Effects of Black Carbon Aerosols on Tropical Cyclones

The GFDL 50-km HiRAM model is used to study the effect of aerosol radiative and microphysical perturbations on the frequency of tropical cyclones. The atmospheric-only effects of aerosols on tropical cyclones are of comparable magnitudes to those of greenhouse gases. The calculated global reduction in frequency is consistent with thermodynamic arguments. However, a zonally asymmetric response in the convective mass flux can be seen across the tropics. In the meridional direction, the interhemispheric asymmetry of black carbon manifests in a weakening of the DJF Hadley cell, but not a strengthening in the JJA Hadley cell, possibly a result of the global convective mass flux constraint. These issues are further explored through Wheeler-Kiladis wave analysis as well as idealized uniform perturbations of black carbon aerosols.