Impact of typhoon Bolaven on coastal wind-driven circulation in Peter the Great Bay
Winds and buoyancy drive the circulation in small bays and estuaries. That circulation controls the exchange with the adjacent waters in deep sea. In bays with complex bathymetry local wind produces downwind flows over shoal and upwind flow in deep channel. Observations with adequate spatial resolution are rarely obtained to resolve the lateral structure of wind-induced exchange flows. The main purpose of this study is to investigate the wind-induced structure of the flow in the Ussuriysky Bay, Sea of Japan, after the impact of typhoon Bolaven (T1215). Strong storm dramatically changed stratification, sea level and mixed layer depth. However, it was found that north wind-induced current speed had the same magnitude as typhoon-induced velocity. The upwelling, observed in the bay, is driven by the meridional pressure gradient generated by the set down of sea level. This upwelling is a major cause of the observed sudden drop of temperature and increase of salinity in the lower layer. An analytical solution of wind-driven flow is applied to the cross-section where the instruments were deployed. The wind-driven circulation consisted of downward flow in the surface layer and upwind flow in the deep channel.