Effect of Aerosol Properties on Aerosol-Cloud Interaction and Regime Dependence

Abstract:

A central problem in cloud physics in general and in studying aerosol-cloud interactions in particular is to accurately simulate and understand cloud droplet size distributions as a function of aerosol and cloud dynamical properties. Our previous study (Chen et al., 2016) shows that aerosol-cloud interactions in terms of both number effect (effect through the change in cloud droplet number concentration) and dispersion effect (effect through the change in the spectral shape of cloud droplet size distributions) exhibit strong regime dependence, and three distinct regimes (aerosol-limited regime, updraft-limited regime and transitional regime) can be identified based on their joint dependence on aerosol number concentration and updraft velocity. This work is an extension of this previous study to examine the influences of other important aerosol properties in addition to aerosol number concentration, including aerosol mean radius, width of the aerosol size distribution, and chemical composition as represented by the Kappa parameter. Their influences on number effect, dispersion effect and their regime dependence will be reported. A new MPI-accelerated (Message Passing Interface accelerated) version of the cloud parcel model is used that allows for 356 times acceleration with strong linear scalability up to 576 CPU cores. Physical understanding of aerosol properties on aerosol-cloud interaction and regime dependence is provided; efforts will be made to apply the new understanding to improving the parameterization of aerosol-cloud interactions.