Three-Dimensional Lightning Positioning in Low-Frequency Band Using Time Reversal in Frequency Domain

A low-frequency lightning location system was established and operated. The time-reversal approach in the frequency domain (TRFD) is applied to the system for three-dimensional (3-D) lightning source location finding. The TRFD method uses back propagation of the signals detected at each site and determines the source location automatically using the focusing point of the back-propagated waves. Three cases are reported to showcase the capability of the method. The first case is the 3-D localization of an intra-cloud flash over the network. Both TRFD and time-of-arrival (TOA) method provide LF lightning sources that are in consistent with very high frequency (VHF) sources. The lightning sources located by TRFD method reveal more details and are more continuous compared to those obtained by TOA method used in this paper. The second case concerns the localization of an artificially triggered lightning flash with a horizontal error of 30 m by TRFD. The third case is a multi-stroke cloud-to-ground flash that shows location differences between four return strokes (RSs) being less than 60 m. Furthermore, a special case was used to demonstrate the ability of the proposed method in locating RS grounding points by combining two successive RSs when the TOA is not available.