The Effect of Wind-Wave-Current Interaction on Air-Sea Momentum Fluxes and Ocean Response in Tropical Cyclones

In this paper, the wind-wave-current interaction mechanisms in tropical cyclones and their effect on the surface wave and ocean responses are investigated through a set of numerical experiments. The key element of the authors' modeling approach is the air-sea interface model, which consists of a wave boundary layer model and an air-sea momentum flux budget model. The results show that the time and spatial variations in the surface wave field, as well as the wave-current interaction, significantly reduce momentum flux into the currents in the right rear quadrant of the hurricane. The reduction of the momentum flux into the ocean consequently reduces the magnitude of the subsurface current and sea surface temperature cooling to the right of the hurricane track and the rate of upwelling/downwelling in the thermocline. During wind-wave-current interaction, the momentum flux into the ocean is mainly affected by reducing the wind speed relative to currents, whereas the wave field is mostly affected by refraction due to the spatially varying currents. In the area where the current is strongly and roughly aligned with wave propagation direction, the wave spectrum of longer waves is reduced, the peak frequency is shifted to a higher frequency, and the angular distribution of the wave energy is widened.