Observational Evidence for Both Aerosol‐Induced Invigoration and Enervation

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.