A Brief History of the GOES-R Geostationary Lightning Mapper (GLM) (Invited Presentation)

The Geostationary Operational Environmental Satellite (GOES-R) series provides the continuity for the existing GOES system currently operating over the Western Hemisphere. The Geostationary Lightning Mapper (GLM) represents advancement over current GOES by providing an entirely new operational capability for total lightning detection (cloud and cloud-to-ground flashes) over the Americas and adjacent oceanic regions. The GLM will map total lightning continuously day and night with near-uniform spatial resolution of 8 km with a product latency of less than 20 sec. As a result of the Thunderstorm Project in the late 1940s and subsequent studies over the next 60 years it was established that the total lightning activity was highly coupled with the kinematic and microphysical properties and evolution of thunderstorms, and that a greater fraction of in-cloud lightning was associated with the deeper and more intense storms. The development of the GLM optical space-based instrument concept began in the late 1970s, accompanied since the early 1980s with NASA high altitude aircraft overflights of thunderstorms to characterize the sub-millisecond optical and electrical properties of lightning. The results of these studies established the feasibility of observing the optical pulses produced by in-cloud and cloud-ground-lightning from space. The major technical challenge for quantitative and useful lightning detection from space was to detect lightning during the daytime against a bright sunlit background. Temporal, spectral, and spatial filtering methods were developed that would allow lightning detection with storm-scale resolution during daytime. This approach was used in the global survey of total lightning by the Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (1997-2015). The TRMM LIS concept provided the historical basis for the GLM instrument concept in parallel with the research and pre-operational product demonstrations with forecasters that will allow the use of GLM as soon as possible after the planned launch and check-out of GOES-R in 2016. This focus of this presentation will be on the scientific and technical advances that made the GLM possible.