Dual Effects of Marine Heatwaves on Typhoon Intensity and Associated Heat Dissipation

Based on the positions of 1027 typhoons that passed through the Western Pacific (WP), East China Sea (ECS), and South China Sea (SCS), the results indicate that the category of marine heatwaves (MHWs) significantly decreases or dissipates after a typhoon’s passage, with stronger typhoons causing more pronounced dissipation. The presence of MHWs does not necessarily enhance typhoon intensity; in as many as 151 cases, typhoons weakened despite the presence of MHWs. Furthermore, case studies were conducted using three typhoons that traversed different regions—Hinnamnor (2022), Mawar (2023), and Koinu (2023)—to investigate the dual effects of MHWs on typhoon intensity and their dissipation using satellite observations and ocean reanalysis datasets. Results show that MHWs enhance typhoon intensity by increasing sea surface temperature (SST) and ocean heat content (OHC), while also strengthening stratification through a shallower mixed layer depth (MLD), creating favorable conditions for intensification. While MHWs may initially enhance typhoon intensity, the passage of a typhoon triggers intense vertical mixing and upwelling, which disrupts MHW structures and alters heat distribution, potentially leading to intensity fluctuations. The impact of MHWs on typhoon intensity varies in time and space, MHWs can sustain typhoon strength despite heat loss induced by the typhoon. Additionally, variations in OHC and the mean upper 100 m temperature (T100¯) were more pronounced in the inner-core region (R50) than in the outer-core region (R30), indicating that energy exchange is concentrated in the inner core, while broader air–sea interactions occur in the outer core. The results show that MHWs can enhance typhoon development by increasing stratification and SST but are also highly susceptible to rapid dissipation due to typhoon-induced impacts, forming a highly dynamic two-way interaction.