Oceanic Control on the Long-Term Intensification of Extreme Tropical Cyclone-Induced Sea Surface Cooling

Abstract

Tropical cyclone (TC)-induced sea surface temperature cooling (TCC) has both local and basin-scale effects, but the roles of upper ocean conditions and TC intensity in its long-term variability remain unclear in the Northwest Pacific (NWP). This study finds that annual cumulative basin-scale TCC has increased (21.51 ± 6.41°C/yr), driven primarily by enhanced TCC in the western coastal and mid-latitude regions north of 20°N (39.26 ± 6.67°C/yr), while a decreasing trend is observed south of 20°N (−17.75 ± 4.42°C/yr). At the local scale, TCC has intensified (0.08 ± 0.01°C/decade), with extreme events (top 95%) increasing even more (0.09 ± 0.01°C/decade). The probability of typical TCC (>1°C) has almost doubled over the last four decades, and the TCC distribution has shifted rightward, reflecting stronger TCC. These trends are primarily driven by changes in ocean stratification, with variations in TC intensity playing a secondary role.