Further Severe Thunderstorm Electrification and Precipitation Study (STEPS): Continuing Investigations of Sprites and Their Parent Storms and Lightning Discharges

Fma Research, Inc., Fort Collins CO

Investigators

Abstract

Transient luminous events (TLEs) such as red sprites, blue jets, and elves are spectacular phenomena that link tropospheric electrical activity with the stratosphere and mesosphere. These phenomena are almost always associated with positive cloud-to-ground lightning, which occurs less frequently than negatively charged lightning. Two storm types are known to produce positive lightning, namely supercell storms and nocturnal mesoscale convective systems. The STEPS project (Severe Thunderstorm Electrification and Precipitation Study), conducted in western Kansas in the early summer of 2000, provided the most comprehensive data available on sprites and sprite-producing storms. More than 1200 TLEs were observed and video-recorded at the Yucca Ridge Field Station of FMA Research, Inc. These data were collected in association with other storm observations on STEPS, including dual-Doppler and polarimetric radar data, aircraft microphysical measurements, high-resolution lightning maps, and balloon-borne measurements of the electrical field. This award supports further analysis of the TLE observations from STEPS, and enables the continuation of sprite monitoring during the summers of 2003-2005. The main objectives are (1) to characterize the relationship between lightning and sprites; (2) to classify the storm types that do and do not produce sprites. The approach is to analyze the TLE records from STEPS in relation to the radar, lightning, and other data. Results will be an improved understanding of the conditions attendant to sprite formation, and hence the physics of TLEs.