Characterization of Lightning Flash, Kinematic, and Microphysical Properties within the 22 April 2017 Tornadic Skyline, AL Supercell

The detection and mapping of lightning from space has been around since the mid-1990s with the NASA Optical Transient Detector and TRMM Lightning Imaging Sensor. However, the launch of the Geostationary Lightning Mapper (GLM) in 2016 ushered in a new era of space-borne lightning measurements, allowing for the capability to use lightning in the operational community, while improving the usage of lightning data to the scientific community. As with any new instrument, understanding how these observations relate to previous knowledge is imperative. One parameter that GLM provides and has not been heavily investigated is the total optical energy and its relation to a storm’s updraft. The results of Conrad et al. 2019 showed that a direct relationship between the storm’s updraft and the total optical energy may not exist, however, inferences about the storm’s updraft by using optical energy in tandem with other remotely sensed information may be possible. Conrad et al. 2019 also showed that trends in the flash rates between the LMA and GLM also differed in relation to the storm’s updraft. It was hypothesized that as a storm’s updraft increased in size and magnitude, a decrease in the optical energy would be observed.

This study will focus on individual flashes to support some of the hypotheses set forth in Conrad et al. 2019. Analysis of individual flashes will be performed at different phases of the supercell’s life-cycle (intensifying, mature, weakening, etc.) to characterize how changes in the storm’s kinematic and microphysical properties impact lightning flash properties, specifically the total optical energy. The storm of interest occurred on 22 April 2017 in northern Alabama, producing copious amounts of severe hail and an EF-0 tornado in Skyline, AL. Data from the GOES-R Calibration/Validation and VORTEX-SE field campaigns will be used, with a specific focus placed on instruments located on the NASA ER-2 aircraft, such as the Cloud Radar System (CRS), Cloud Physics Lidar (CPL), and Fly’s Eye GLM Simulator (FEGS). Additional data from the NOAA P-3 may also be investigated. It is hypothesized that flashes with a lower optical energy measured by GLM will have a smaller Convex-Hull area, increased turbulence along the sides of the updraft, and increased cloud top height, while the inverse is expected for flashes with higher optical energy.