Tropical Cyclones Can Promote Subsurface Marine Heatwaves and Extend Their Persistence

Marine Heatwaves (MHWs) are extreme oceanic warming events with profound ecological consequences. Conventional wisdom posits that tropical cyclones (TCs) act as "terminators" of MHWs through strong surface cooling; however, the complex three-dimensional spatiotemporal evolution of MHWs during such interactions is often overlooked. Using a high-resolution ocean model and four-dimensional tracking techniques, we propose a novel conceptual framework for TC-driven MHW evolution, termed the "sink–latent–reemergence" mechanism. We analyzed the record-breaking MHW in the Bohai Sea and Yellow Sea, where three consecutive TCs simultaneously dampened MHWs in the mixed layer while intensifying them in the subsurface layers. Numerical experiments reveal that this transformation is driven by enhanced surface latent heat release, anomalous vertical mixing, and advection. Consequently, MHW thermal anomalies can be sequestered below the mixed layer, isolated from direct air–sea heat exchange, which substantially prolongs their duration and enables their potential reemergence in the following winter. Analysis of four additional historical events further confirms that TCs do not strictly extinguish MHWs but can transform their vertical structure. These results provide new insights intoTC–MHW interactions, with critical implications for understanding and predicting the persistence of extreme warming events in marginal seas.