Performance Evaluation of LMI Based on Low-Frequency Three-Dimensional Total Lightning Flash Location Data

Abstract

At present, there is still some uncertainty in the evaluation of the performance of the Fengyun 4A Lightning Mapping Imager (LMI), which is mainly limited by the detection performance of the reference detection system and the suitability of the evaluation method. In this paper, a one-to-one performance evaluation of the LMI was performed based on total lightning flash data from the lightning Low-Frequency Electric field Detection Array (LFEDA). It was found that there were significant systematic biases in the discharge results detected via LMI, with a median of −0.946 s, −0.0817°, and −0.0245° in time bias, longitude bias, and latitude bias, respectively. The evaluation results after removing the systematic biases indicated that the relative detection efficiency for flashes of LMI was 17.6%, the mean and median time errors were both 0.647 s, and the mean and median distance errors were 6.09 km and 5.02 km, respectively. The relative detection efficiency for groups of LMI was 9.8%, the mean and median time errors were 0.674 s and 0.660 s, and the mean and median distance errors were 7.19 km and 6.54 km, respectively. The detection efficiency of LMI for both flashes and groups at nighttime was significantly higher than its detection efficiency during the daytime. The relative detection efficiency for flashes of LMI at nighttime was 26.5%, while during the daytime it was 14.4%. The relative detection efficiency for groups of LMI at nighttime was 16.2%, while during the daytime it was only 7.4%. The spatial accuracy for both flashes and groups was always better during the daytime than at nighttime.