Continuing Current Seen Above and Below the Cloud: Comparing Observations From GLM and High-Speed Video Cameras

This study assesses the reliability and limitations of the Geostationary Lightning Mapper (GLM) in detecting continuing currents by comparing observations from ground-based high-speed cameras with GLM-16 data. Our findings show that the GLM's one-group detection efficiency (DE_1) is 53%, while the more stringent five-consecutive-group detection efficiency (DE_5) is 10%. Optical signals detected by the GLM predominantly occur during the early stages of continuing currents. Additionally, there is a notable disparity in detection efficiencies between positive and negative continuing currents, with positive continuing currents being detected more frequently. The application of the logistic regression model developed by Fairman and Bitzer (2022) further illustrates the limitations in continuing current identification. The study underscores the challenges of relying solely on satellite data to monitor and analyze continuing currents, emphasizing the need for advancements in detection technologies and methodologies to reliably detect continuing current at a large spatial scale. This study investigates continuing current in cloud-to-ground lightning-a prolonged electrical discharge known for causing significant damage, such as igniting large-scale wildfires. For the first time, we used recordings from ground-based high-speed cameras to assess how effectively the Geostationary Lightning Mapper (GLM), an optical instrument on the GOES satellite, detects these currents. Our findings reveal that the GLM often captures only the early stages of continuing currents and struggles to detect them consistently, particularly those in weaker, negative types of lightning. These results underscore the limitations of current satellite-based optical instruments in fully monitoring continuing currents, emphasizing the need for improved methods to better detect and understand these electrical discharges and mitigate their impacts. The Geostationary Lightning Mapper is limited in detecting continuing current, with a one-group DE of 53% and a five-group DE of just 10% Optical signals captured by the Geostationary Lightning Mapper are predominantly during the early stage of continuing currents A significant disparity is observed in GLM detection efficiencies between positive and negative continuing currents