9.4 Flash Size Distributions Characterized by Mobile LMA Deployments During VORTEX-SE

Wednesday, 9 November 2016: 9:45 AM
Pavilion Ballroom (Hilton Portland )
Eric C. Bruning, Texas Tech Univ, Lubbock, TX; and V. C. Chmielewski, C. C. Weiss, J. Dahl, A. J. Hill, C. J. Schultz, and J. Bailey

Theoretical and observational evidence predict a drop in flash size accompanying a jump in flash rates as the charge structure in the storm’s mixed-phase region becomes more complex due to turbulent kinematics and dynamics. These findings informed TTU’s participation in the first field phase of the Verification of the Origin of Rotation in Tornadoes Experiment – Southeast (VORTEX-SE) project. In this study, we investigate in detail the 31 March 2016 VORTEX-SE case, in which a jump in lightning flash rate accompanied an increase in low-level vertical vorticity. Modulation to the flash size distribution accompanying this change is examined, with a focus on accompanying environmental heterogeneity measured by StickNet deployments on the meso- and storm-scale. We relate these findings to ongoing work as part of TTU’s Kinematic Texture and Lightning Experiment, which has quantified the flash size and rate alongside the turbulent structure of thunderclouds using high resolution Ka-band radars during field observations in 2015 and 2016.

In order to enhance the detection of the smallest lightning flashes in the turbulent portions of the thundercloud, TTU routinely deployed a mobile Lightning Mapping Array (LMA) station that was used to augment the North Alabama LMA. This is the first time an LMA station has been placed in real-time in response to the radar deployment pattern of the day. A two-person team deployed the mobile LMA station prior to the start of sounding operations from the Ballooning and Observation Lab for Thunderstorms (BOLT). Processed data with and without this additional station are compared with predicted improvements to the minimum detectable flash size using a new simulation tool, with a focus on improvements to detection of small lightning flashes.

Given our success in deploying a station from BOLT (prior to the start of sounding operations from the same vehicle) we sketch a possible deployment scheme using two to three vehicles which would enable full LMA coverage for fully nomadic field projects. 

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