Electrification and Lightning of Severe Storms and Mesoscale Convective Systems in STEPS and on the Southern Great Plains

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

This project is devoted to the study of relationships among the wind field, the electrical structure, the microphysics, and the lightning produced by both isolated thunderstorms and large systems of convective storms. It is based on the continuing analysis of data collected during the STEPS project of 2000 and includes collection of additional data in Oklahoma during the summers of 2003 and 2004. The data consist chiefly of balloon soundings of the electric field, polarimetric radar observations, and data from a lightning mapping array (LMA). Specific questions to be answered are: (1) Are lightning flash rates proportional to the mass of graupel in a storm? (2) Does the inverted electrical polarity of some storms have a microphusical cause? (3) Do the long horizontal flashes observed in mesoscale convective systems originate in the region of deep convection or in areas of lighter precipitation? (4) More generally, what are the characteristics of lightning flashes in mesoscale convective systems, and how are they affected by cloud microphysical structure? Answers to the question require synthesis of data from the different observing systems and analyzing the data in the light of different theories of charge production, separation, and lightning initiation. Results will contribute not only to the understanding of the physics of lightning, but will also be useful in developing techniques for assimilating lightning in numerical forecasting models and in learning how to use lightning data to warn of storm hazards. The work is done in collaboration with other participants in STEPS, in particular New Mexico Institute of Mining and Technology in the analysis of LMA data and Colorado State University in the analysis of polarimetric radar data.