Environmental & Climate Sciences Department Seminar

Cold pools, cool gusty outflows at the surface that are formed by latent cooling associated with convective storms, have long been recognized as important atmospheric features. They influence the development and organization of convective storms; they impact surface fluxes of energy, moisture, and momentum; they loft and transport dust and other particulates; and they have been linked to a phenomenon called "Thunderstorm Asthma," whereby pollen grains can osmotically rupture into sub-pollen particles that easily penetrate the lungs. This latter phenomenon has been the subject of recent research and formed the base motivation for an NSF-sponsored project called BioAerosols and Convective Storms (BACS). The overall goal of BACS is to characterize the fluxes of biological particles between the surface and atmosphere, assess the vertical distribution of bioaerosols and how this distribution is influenced by convective cold pools, and investigate feedbacks between cold pools, bioaerosols, and convective storms. In this talk, I will present an overview of the first field phase of BACS (BACS-I), which took place in May-June 2022 in the plains of northern Colorado. I will highlight some of the measurement systems employed, including drone-based methodologies for measuring the vertical structure of cold pool thermodynamics and aerosol concentrations. I will then show some preliminary results from BACS-I. These include variability in the observed properties and vertical structure of cold pools, which is particularly strongly modulated by the class of parent convection producing the cold pool; variation in the observed responses of bioaerosols to cold pool passages, even on the same day; and modeling work on the impact of successive cold pools (two or more cold pools passing over the same area on the same day) on aerosol transport and vertical redistribution. Finally, I will highlight implications for cold pool impacts on bioaerosols and avenues for future work, including bioaerosol feedbacks to convection.