Analysis of Wintertime Currents in the Middle of Northern Yellow Sea Based on a Direct Observation

More than one month current and pressure time series were retrieved from a mooring station in the middle of Northern Yellow Sea in the winter of 2006 to investigate ocean’s response to wintertime atmospheric forcing. Significant variations were found in lowpass-filtered (36 hr) currents and sea levels time series, which are associated with winter extratropical storms passing this region.Empirical Orthogonal Function (EOF) analysis reveals two modes of subtidal currents, with one showing a two-layer typical compensation flow pattern and the other a uniform response throughout the entire water column. Specifically for the second mode, the currents reverse their direction within 1~2 days after the strong winds breakout and reached a speed up to 30cm/s. Such intensive inflow/outflow introduced massive water exchange between the marginal seas (Bohai and Yellow Seas) and open ocean, accompanied with a significant sea level change with an order of ~ 1m. A numerical model was then adapted to this region to represent this process and to evaluate their impacts on water exchange and long-term transports, as well as influences on inter-annual variability of the Bohai and Yellow Sea’s regional dynamics.