Dynamic Modulation of Storm Size on Upper-Ocean Temperature Response to Tropical Cyclones

Abstract Satellite observations reveal storm size as a leading driver among typical tropical cyclone (TC) attributes in modulating TC-induced sea surface temperature (SST) cooling. However, the dynamic mechanisms via which storm size modulates SST cooling and upper-ocean temperature response remain less understood. Here, we employ three-dimensional Price–Weller–Pinkel (3DPWP) model to explore the dependence of ocean dynamic processes controlling temperature response on changing storm sizes [represented by 34-kt wind radius (R34); 1 kt ≈ 0.51 m s −1 ]. Consistent with satellite observations, model simulations show that larger TCs generate stronger SST cooling magnitude and broader spatial extent. As storm size changes, vertical mixing consistently remains the dominant process, accounting for 69% on average of the total cooling. With increasing R34 from 100 to 400 km, its contribution inside R34 region increases modestly from 67% to 71%. The cooling contribution from upwelling is concentrated near the TC center and increases with storm size, rising from 18% in R34_100 to over 30% in R34_400. The impact of surface heat flux on SST cooling is greater outside R34 region, and its contribution decreases with storm size from 56% to 19%. Particularly, horizontal advection, though not a primary driver, becomes increasingly important in enhancing the cold wake asymmetry as storm size increases. Compared with translation speed and radius of maximum wind speed, R34 exerts a more profound effect on SST cooling, particularly on its spatial extent. These findings underscore the significant impact of storm size in TC–ocean interactions, with implications for improving TC intensity forecasts and risk assessments. Significance Statement Storm size plays a critical role in modulating tropical cyclone (TC)-induced sea surface temperature (SST) cooling, but the underlying mechanism remains less understood. Through numerical experiments, this study reveals that larger TCs produce stronger and more extensive SST cooling, primarily via enhanced vertical mixing. While upwelling becomes more influential near the TC center with increasing storm size, contribution of surface heat flux decreases, especially outside the R34 region. Horizontal advection redistributes the temperature anomalies and significantly increases the cold wake asymmetry. Furthermore, R34 has a greater impact on SST cooling than translation speed and radius of maximum winds (RMW), particularly on its spatial extent. These findings improve our understanding of TC–ocean interactions, offering insights into better TC intensity forecasts and hazard assessments and aiding disaster preparedness and risk management.