Polarimetric Radar Observations of Aerosol Effects on the Microphysical Structure of Great Plains Thunderstorms

Aerosols serving as cloud condensation nuclei (CCN) are crucial to the microphysical structure of thunderstorms. They can also alter the rate of cloud microphysical processes, the moisture profile and the local temperature via latent heating in the early stage of thunderstorm development. The purpose of this study is to determine the influence of CCN concentration on the microphysics of continental thunderstorms in northwest Oklahoma. Approximately 66 storms were observed by the Weather Surveillance Radar-1988 Doppler (WSR-88D) at Vance Air Force Base, Oklahoma (KVNX). Rapid Refresh (RAP) model output are used to describe the near storm convective environment. The correlation between CCN concentration and mean low-level differential reflectivity (Z_DR) is found to be negative shortly after convection initiation. While the most unstable convective potential available energy (MUCAPE) has moderate positive correlation with the low-level Z_DR distribution, other environmental parameters are less correlated. The ZDR column vertical extent was also found to show positive correlation to CCN concentration during the thunderstorm’s mature stage. These effects of CCN concentration on thunderstorm characteristics are in general agreement with the results of other studies. Hypotheses are presented to describe how CCN may alter storm microphysics and require differing interpretation of polarimetric signatures.