This project will advance understanding of storm electrification through a combination of instruments and techniques, including time-of-arrival and broadband interferometric mapping of lightning discharges inside storms, wideband electric and magnetic field measurements, high-speed video recordings of flashes, energetic radiation measurements inside storms, and dual-polarization meteorological radar storm observations. A particular initial focus will center on data collected during the May-June 2012 Deep Convective Clouds and Chemistry (DC3) study to be conducted in May-June 2012, for which this team will provide high-quality lightning mapping observations in the CSU-CHILL/North Colorado study area. The intellectual merit of the research will result primarily from the scientific investigations. Specific issues to be addressed include investigating the mechanism by which lightning is initiated, determining the nature of positive- and negative-polarity breakdown, homing in on the details of various discharge processes, and further differentiation of various types of lightning (such as blue- and gigantic-jets, bolts-from-the-blue, energetic compact intracloud discharges, and triggered lightning. In addition to individual lightning flashes, four-dimensionally mapped observations of the overall lightning activity will be used to infer storms' electrical structures, which will in-turn be compared with dual-polarization radar observations of associated microphysical and dynamical structures. The latter studies are to be carried out in conjunction with the Colorado State University (viz. CSU-CHILL) radar beginning with the DC3 investigations, where a more permanent, Lightning Mapping Array (LMA) will be set up and operated. These studies will help assess and quantify the effects of storm electrification and lightning on important trace atmospheric chemical constituents. Of particular subsequent interest will be studies of supercell and hail-producing storms, storms exhibiting inverted polarity signatures, positive cloud-to-ground lightning discharges, and wintertime lightning, and will also benefit from additional data collected by the S-POL radar operated by the National Center for Atmospheric Research.
Collectively, broader impacts of these studies will include improved use and interpretation of lightning data in a) short-term forecasts of thunderstorm severity and intensification, b) determining the effect of lightning and electrified storms on atmospheric chemistry, c) detecting and monitoring volcanic eruptions, and d) validating space-borne lightning observations in advance of launches of the GOES-R and European geosynchronous satellites. The North Colorado LMA will also provide detailed observations of lightning occurrences and effects on the major energy-producing windfarms along the Colorado/Wyoming border. Work will also continue on studying underground transients produced by lightning, of substantial interest to the coal-mining and electric power industries. This work sill serve to further continued development of lightning mapping technology and dissemination of this technology to other research groups and operational users, as well as through graduate education and training of the next generation of researchers.
