Gaps in the evidence for aerosol invigoration of storms exposed
Fast, Jerome D — Pacific Northwest National Laboratory
Area of research
Based on critical review of key theoretical, modeling, and observational studies, this paper concludes that net invigoration of deep convective updrafts via condensational or mixed-phase pathways is at best highly questionable. Based on this finding, steps are provided that support a path forward for scientific progress in this area.
The review’s first recommendation for the research community is to determine a common definition for aerosol invigoration of storms. Many studies conflate changes in the updraft speed that defines a storm’s convective intensity with changes in observable properties, such as precipitation, lightning, and radar reflectivity, that do not necessarily require a change in updraft speed. Secondly, estimates of aerosol effect magnitudes across various atmospheric and cloud conditions are needed to design observational and modeling approaches that have a reasonable chance at isolating them. Lastly, much more research is required to constrain a plethora of uncertain cloud processes and their multiscale interactions with the ambient environment to isolate and quantify aerosol effects.
Hypothesized aerosol invigoration of deep convection has received significant attention in the research community because of its modulation by anthropogenic emissions that affect aerosol properties. Foundational theoretical, modeling, and observational invigoration studies have methodological shortcomings that render their conclusions and interpretations by many subsequent studies highly questionable. Methodological recommendations are made to limit these shortcomings in future studies in addition to suggestions for observational targets and research that could advance knowledge of aerosol–deep convection interactions.