Examining Relationships Between Environmental Conditions and Electrical Characteristics in Convective Storms

Lightning Mapping Arrays (LMAs) are now deployed in Alabama, Colorado, Oklahoma/West Texas, New Mexico and Washington, D.C. LMAs allow for high spatial and temporal resolution of very high frequency (VHF) lightning sources supporting a wide variety of storm electrification studies, especially when combined with radar data. The majority of thunderstorms in the United States are negative cloud-to-ground lightning (CG) dominant and have a main mid-level negative charge region, or so called “normal” polarity. A smaller fraction of storms are positive CG dominant, with mid-level positive charge (so called “inverted” storms). Lang et al. (2011) and other studies have shown that inverted storms are most frequent near the Kansas/Colorado border northeastward toward the upper Great Plains. This study expands the work done by Lang et al. (2011) to other regions of the country where storms form in different environments and are forced by different mechanisms. Comparisons of normal and inverted storms will illustrate the environmental and storm characteristics that produce mid-level positive charge and positive CG dominated storms. As shown in many studies such as Albrecht (1989) and Twomey (1977, 1990), aerosols also affect microphysical processes in clouds. Investigation of aerosol effects on storm electrification is also a component of this study. Analysis of the data will be carried out using the CLEAR statistical framework described in Lang et al. (2011). This fully modular and objective approach uses a series of programs to attribute environment data such as CAPE, shear and cloud base height along with lightning data to any storm. The CLEAR framework is also able to track a storm during its entire lifetime, allowing for studies of storm evolution and possible changes in lightning behavior. Studying the lightning characteristics of storms that form in different regions of the country and in different meteorological environments will give valuable insight to the cloud microphysical processes during storm formation and electrification.