Determination of concentration of charged particles in various regions of thunderstorms

Abstract:

During the Severe Thunderstorm Precipitation and Electrification Study in 2000, data on hydrometeor sizes and charges were obtained in thunderstorms using an optical array probe modified by the New Mexico Institute of Mining and Technology and mounted on the South Dakota School of Mines and Technology armored T-28 research aircraft. Analysis yielded quantitative observations of hydrometeor size and charge data in selected regions of storms with relatively low concentrations of charged particles. In most regions hydrometeor concentrations were so high that there were multiple charged particles in the probe sample volume at the same time and quantitative charge analysis was not possible. While it is impossible to reliably determine individual particle charges in these high concentration regions, we can use Poisson statistics to estimate the total number concentration of charged particles based on the fraction of records with just one particle in them. We compare these number concentrations for different thunderstorm regions, including updrafts, flanking cells, core precipitation regions, and trailing stratiform regions, at approximately the -10 C level, in several thunderstorms. We will discuss the implications of these results for understanding charge-separation processes in thunderstorms.