UC Davis

Abstract Previous modeling studies have shown a connection between higher aerosol concentrations and heightened updraft speeds in convective clouds, an effect known as aerosol‐induced invigoration. Observational evidence of this phenomenon, however, is inconclusive. We seek to provide a statistically robust, observational assessment of the effects of aerosol invigoration on isolated, developing, midlatitude, deep convective updraft speeds. This study uses geostationary satellite data to track approximately 225 storms over the Southern Great Plains. We show using cloud resolving model simulations that convective updraft speeds are proportional to the cloud top rise rate. After controlling for meteorology, the results suggest that high concentrations of small aerosol particles can invigorate convection, whereas accumulation mode particles may enervate updrafts at mid to upper levels of the storms. The statistical significance of an invigoration effect increases under environmental conditions that promote high supersaturation (strong updrafts, extensive warm phase regions), while the significance of an enervation response is enhanced under conditions that promote entrainment (high wind shear, lower cloud bases). These results are largely in agreement with many past modeling studies but have not been seen previously in observations. Our findings suggest that future efforts in the field should reject the framework of invigoration or enervation and instead focus on the specific conditions under which each response is expected. Plain Language Summary While modeling studies have previously linked greater amounts of aerosol particles to changes in storm updraft speeds, the difficulty in detecting such a relationship using observations has largely hindered the ability to validate this phenomenon. To bridge this gap, this study uses satellite data, ground‐based aerosol measurements, and robust statistical methods to detect aerosol influences on thunderstorm cloud tops over Oklahoma. Ultimately, we cannot prove that aerosols have altered the rise of cloud tops. We do, however, uncover specific conditions that can improve the ability to detect an aerosol effect. We find that high concentrations of aerosols could strengthen the rise of the cloud top under high supersaturations but weaken its ascent with greater dilution of the surrounding air. These findings are largely consistent with the existing literature. Thus, we emphasize that polluted storms are equally likely to see a faster or slower rise in their cloud tops and that their specific conditions will dictate which response can be expected. Key Points The likelihood of observing an invigoration effect increases in environments which promote high supersaturations The likelihood of detecting an enervation effect strengthens in environments which promote entrainment The observational results of this study are largely qualitatively consistent with previous modeling studies