Mechanisms of Aerosol-Induced Invigoration in Deep Convective Storms

Many studies have demonstrated that increased aerosol loading in deep convective storms leads to higher storm updraft speeds. This invigoration of storms by aerosol particles was originally attributed to additional freezing of liquid water due to the suppression of rain formation in more polluted conditions. More recently, hypotheses have been put forward suggesting that increased condensation in the warm phase of storms is the primary driver of the invigoration. In this study we try to unravel this microphysical complexity by running a series of cloud-resolving model simulations in which the physical processes underlying these invigoration mechanisms are systematically turned on and off. The results support the idea that the warm phase of storms can drive the aerosol-induced invigoration. Both the lower and upper portions of the cloud droplet region contribute to this invigoration. The ice phase of the storm appears to play only a secondary role.