Numerical Studies of Electrification and Lightning in Severe Thunderstorm Electrification and Precipitation Study (STEPS) Storms

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

An advanced numerical cloud model will be used to simulate the types of storms observed in the Severe Thunderstorm Electrification and Precipitation Study (STEPS) of the summer of 2000. The three-dimensional dynamic simulation model includes detailed microphysical, electrical, and lightning parameterizations and produces realistic storms and lightning in simulations of several types of thunderstorms. Observations during STEPS were among the most complete ever taken for electrification studies. They included polarimetric radar measurements, dual-Doppler measurements, three- dimensional lightning flash patterns obtained by the Lightning Mapping Array, in-situ cloud and electrical measurements obtained by instrumented balloons and a storm-penetrating aircraft, and surface observations from a mobile mesoscale network. The data will be compared with simulations to improve the understanding of interactions among kinematics, precipitation production, and electrification in severe storms. Examples of the topics to be investigated are (1) the influence of vertical air motions and precipitation on the production of lightning; (2) the influence of storm type (e.g., unicell, multicell, supercell) on flash rates and other lightning characteristics; (3) conditions attendant to the production of unusual lightning activity, such as exceptionally high flash rates or positive cloud-to-ground lightning. It is expected that the research will lead to ways of using lightning data to help diagnose and forecast severe weather.