Future Lightning Instruments for Weather and Climate Monitoring From LEO
Lightning is not only a natural hazard, but it also holds information about physical processes at work in deep convection and influences atmospheric oxidants that modulate ozone and methane. Hence, spaceborne lightning observations are essential for monitoring extreme events and feedbacks in Earth’s climate system. Low-Earth orbiting (LEO) lightning mapping instruments established a 25-year record of global lightning activity and resulted in a wealth of studies that motivated its designation as an Essential Climate Variable by the World Meteorological Organization. Although geostationary observations of lightning have become increasingly available since 2017, LEO lightning mappers continue to serve critical needs given their unique vantage point and acceptance as a unifying reference for geostationary lightning mapper and ground-based global lightning datasets. At the close of 2023, the Lightning Imaging Sensor (LIS) will cease operations on the International Space Station, which introduces a critical gap in LEO-based monitoring of global lightning activity. To address this need, NASA is developing new lightning mapping technology that enables future LEO-based satellite missions. Existing LEO-based lightning mappers rely on narrowband optical emissions centered on 777.4-nm and detectors that capture 500 images per second to detect lightning both day and night. Lightning can also produce optical emissions in a narrowband centered on 337-nm without any corresponding emissions at the traditionally used near-infrared (NIR) wavelength. These near-ultraviolet (UV) emissions are associated with earlier stage electrical breakdown (e.g., streamers), may frequent intense regions of deep convective storms, and may be a significant source of nitrogen oxide production in the upper atmosphere. A new lightning mapping instrument called the CubeSat Lightning Imaging and Detection Experiment (CLIDE) is being designed at NASA Marshall Space Flight Center to use high-speed, scientific CMOS image sensors capable of detecting lightning’s transient optical emissions in the near-UV and NIR during both daylit and nighttime scenes. This will extend the record of global lightning activity and help pave the way for future small satellite missions that combine radio and optical lightning detectors to obtain novel three-dimensional maps of lightning on a global scale, which can revolutionize the way lightning is used to monitor weather and understand changes in climate.