Strong impact of tropical cyclones on the genesis of subsurface marine heatwaves

Subsurface marine heatwaves are newly recognized extreme ocean events with profound impacts on global marine ecosystems. Previous studies have linked their formation to downwelling favorable surface winds, warm ocean eddies, and planetary waves, yet whether other potential drivers of these heatwaves exist remains unclear. The tropical cyclones are well known to induce a pronounced warming in the subsurface. Here, we show that the induced warming can efficiently trigger subsurface marine heatwaves. It is shown from an ocean reanalysis that such warming reaches the heatwave threshold at least once along the tropical cyclone life cycle for 79.4% of the tropical cyclones. Tropical cyclone-induced heatwaves thus account for up to 40.0% of the heatwaves in cyclone-active regions. The area and intensity of tropical cyclone-induced heatwaves have increased over the past two decades, likely due to the steady warming of subsurface temperatures. Tropical cyclones trigger up to 40% of subsurface marine heatwaves in cyclone-active regions, according to in situ observations and ocean reanalysis, which also suggests their area and intensity have increased over the past two decades due to long-term ocean warming.