Environmental & Climate Sciences Department Seminar

We have performed some new theoretical calculations based on parcel theory to quantify possible invigoration by aerosols in deep convection due to warm phase and cold phase processes. In the warm phase we find that reduced supersaturation causes enhanced buoyancy, but that enhancement diminishes as the parcel ascends to higher levels. In the cold-phase, which is traditionally where invigoration is thought to occur, we find instead that under most scenarios polluted parcels are actually weaker than clean parcels. Furthermore, the magnitude of change due to the cold-phase processes is generally small. These results differ from previous work due to our assumption of gradual freezing and gradual unloading rather than instantaneous freezing and unloading. Overall, we find that the warm phase and cold phase processes typically counteract one another and act to minimize the total invigoration of updrafts in polluted storms.