Evaluating ENTLN Performance Relative to TRMM/LIS

This study evaluates three years (2011-13) of data from the Earth Networks Total Lightning Network (ENTLN) relative to the Tropical Rainfall Measurement Mission (TRMM) Lightning Imaging Sensor (LIS). Within the Western Hemisphere (38 degrees N to 38 degrees S), the relative flash detection efficiency (DE) increases from 21.6% during 2011 to 31.4% during 2013. Performance improves in each geographical subdomain, with the best regional performance (71.9%) over the southern contiguous United States (south of 38 degrees N). The daily relative flash DE generally exceeds 15% (50%) in the Western Hemisphere (North America), but large day-to-day variability is evident. The average distance (timing) offset between matched LIS flashes and ENTLN events is 10.8 km (+25.0 ms). Although the average timing offset is positive, the ENTLN reports its first event before 48.6% of LIS flashes begin. Multiple ENTLN events occur during most matched LIS flashes, and the ENTLN defines 51.3% of all matched LIS flashes as cloud-to-ground (CG). National Lightning Detection Network data help characterize flash type [CG versus intra-cloud (IC)], allowing investigation of the LIS characteristics of IC and CG flashes. The ENTLN detects the most intense LIS flashes, and the LIS characteristics indicate that CG flashes transfer more charge than IC flashes. The maximum number of events per group and maximum group area are much larger for confirmed CG flashes (14.9 and 378.4 km(2), respectively) than for confirmed IC flashes (7.7 and 200.4 km(2), respectively).