More Frequent and Intense Tropical Cyclone‐Heat Wave Compound Extremes Over the Coastal Regions of China in a Warmer Climate

Abstract In recent decades, the tropical cyclone (TC) and heat wave (HW) (TC‐HW) compound extreme event poses increasing threats to population over southeastern coast of China (SECC) under climate warming, yet their future projection remains uncertain. This study examines the projected changes in frequency, intensity, and spatial patterns of TC‐HW events over the SECC using observational data and high‐resolution climate model simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) High‐Resolution Model Intercomparison Project (HighResMIP). Based on the CMIP6 HighResMIP simulations, TC‐HW events are projected to be more frequent and much stronger in the future under the high‐emission scenario (SSP‐585). Specifically, tropical cyclones (TCs) induce prelandfall warming over the SECC land region, particularly over the eastern part, with magnitude exceeding 1.5°C relative to the summertime climatology for 1980–2010. Such prelandfall warming associated with TC is driven by subsidence and increased solar radiation, followed by postlandfall cooling with temperature anomalies reaching up to −1°C relative to the historical summertime climatology. In the future, the model projections indicate that TC‐HW events will be stronger, with temperature exceedance above 2°C, relative to the historical summertime climatology. Besides, TC‐HWs are also expected to be more frequent, with the annual occurrences projected to increase by 30–50 events compared with the historical period. Our analysis reveals that the projected increases in TC‐HWs are predominantly driven by the enhanced frequency and intensity of HWs under global warming. Moreover, TC‐HWs will exhibit broader spatial extent of influence as well as the prolonged durations even from TC genesis stages. These findings underscore the increasing risks of compound TC‐HW extremes in coastal China under the warming climate. Strengthening early warning systems and implementing urban heat mitigation strategies are critical to address these escalating threats.