Large-Scale Tropical Circulation Intensification by Aerosol Effects on Clouds

This study addresses a critical gap in understanding anthropogenic influences on tropical climate dynamics by investigating the impact of aerosol-cloud interactions on large-scale circulation. Despite extensive research on greenhouse gas-induced warming and its effects on tropical circulation, the impact of aerosols, particularly their interactions with clouds, on large-scale circulation remains understudied. Utilizing large-domain radiative convective equilibrium cloud-resolving simulations, this research demonstrates that increasing aerosol concentration intensifies tropical overturning circulation, evaluated at the mid-troposphere (Formula presented.), strongly correlating with domain mean cloud and radiative properties. Employing a weak temperature gradient approximation, I attribute variations in (Formula presented.) to changes in clear-sky radiative cooling rather than stability. These radiative cooling changes are linked to humidity changes driven by warm rain suppression by aerosols. This study's findings underscore the need to take into account microphysical changes, particularly aerosol concentrations, when studying anthropogenic effects on tropical circulation.