Evaluating the impacts of cloud processing on resuspended aerosol particles after cloud evaporation using a particle-resolved model

In this work, we quantified the changes in aerosol mixing state using a particle-resolved model. To this end, we coupled the particle-resolved aerosol model PartMC-MOSAIC with the aqueous chemistry module CAPRAM 2.4 and designed cloud parcel simulations that mimicked several cloud cycles that a particle population may be exposed to in polluted urban environments.

With ammonium nitrate and ammonium sulfate added to the activated particles, after the cloud evaporated, the activation potential of the resuspended aerosol particles increased for supersaturation thresholds lower than the maximum supersaturation attained in the cloud. Formation of sulfate and nitrate increased the internally mixed state of all particle populations, quantified by the mixing state index chi. The change of aerosol mixing state due to aqueous-phase chemistry was related to the fraction of activated particles.