Pathways of tropical cyclone induced subsurface warming in the Northwestern Pacific Ocean

Tropical cyclones (TCs) trigger vigorous upper ocean mixing, pumping surface warm water into the ocean subsurface. TC-induced ocean subsurface warming (OSWTC) may be transported meridionally and influence ocean heat distribution, particularly in the Northwestern Pacific where TCs are most active. Based on ocean reanalysis products, a Lagrangian Particle Tracking analysis is conducted by releasing virtual particles representing OSWTC in the Northwestern Pacific to investigate the major pathways of OSWTC in the ocean. It is found that more than 50% of total particles are primarily moved westward and then join the Kuroshio Current, flowing northeastward towards the Kuroshio Extension after one year of release. Meanwhile, other particles moved eastward along the Subtropical Countercurrent (~ 4%), westward across the Luzon Strait into the South China Sea (~ 8%), and southward along Mindanao Current (~ 4%). In addition, about a quarter of the OSWTC particles remain locally beneath the mixed layer after one year of release. These results indicate that the majority of OSWTC can contribute to the meridional heat transport in the Northwestern Pacific. Both background currents and westward propagation constrained by differential rotation (Beta effect) contribute to the movements. We also find that the meridional movements of OSWTC are sensitive to the formation latitudes. A more northward formation location of OSWTC corresponds to a more northward heat transport. Since the TC tracks move poleward with global warming, our results imply more northward TC-induced ocean heat transport in the future.