The Impact of Aerosol Size on the Efficacy of Marine Cloud Brightening

The injection of sea salt produces a wide range of cloud microphysical and radiative responses in simulations of subtropical Marine Cloud Brightening (MCB) in the global climate models CESM2, E3SMv2, and CanAM5.1-PAM. Comparisons with an adiabatic cloud parcel model show that differences in the simulated cloud droplet number can be attributed to differences in parameterizations of aerosol activation, sea salt particle size, aerosol lifetimes, and cloud updraft velocities. These findings establish a roadmap for the analysis of MCB simulations within Earth System Models and the identification of model improvements that are urgently needed for more robust assessments of MCB cloud and climate impacts.