Observed relationships among Narrow Bipolar Events, total lightning and convective strength in Summer 2005 Great Plains thunderstorms

Satellite-based Very High Frequency (VHF) lightning sensors are limited in sensitivity to a particular (but particularly powerful) in-cloud radio frequency (RF) pulse. Hence, the viability of global storm tracking based on satellite-based VHF sensors largely depends on whether these strong in-cloud pulses can be used as robust and generic indicators of convective strength. The RF pulses observed by satellite are sometimes accompanied by distinctive narrow electric field change pulses (called Narrow Bipolar Events or NBEs) observed by ground-based Very Low Frequency sensors such as the Los Alamos Sferic Array (LASA). A recent preliminary study compared LASA NBE flash rates to cloud-to-ground (CG) flash rates in a small geographical area in central and northern Florida. This study used CG flash rates as a proxy for convective strength, and found that NBE flash rates are proportional to CG flash rates, and, by extension, to convective strength.

Here, we extend the earlier studies, using an updated LASA in the Great Plains which covers a much larger geographical area and has improved detection efficiency of intra-cloud (IC) flashes. Instead of using CG flash rate as a proxy for convective strength, we use maximum radar reflectivity and maximum height of 30, 40, 50 dBZ radar echo as proxies for convective strength and compare these convective proxies to IC, CG, and NBE flash rates recorded by the Great Plains LASA. In addition to gridded statistical relationships of these quantities, we also present sample case studies to investigate finer-scale temporal and spatial relationships between lightning and convective development.