Simulation and Analysis of GOES-R Geostationary Lightning Mapper Detection Algorithm Performance

The Geostationary Lightning Mapper (GLM) will be the first lightning sensor to fly in geostationary orbit. Before being launched on the Geostationary Operational Environmental Satellite (GOES) R-series in 2015, it needs to be verified that GLM can detect at least 70% of lightning flashes with a false alarm rate less than 1 false flash per second. A simulation of the two principal algorithms proposed to process the GLM data, a threshold filter onboard GLM and a coherency filter on the ground, was coded in MATLAB. The simulation was then tested with simulated lightning and shot noise modeled on statistics from the Tropical Rainfall Measurement Mission's (TRMM) Lightning Imaging Sensor (LIS).

The simulated false events only included electronic noise and background shot noise – the effects of radiation, CCD charge transfer efficiency, spacecraft jitter, and glint were not considered in this analysis. The test data contained an average of 40,000 false events per second. Threshold filter simulation involved mapping simulated event coordinates to a GOES image and using the background signal to determine threshold levels per event. The coherency filter simulation involved testing the spatial, temporal, and maximum false probability relations between events on a frame-by-frame basis to categorize events as coherent or incoherent. A worst case lightning detection rate of 74% was observed with a false alarm rate of 0.7 false flashes per second.