Microphysical and Kinematic Storm Properties Affecting Electrification and Lightning Production

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)." Intellectual Merit: Under this award the Principal Investigator (PI) will continue investigating how microphysics and kinematics affect storm electrification and lightning production by using lightning mapping, electric field, radar, and other storm observations acquired in Oklahoma since 2003. The Oklahoma Lightning Mapping Array, the local National Weather Service 11-cm polarimetric radar, and a rapid-scanning 10 cm phased array radar have operated for several years. During the Thunderstorm Electrification and Lightning Experiment (TELEX) 2003 and 2004 and on other occasions since then, additional observations, including in situ storm soundings of the electric field, environmental soundings, and mobile 5-cm wavelength dual Doppler radar data, also were collected for select cases. These cases include various types of mesoscale convective systems (MCSs), supercell storms, and other isolated storms. The PI will focus analysis on two broad topics: 1. Analyze the microphysical and kinematic conditions inferred from polarimetric radar in regions surrounding where lightning is initiated, to provide clues concerning electrification mechanisms and the processes responsible for producing electric field magnitudes large enough to initiate lightning. Besides analyzing the microphysical conditions surrounding regions of initiation in typical storms and in storms with inverted polarity electrical structure, the PI will analyze cases in which lightning is initiated in anvils 50-100 km downshear from the main body of the storm and cases with steady rates of 1-4 VHF sources per second in the overshooting tops of strong isolated storms. These behaviors have been observed only recently and little is known about their characteristics and the cause of their occurrence. 2. Analyze how lightning in the stratiform precipitation region of MCSs is affected by variations in the kinematics and microphysics of systems having different modes of organization. Thus far, all published studies of in-cloud lightning structure in the stratiform region have examined leading-line, trailing-stratiform MCSs. The PI plans to analyze strongly asymmetric MCSs having a northern stratiform region formed by a mesovortex and to analyze systems with other forms of organization, to ascertain the effect of the mode of organization on lightning and charge structure. One would expect, for example, that asymmetric MCSs, which often have weaker convective cells to their north, would tend to have less lightning in the stratiform region, and that a strong mesovortex would be reflected in the structure of any lightning in the stratiform region. Data for both asymmetric and complex MCSs are ready for analysis. Broader Impacts: This project will provide research experience for three graduate students and two undergraduate students. The participation of females and under-represented minorities will be encouraged. Field programs are planned in Oklahoma during the period in which students will have the opportunity to participate and to learn skills involved in making storm observations. Much of the knowledge gained from the research will help efforts to develop applications of lightning data for weather operations, in preparation for the launch of an optical lightning mapper on the GOES-R satellite.