Similarities and Differences in Total Lightning Reporting by Two CONUS Observing Systems

Total lightning flashes (TL) refer to the composite of “cloud-to-ground” (CG) and “in-cloud” (IC) lightning discharges.  TL measurements began in the 1970s with the gradual deployment of a handful of highly localized Lightning Mapping Arrays (LMAs) across the contiguous United States (CONUS), and, in recent years, TL measurements with CONUS-wide coverage have been provided by the National Lightning Detection Network (NLDN) and the Earth Networks Total Lightning Network (ENTLN).  While measurements from LMAs are generally considered as ground truth, the quality of TL data nationwide from NLDN and ENTLN has rapidly improved such that these data are already being used (or may be considered for use) in some automated forecast product applications and warning services.  In particular, ENTLN data are presently being incorporated into experimental LAMP (Localized Aviation MOS Program) convection and TL probability and potential guidance forecasts, so it is important to understand potential impacts to product quality should a switch to NLDN TL data be necessary.  Thus, this study consists of a comparison of archived historical NLDN and ENTLN TL data over the CONUS to show similarities and differences therein.

The comparative historical samples span 04 June 2014 to 31 December 2015, wherein both NLDN and ENTLN TL data are relatively stable regarding network and data processing upgrades.  Also, the geographical domain is constrained to the CONUS boundaries and about 100 km beyond to avoid contamination from inter-provider disparities in external locations with dissimilar network coverage.  The study includes all CG and IC flashes from each source, excluding minor data gaps in either provider’s archive.  The data comparisons involve various summary flash count statistics both for the entire CONUS and eastern and western subdivisions, “climatological” flash count maps, and maps of plotted flashes for selected cases.

Preliminary results show NLDN and ENTLN CG data are quite similar, with minor disparities CONUS-wide and within eastern and western subdivisions.  For IC flashes, on the other hand, disparities are quite large, with ENTLN generally reporting several times more IC flashes than NLDN.  Nevertheless, the geographical distribution of both CG and IC flashes is found to be generally similar across the two TL datasets.  In the conference presentation findings will be shown with comparative statistics, climatological maps, and individual case examinations.