Lightning Evolution in Hailstorms From the Geostationary Lightning Mapper Over the Contiguous United States

Abstract

AbstractAs two metrics that depict convection features, lightning and hail are generated through different physical mechanisms but are related. The Geostationary Lightning Mapper (GLM) provides a unique approach to monitoring and studying the continual evolution of lightning in hailstorms. In this study, 3 years of GLM observations were used to analyze the lightning evolution in hailstorms over the contiguous United States. The lightning rate had two peaks at −2 min (t1) (relative to the hail occurrence time) and 59 min (t3), with a valley at 23 min (t2). The lightning rates of large hail were lower at t1 and higher at t2 than those of small hail. The maximum lightning rate grid generally moved from northwest to southeast but suddenly moved westward around 23 min. Observations of WWLLN confirmed these results but also highlighted differences, such as the high ratio between the WWLLN and GLM lightning rates around t1 and t3. The events per flash and flash duration/area/energy showed opposite variations with lightning rate, and their low values were accompanied by high lightning rate and low detection efficiency of GLM relative to WWLLN. However, the event energy continued to decrease with two local maxima at approximately t1 and t3. Furthermore, if the regional event rate was used in the lightning jump (LJ) algorithm, LJs preceded 71% of the hail reports, and the mean lead time reached 29 min. These results provide new insights into lightning features in hailstorms and verify the performance of the GLM in studying and monitoring hailstorms.