Guangliang Liu

and 3 more

The nonlinear effect of the summer SE wind and density on the 3D structures of the full Lagrangian residual velocity (LRV) was quantified for a general nonlinear system, using Jiaozhou Bay, China (JZB), as the test site. In the tidally energetic JZB, the basic patterns of the wind- and density-driven full LRV were found to be consistent with simplified semi-analytical solutions but highly dependent on the initial times. The wind-driven full LRVs detected at different tidal phases showed similar laterally sheared, three-layer circulation, but the main branches could migrate across nearly half of the inner bay. The density-driven, clockwise flow dominated the western inner bay at low tide, while almost disappearing at high tide. The effect of density generally enhanced outward flow in the surface layer and inward flow in the bottom layer. Along-trajectory, integrated momentum balances indicated that viscosity was the main force responsible for the time-dependence of the wind-driven full LRV, while viscosity and the barotropic and baroclinic pressure gradients were the main drivers of the intra-tidal variations in the density-driven full LRV. Generally, the summer wind and density had opposing effects, although their influence was weaker than that of the tide and could not change the patterns of the tide-driven full LRV. The results indicated that when the effects of wind and density on the coastal circulation of tidally energetic waters are analysed, both the 3D structures and the possibility of a high initial tidal phase dependency should be considered.