The responses of cyclonic and anticyclonic eddies to typhoon forcing: The vertical temperature-salinity structure changes associated with the horizontal convergence/divergence

The responses of the cyclonic eddies (CEs) and anticyclonic eddies (AEs) to typhoon forcing in the Western North Pacific Ocean (WNPO) are analyzed using Argo profiles. Both CEs and AEs have the primary cooling at the surface (0-10 m depth) and deep upwelling from the top of thermocline (200 m depth) down to deeper ocean shortly after typhoon forcing. Due to the deep upwelling, part of warm and fresh water at the top of AEs move out of the eddy, which leads to a colder and saltier subsurface in the AEs after the passage of the typhoon. In contrast, the inflow of warm and fresh water heats and freshens the subsurface in the CEs to compensate the cooling induced by the typhoon. This explains why the observed strong SST cooling were much less than modeled, since the AEs are more frequent than CEs in the WNPO. It indicates that there is divergence (convergence) of warm and fresh water in the surface of AEs (subsurface of CEs). The divergence-convergence effects of the AEs and CEs lead to the secondary cooling center locate at a shallow layer of 100 m in the AEs and a much deeper layer of 350 m in the CEs. This shallow divergence-convergence flow could lead a shallow overturning flow in upper oceans, which may potentially influences the large-scale ocean circulations and climates. Plain Language Summary The warm and fresh water diverges from anti-cyclonic eddies (AEs) but converges into the cyclonic eddies (CEs), in response to typhoon forcing. This explains why the observed strong SST cooling were much less than modeled, since the AEs are more frequent than CEs in the Western North Pacific Ocean. And it also shift the secondary cooling center to a shallow layer of 100 m in the AEs and to a much deeper layer of 350 m in the CEs. This shallow divergence-convergence flow could lead a shallow overturning flow in upper oceans, which may potentially influences the large-scale ocean circulations, biomass concentration and climates.