Spatiotemporal Variability of Tropical Cyclone Induced Ocean Heat Uptake and Its Effect on Ocean Heat Content

Tropical cyclone (TC) can pump heat downward through inducing intense vertical mixing. Many efforts have been made to estimate the magnitude of TC-induced ocean heat uptake (OHU), but the spatiotemporal variability of TC-induced OHU remains unclear. This study uses satellite-observed sea surface temperature (SST), subsurface temperature profiles, and turbulent heat fluxes to investigate the spatiotemporal variability of TC-induced OHU and its potential impacts on ocean heat content (OHC) during the period 1985-2018. It is found that category 3-5 TCs dominate the TC-induced OHU, accounting for ~70% of overall amount of TC-induced OHU globally each year. The time series of TC-induced OHU in global and regional oceans exhibit evident interannual-to-interdecadal variability, which is closely related to the TC power dissipation index (PDI). We further decompose PDI into TC intensity, frequency, and duration and find that category 3-5 TC frequency, annually averaged TC intensities, and durations all contribute to the variability of TC-induced OHU except that the averaged TC intensities have no significant relations with the TC-induced OHU in the North Indian Ocean, South Indian Ocean, and Southwest Pacific. In addition, the TC-induced OHU is shown to be responsive to equatorial SSTs rather than tropical SSTs, implying that the TC-induced OHU is modulated by El Niño-Southern Oscillation (ENSO). The TC-induced OHU might have the potential to influence OHC variability, particularly in the equatorial Pacific, where there is significant TC-induced OHU convergence. It has an important implication that TC-induced OHU might have potential effects on ENSO evolution.