May 22 - July 28
Investigation of Lightning and Storm Electrification Processes Using a Phased Array Radar and Lightning Mapping Array
Cory Schultz, David Schvartzman, David Bodine, Vanna Chmielewski, Tian-You Yu, and Michael Stock
What is already known:
- Specific Differential Phase (KDP) can show regions of ice crystal alignment due to electric field build-up and breakdown between lightning flashes
- Operational radars might sample a volume in 5 minutes, during which hundreds of flashes may happen
- Ice crystal alignment evolution within thunderstorms is difficult to capture due to the difference in temporal scales
- Phased array radars (PARs) can scan a storm volume in seconds, and Lightning mapping arrays (LMAs) constantly monitor lightning in three spatial dimensions and time
- In some instances, rapid scanning radars with LMA data have successfully captured electrified regions where ice crystal alignment occurs
What this study adds:
- From 11 May 2023 at 23:38:29 to 12 May 2023 at 00:56 UTC, Differential Reflectivity (ZDR) shows some promise in signaling regions favorable for lightning propagation, but little variation in KDP corresponded with lightning flashes
- OKLMA provided a very detailed three-dimensional map of the storm’s flash propagation and intensity, detecting 22,351 flashes around Horus’ 2,138 RHIs
- Potential future research hypotheses involving PARs, LMAs, and what effect flash rates frequency and position have on ice crystal alignment
Abstract:
Ice crystal alignment within thunderstorms is difficult to capture due to the temporal scale at which electrical build-up and breakdown occur. This study focuses on three principal objectives which include: determining how effective phased array radars (PARs) higher temporal resolution is at analyzing ice crystal alignment within thunderstorms, determining a correlation between Specific Differential Phase (KDP) and Differential Reflectivity (ZDR) signatures and the three-dimensional flash locations determined by a lightning mapping array (LMA), and finally, advancing our understanding of electrification signatures and how important the temporal scale is to the process. The fully digital polarimetric rotating S-band PAR system, Horus, conducted a series of range-height indicator (RHI) scans of a tornadic supercell on 11 May 2023 at 23:38 to 12 May 2023 at 00:56 UTC, within range of the Oklahoma LMA (OKLMA). Plotting these RHI scans along with the OKLMA data allowed for the examination of regions of negative KDP or near-zero ZDR values, which may correspond to vertical ice crystal alignment in large electric fields. In the end, Horus’s KDP signatures did not align with the lightning flashes in this case, but many flashes were in areas with near-zero ZDR values. The storm was very electrified with 22,351 flashes occurring during the study period with 2,138 RHI scans, potentially beyond the point that 2-second RHI scans can capture storm electrification and the process of ice crystal alignment.