Aerosol Association with Severe Weather in the Great Plains

Aerosols particles may serve as cloud condensation nuclei (CCN) and therefore play an important role in modulating cloud microphysics, to the point where convective storm intensity may be altered. The purpose of this study is to determine the impacts of biomass burning aerosols on convective storms over the Great Plains, especially the southern Great Plains, and to show synoptic regimes characterizing differing aerosol concentrations. A new technique to identify days with a high concentration of biomass burning aerosols was developed by using organic carbon, potassium, zinc, and bromine as the predominant tracers. An eleven-year climatology (2002-2012) for the biomass burning tracers was produced to identify days on which biomass burning particles were present, and an average concentration of these tracers was obtained from two different sensors in western Oklahoma: Ellis and Wichita Mountains. Once prevalence of biomass burning particles was identified for each day, days were classified into high (upper 30%), medium (middle 40%), and low (lowest 30%) biomass burning particle concentration. Only March through June was considered since this is climatologically the convective season in the Southern Great Plains. Days with severe thunderstorms and with similar thermodynamic (CAPE) and kinematic (shear) environments were chosen as case study days, from which storm report data were obtained and compared. Additionally, composite synoptic regime and a set of trajectories were obtained for each aerosol concentration category. Lastly, differential reflectivity and correlation coefficient values were examined to compare the microphysics of thunderstorms occurring on days of different aerosol concentration. Case studies of High Plains and Oklahoma storms were examined. This study is one of the first observational studies to examine aerosol effects on convective storms in the Great Plains region. Adviser: Matthew S. Van Den Broek