Weakening of typhoon-induced subsurface cooling in the western North Pacific during the last two decades

Understanding the subsurface oceanic thermal response to typhoons has become increasingly complex owing to changes in the oceanic environment and typhoon characteristics in recent decades. To address this issue, this study compared subsurface thermal changes in the western North Pacific between 2003–2012 and 2013–2022 by compositing typhoon with oceanic profile data. Results indicated that the average cooling in the upper layer (0–50 m) following typhoon passage intensified from −1.12°C to −1.22°C, an increase of 8.9%, primarily driven by increased typhoon wind speeds and decreased mixed-layer depth. By contrast, the average cooling in the subsurface layer (130–170 m) weakened from −0.80°C to −0.56°C, representing a 30% reduction. This weakening was more closely related to changes in oceanic preconditioning, particularly the decrease in cooling inhibition index and the shoaling of the mixed layer, while the decadal change in typhoon translation speed was not statistically significant. Furthermore, the cooling recovery rate in the upper layer (0–50 m) after typhoon passage became slower, likely due to enhanced ocean stratification. These findings offer new insights into typhoon-induced oceanic cooling under evolving climate conditions and highlight the importance of subsurface processes in modulating ocean–atmosphere interactions.