Projected Tropical Cyclone Frequency Changes Under the Impacts of Different Anthropogenic Forcings

Anthropogenic climate change is associated with changes in the large-scale circulation of the tropical atmosphere, which modulates tropical cyclone (TC) genesis. To better understand the impacts of anthropogenic forcing on TC activity, we investigate the individual impacts of anthropogenic aerosols, greenhouse gases and biomass burning emissions using the CESM2 Single Forcing Large Ensemble (SFLE) Project. The frequency and location of TC genesis is estimated using a dynamic genesis potential index (DGPI). Increases in anthropogenic aerosol emissions led to a northward shift and a net increase in TC frequency over the Atlantic, while increases in greenhouse gas emissions resulted in a southward shift and a net decrease in TC frequency. DGPI does not show significant effect of biomass burning emissions on TC frequency. TC frequency is also estimated in the other basins, and the changes of different dynamic and thermodynamic environmental variables are examined to better understand the impacts of different forcing agents. The CESM2 SFLE simulations are also compared to the CESM1 SFLE simulations, and the similarities and differences will be briefly discussed.