Journal Article

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

Zhang, Han, Zhang, Haoyu, Liu, Yu, Chen, Dake, Yu, Kai

2025

Overview

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. Plain Language Summary Tropical cyclones (TCs) often induce sea surface temperature (SST) cooling through intense mixing processes. However, the long‐term changes in extreme TC‐induced cooling (TCC) over the past four decades in the Northwest Pacific (NWP) remain relatively understudied. Utilizing multi‐source data sets and robust algorithms, we find that extreme TCC has significantly intensified over the past 40 years. In the last two decades, the TCC distribution has shifted more toward the extreme distribution observed in the previous 20 years. Moreover, basin‐scale trends vary considerably across different latitudinal regions, with a stronger trend observed in the subtropics. By applying the Cooling Inhibition Index (CI) and an improved Potential Intensity (PI) framework, we demonstrate that the CI effectively explains variations in extreme TCC. Furthermore, compared to PI calculations based on SST alone, incorporating subsurface ocean temperatures into PI provides a more accurate representation of the long‐term changes in extreme TCC. Key Points Basin‐scale tropical cyclone‐induced cooling (TCC) exhibits opposite trends across different latitudinal basins Extreme TCC has been intensifying, particularly over the last two decades Long‐term variations in extreme TCC can be well explained by using the Cooling Inhibition index (CI)

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: air‐sea interaction / cold wakes / Cooling / cooling inhibition index / Cyclones / Hurricanes / Oceans / potential intensity / relative importance / Sea surface cooling / Sea surface temperature / Stratification / Surface cooling / Tropical cyclone intensities / Tropical cyclones / Upper ocean