Thunderstorm Electrification and Kinematics As Seen Through Ensemble Lightning Flash Properties
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Tuesday, 4 November 2014: 2:15 PM
University (Madison Concourse Hotel)
This study compares local, three-dimensional flash rate and flash size statistics to storm structure in an attempt to better understand how the local kinematic properties of the thunderstorm influences these characteristics. Charge in a thunderstorm is carried on hydrometeors within updrafts and downdrafts, coupling net charge separation and electric field formation to the storm's kinematic properties. Turbulent eddies are expected in or near strong updrafts, with more uniform flow on the periphery of the storm, which argues for smaller and more frequent flashes in and near the updraft, and larger, less frequent flashes away from the updraft. Previous studies have noted these flash tendencies. This study investigates them for the first time using three-dimensional flash grids derived from Lightning Mapping Arrays in Oklahoma and West Texas for a variety of storm modes. For supercells, differences were observed between left and right movers, with maximum flash rates and smallest flash sizes collocated with the preferred updraft locations for each mode. In both MCSs and supercells convectively active regions had smaller and more frequent flashes than more stratified regions.
This coupling between storm kinematics and ensemble flashes allows for the application of lightning information in warning decision support as the lightning data provides qualitative information about storm dynamics when quantitative information is not available. Such information would also be useful to forecasters trying to assess changes in storm dynamics that may not be immediately obvious through radar data alone, such as changes to initiation locations signifying new updraft cores or changes to the flash size distribution indicating maturing or decaying cells.