中国近海潮汐余流数值模拟分析OA

[Objective]Tidal residual currents are generated by nonlinear interactions of tidal forces and bottom friction,bathymetry,and Coriolis effects.They have an important effect on sediment transport,pollutant diffusion,and ocean circulation,especially in offshore shallow waters.This study aims to reveal the distribution characteristics of tidal residual currents in the China marginal seas and their contributions to circulation in these seas and to provide a useful reference for the sustainable development of coastal resources and environmental protection.[Methods]A barotropic tidal model was developed based on the Regional Ocean Modeling System(ROMS).The model domain spans 99° E-150° E and 15° S-41° N,covering all the China marginal seas.It features a horizontal resolution of 0.05° and includes 50 sigma layers in the vertical.The model extracted high-resolution bathymetric data from GEBCO and ETOPO1,and tidal forcing was derived from TPXO9.0.Using the current data simulated by the model,this study calculated Euler residual current,Stokes drift and Lagrange residual current in the China marginal seas and analyzed their distribution characteristics.[Results]The results show that tidal residual currents in the China marginal seas are generally much stronger in shallow waters than in deep waters,with particularly strong currents near islands and shoals.In open deep seas,the residual current velocity is minimal,and the flow direction is irregular and chaotic.Tidal residual currents often form small-scale cyclonic or anticyclonic circulations near coastal areas.Stokes drift is primarily shoreward,comparable in magnitude to Euler residual currents in shallow waters,but negligible in deep waters.Lagrangian residual currents exhibit slightly higher velocities than Euler residual currents in shallow regions and are more directed toward the coast,whereas no obvious difference is observed in deep waters.Euler residual currents show anticyclonic patterns in the Bohai Strait,Laizhou Bay,and central Bohai Sea.In the Yellow Sea,multiple small-scale cyclonic or anticyclonic annular residual currents occur near coastal areas.A residual current originating from the Bohai Strait flows southward along the isobaths in the central Yellow Sea and eventually converges with the offshore residual current from the Yangtze River Estuary.In the Taiwan Strait,Euler residual currents mainly flow northeastward,with an anticyclonic circulation surrounding the Taiwan Bank.South of the Taiwan Bank,a strong southwestward current exists along the slope.Two strong residual current zones exist along the isobaths in the southwest of Taiwan Island,flowing northwestward near the shore and southeastward near the sea.The coastal waters of Fujian are also regions of strong Euler residual currents,whereas the southern coast flows northeastward and the northern coast flows southwestward.On the northern continental shelf of the South China Sea,Euler residual currents mainly flow southwestward.The Qiongzhou Strait is a region of strong residual currents flowing westward or southwestward.The Beibu Gulf is dominated by cyclonic Euler residual currents,which flow southward in the southern part and form a strong residual current zone along the isobaths off the eastern coast of Vietnam.The analysis of tidal residual current contributions shows that tidal residual currents greatly influence the circulation in the China marginal seas.Although their contributions are less than 30％in most regions,they become the dominant component of nearshore circulation in certain areas,such as the coastal area off Jiangsu Province.[Conclusion]This study investigates the spatial distribution and characteristics of tidal residual currents in the China marginal seas,emphasizing their variability between shallow and deep waters and their contributions to regional circulation.These findings provide valuable insights into the distribution and dynamics of tidal residual currents,and improve the understanding of tidal processes and their role in regional circulation,serving as a foundation for future studies and practical applications in marine resource management and environmental protection.