An In-Depth Analysis Of Lightning Trends In Hurricane Harvey Using Satellite And Ground-Based Measurements

Satellite lightning measurements from the Geostationary Lightning Mapper (GLM) and ground-based measurements from Earth Networks Total Lightning Network (ENTLN) for Hurricane Harvey (2017) are combined to obtain a better representation of intra-cloud and cloud-to-ground lightning and their relationship to intensification and weakening of the hurricane. Through this combination, detection efficiencies of ENTLN and GLM are calculated for the rainband and eyewall of Harvey. In addition, the combined data set is used to derive the cloud flash fraction (CFF) and cloud pulse fraction (CPF) throughout the study period. The results show that flash and pulse rates increase in both the eyewall and rainband prior to rapid intensification in Harvey. The rainband lightning has the highest correlation to Harvey's intensification, where increases in lightning correspond to the largest periods of wind-speed intensification. The eyewall CFF is also highly correlated to intensification, with minima in eyewall CFF and CPF coinciding with slower intensification periods in Harvey, while increasing CFF and CPF corresponds to more rapidly intensifying periods. Further, GLM flash characteristics including the events per flash, groups per flash, maximum group area, maximum number of events per group, flash footprint, flash energy, and flash duration are tracked and compared to Harvey's wind-speeds. Nearly all seven flash characteristics show an increase prior to rapid intensification, with the strongest correlation to intensification found with the rainband lightning spatial characteristics. This research represents a step forward in the application of lightning data that can be used in future studies of tropical cyclone intensification and weakening.