Strengthening of the Kuroshio current by intensifying tropical cyclones.

A positive feedback mechanism between tropical cyclones (TCs) and climate warming can be seen by examining TC-induced energy and potential vorticity (PV) changes of oceanic geostrophic eddies. We found that substantial dissipation of eddies, with a strong bias toward dissipation of anticyclonic eddies, is directly linked to TC activity. East of Taiwan, where TCs show a remarkable intensifying trend in recent decades, the ocean exhibits a corresponding upward trend of positive PV anomalies. Carried westward by eddies, increasing numbers of positive PV anomalies impinge on the Kuroshio current, causing the mean current to accelerate downstream. This acts in opposition to decreasing basin-scale wind stress and has a potentially important warming impact on the extratropical ocean and climate.