Comparative Study on Lightning Data between the Fengyun-4A Satellite and the National Lightning Monitoring Network in Guizhou, China

Abstract

Clustered data from the Lightning Mapping Imager (LMI) onboard the Fengyun-4A satellite were compared with lightning strike data from the National Lightning Monitoring Network (NLMN) for the period of 22 June–21 September 2020 over Guizhou Province, China. Spatial and temporal distributions of lightning counts for LMI and NLMN were mostly consistent, although the NMLN detected approximately ten times more lightning per hour than LMI. Influenced by background solar radiation, LMI data exhibited strong diurnal variations in lightning radiance, with significantly higher values during daytime. In contrast, NLMN lightning peak currents showed no similar variations. While no clear relationship was observed between the spatial distributions of LMI lightning density and radiance, a negative correlation was found between NLMN lightning density and peak current. Additionally, the matching rate (MR) for LMI and NLMN data, dependent on spatiotemporal matching criteria, was analyzed. The MR increased sharply with the extension of the temporal interval up to 2 s, then stabilized for longer intervals. In contrast, the MR was strongly influenced by the spatial matching grid cell size. For instance, within a 2-s temporal interval, an MR of 81.1% was estimated for NLMN data within a 27.5-km radius, compared to an MR of 79.8% for LMIG data within a 42.5-km radius. Furthermore, the MR was consistently higher for NLMN compared to LMI. Finally, using Bayes' theorem, we conducted a preliminary assessment of LMI's conditional detection efficiency, employing NLMN lightning data as prior information. The LMI detection efficiency was found to be significantly higher during nighttime than daytime, with values of 50.06% and 100% for daytime and nighttime detections, respectively, within a 2-s temporal interval and a 37.5-km grid cell.