Variability of Lightning-Reflectivity Relationship Over Different Parts of the United States and Adjacent Ocean Areas

Weather radar data provide powerful information about storm detection, evolution and tracking. However, large parts of the Earth are not covered by weather radars, such as the oceans, mountains, and less developed areas. High-quality global lightning data can be used to detect, track, and monitor convective storms in conjunction with radar data or when radar data are unavailable. Previous studies have shown that lightning and radar reflectivity rates are correlated and this relationship can be utilized to monitor storms using a more conventional reflectivity instead of lightning density. Also, the relationship can be used in numerical models to assimilate lightning data instead of or in addition to radar reflectivity.

In this study, the relationships between lightning and radar reflectivity were investigated using lightning data from Vaisala’s GLD360 (Global Lightning Dataset). Data from 2014-2015 were reprocessed using the latest production location algorithm that has improved the location accuracy (now >80%) and detection efficiency (2-3 km). Lightning data were compared to radar reflectivity data from Unisys radar mosaics over CONUS and its several subdomains.

The results revealed a strong log-normal relationship between the lightning rates and reflectivity values. There were some interesting differences in those relationships between the subdomains that are likely related to different types of weather systems over various climate regimes across the Unites States. For example, the reflectivity values over the northwestern U.S. are generally lower than over the eastern parts of the country and the Northwest is missing high lightning-rate storms.