A numerical study of wave-current interaction through surface and bottom stresses: Wind-driven circulation in the South Atlantic Bight under uniform winds

The influences of surface waves on ocean currents in the coastal waters of the South Atlantic Bight are investigated by using a coupled wave-current modeling system. The ocean circulation model employed is the three-dimensional Princeton Ocean Model (POM), and the wave model invoked is an improved third-generation wave model (WAM). The coupling procedure between the POM and the WAM and the simulated coastal ocean circulation driven by uniform surface winds are presented. The simulated results show that wind waves can significantly affect coastal ocean currents not only through an enhancement of wind stress but also through a modification of bottom stress. Wave-induced wind stress increases the magnitude of currents both at the surface and near the seabed. On the other hand, wave-induced bottom stress weakens the currents both at the sea surface and near the seabed. Therefore the net effect of surface wind waves on currents depends on the relative importance of current modulations by wave-induced wind stress and bottom stress. The results further indicate that at a fixed location, the relative importance of wave-induced surface and bottom shear stresses in coastal ocean circulation depends on the surface wind field. For the constant wind cases considered in this study, the effect of wave-induced bottom stress is more significant in along-shore wind conditions than in cross-shore wind conditions.