GLM: Geostationary Lightning Mapper for Early Warning of Severe Storms

The GOES-R series of geostationary weather satellites, equipped with the new Geostationary Lightning Mapper (GLM) instrument, will soon provide a new lightning mapping capability that enables improved warning times for severe weather events, decreased false alarms, persistent coverage over wide geographical areas, and long-term monitoring of trends linked to the changing climate.

Weather forecasting products based on lightning mapper data can be generated within seconds or minutes of detection, providing timely and accurate warning of severe weather including thunderstorms and tornadoes. Total lightning activity, sensed by a lightning mapper, is quantitatively related to the total ice production in a thunderstorm, which in turn is related to the total precipitation. Deep convective storms often produce very high rain rates and can result in flash floods. Lightning flash rates within individual storm cells exhibit a “jump signature” that reliably predicts tornado activity with warning times longer than 30 minutes. Lightning flash rates have also been linked to intensification of tropical cyclones, despite their low overall lightning activity.

The basic design of GLM, developed under a contract from NASA Goddard, consists of a one nanometer wide interference filter and a focal plane operating at 500 frames per second, in order to maximize the lightning signal relative to the background signal arising from sunlight reflected from the tops of thunderclouds. The same Real Time Event Processor (RTEP) event detection concepts developed for Lightning Imaging Sensor (LIS) are implemented on GLM to reduce downlink bandwidth by a factor of 1000. Using ground processing algorithms, the GLM instrument will discriminate true lightning events and flashes, and generate lightning weather products leading to more accurate and timely severe weather warnings.