Local forcing of summer marine heatwaves in China's northern and eastern seas: Shortwave radiation and wind stress

During the summer (June–August), marine heatwaves (MHWs) frequently occur in China's northern and eastern seas, including the Bohai Sea, Yellow Sea, and northern East China Sea. As a prominent marine environmental concern, these events have garnered widespread societal attention. However, the predictive capacity for such events remains constrained, underscoring the urgent need to comprehensively unravel the physical mechanisms governing their occurrence. In this study, we employ the Regional Ocean Modeling System to explore the local forcing factors driving MHW genesis. Our results reveal that the formation of summer MHWs is jointly determined by surface net heat fluxes, oceanic advection, and vertical mixing, with their relative contributions varying significantly across geographical locations. The formation of summer MHWs is closely related to surface wind stress anomalies. Under the background of weakened wind forcing, the temperature rise during the heat accumulation phase of MHWs is primarily driven by increased solar radiation, reduced cloud cover, and shoaling of the mixed layer. The suppression of vertical mixing further enhances heat accumulation in regions with water depth exceeding 50 m. These findings advance our understanding of the formation mechanisms of summer MHWs in China's northern and eastern seas, while improving the predictive capacity for such events.