Effect of small scale wind variations over the Kuroshio in the East China Sea

Abstract

Abstract The QuikSCAT satellite radar scatterometer has observed parallel bands of negative and positive wind stress curls on the inshore and offshore sides of the Kuroshio in the East China Sea, which were not seen in other low-resolution wind products. This study assesses the impact of these small-scale wind variations on ocean simulations by comparing two numerical experiments forced by monthly climatological wind with and without this small-scale component in an eddy-resolving ocean model. By affecting the Ekman upwelling and downwelling, the wind stress curls influence the temperature structure and ocean current. The results show that these small-scale wind variations can reduce the Kuroshio velocity on the onshore side and increase it on the offshore side, accompanied by a systematic cooling of the sea surface temperature (SST) along the Kuroshio path. Although these small-scale winds are prescribed in the East China Sea, they have a significant influence on the downstream surface kinetic energy south of Japan by affecting the state of the Kuroshio. These small-scale wind variations also modulate the seasonal variability of the Kuroshio. The results of this study help to understand various ocean simulations subjected to different wind stress products.