Modulation of Tropical Convection-circulation Interaction by Aerosol
Indirect Effects in a Global Convection-permitting Model
Abstract
Observations suggest tropical convection intensifies when aerosol
concentrations enhance, but quantitative estimations of this effect
remain highly uncertain. Leading theories for explaining the
intensification are based on the dynamical response of convection to
changes in cloud microphysics independently from possible changes in the
environment. Here, we provide a new perspective on aerosol indirect
effects on tropical convection by using a global convection-permitting
model that realistically simulates convection-circulation interaction.
Simulations of radiative-convective equilibrium show that pollution
facilitates the development of deep convection in a drier environment,
but cloud condensates are more likely to be exported from moist clusters
to dry areas, impeding the large-scale moisture-convection feedback and
limiting the intensity of maximum precipitation (30 vs. 47 mm
h\textsuperscript{-1}). Our results emphasize the
importance of allowing atmospheric phenomena to evolve continuously
across spatial and temporal scales in simulations when investigating the
response of tropical convection to changes in cloud microphysics.