Drivers of Multi-decadal Warming in the Main Development Region for Atlantic Hurricanes

More active Atlantic hurricane seasons occur during warm phases of the Atlantic Multi-decadal Oscillation (AMO), when the sea surface and upper ocean layer across the Main Development Region (MDR) are anomalously warm. Understanding the drivers of this warming can inform long-term planning for the major societal impacts of these intense storms. In this study, ocean and atmospheric reanalysis products are used to quantify the contribution of anomalous air-sea fluxes to ocean heat content (OHC) anomalies across the MDR. Over 1980-2018, air-sea heat flux anomalies explain 29% of the variance in OHC for the upper 100 m. The variability in air-sea fluxes is dominated by anomalies in the latent heat flux and shortwave radiation, in turn associated with anomalies in wind speed and cloud fraction respectively. Secondary influences on the OHC variability are attributed to anomalous ocean heat transport divergence, associated with changes in both the basin-scale circulation and Ekman dynamics, which are related to the same anomalous winds that modulate the turbulent surface fluxes. We thus see that coordinated physical mechanisms associated with the AMO may thus explain recent warming of the MDR that has been conducive to more intense hurricane seasons and more frequent landfall of destructive storms.