decrease in current speed can exceed 0.2 ms −1 , and the change in current direction is generally opposite the wind direction. These results suggest that Stokes drift depresses the effect of strong winds on currents by intensifying turbulent mixing. Mixed layer depth (MLD) is distinctly increased by O(1) during typhoons due to SDP and can deepen by more than 5 m. In addition, the continuous effects of SDP on SST, current, and MLD at the after-typhoon stage indicate a hysteretic response between SDP and typhoon actions.