17AEROSOL Assessing the effect of cloud organization on cloud-aerosol interactions

Marine stratocumulus cloud responses to anthropogenic aerosol perturbations remain the largest source of uncertainty in estimating the anthropogenic forcing of the climate system. This uncertainty arises from complex feedbacks in cloud microphysics, thermodynamics, and dynamics. Recent studies have shown that the cell size of marine stratocumulus clouds plays a nontrivial role in regulating aerosol-induced cloud brightness. Large-scale organized clouds exhibit almost three times stronger response of cloud brightness to aerosol perturbation compared to small-scale clouds, primarily due to lower entrainment efficiency in the case of the former.

In this study, we enhance our understanding of how cloud organization influences cloud-aerosol interactions by applying a multiple linear regression approach to cloud properties in a large ensemble of large-eddy simulations of diurnal marine stratocumulus, with varying initial conditions of temperature, moisture, boundary layer height, and aerosol concentration. The impact of cloud organization conditions on clouds is further investigated by applying the same regression approach to the individual LWP budget terms driven by cloud top, base, lateral entrainment, and radiation. The critical meteorological conditions for cloud organization scale are also identified.