Anomalously Electrified Storms in Colorado: A search for physical mechanisms

Previous research has shown that the electrical characteristics of storms in the High Plains region of the United States are often anomalously electrified. These storms are more likely to produce high flash rates and have positive charge regions at warmer temperatures compared to normal polarity storms. These differences are likely influenced by the unique environmental conditions conducive to the production of large liquid water contents at subfreezing temperatures. To understand how the environmental variables affect the microphysics and dynamics that produce anomalously electrified storms, detailed analysis of polarimetric radar and dual-Doppler derived winds will be carried out for a number of storms in various regions of the United States. Data from all regions of the Deep Clouds and Convective Chemistry (DC3) campaign during the summer of 2012 will be used along with X/S dual frequency radar data from the CHILL Microphysical Investigation of Electrification (CHILL-MIE) in northeast Colorado during the summer of 2013. Simultaneous dual-frequency observations provide additional microphysical information including higher resolution data along with differential attenuation and Mie scattering effects. These radar data will be used in concert with total lightning and charge structure information from Lightning Mapping Array (LMA) data to investigate lightning processes and evolution and their relation to microphysics and processes occurring in a storm.

Preliminary results include an investigation into “Zdr columns”, indicative of larger drops lofted above the freezing level, and their influence on first lightning and charge characteristics. Recent studies suggest that microphysical processes can be inferred from polarimetric variable changes along a parcel trajectory. This study explores the feasibility of this technique and the implications for production and maintenance of positive charge regions in thunderstorms.