A novel algorithm for determining lightning leader time onset from electric field records and its application for lightning channel height calculations

Abstract

Estimation of the lightning channel height was done on the basis of detected lightning stepped leader stage. The stepped leader time onset, and then the leader duration, were identified from ELF-MF lightning electric field signatures obtained from the local lightning detection station operating in the city of Rzeszów, Poland. The particular lightning stepped leader stage duration and evaluation of the lightning channel height was determined from the recorded lightning electric field Power Spectrum Density spectrograms integrated with respect to the frequency domain and recalculated by the new procedure using the proposed fill factor function. Finally, estimated lightning channel height was superimposed on the relevant 3D Doppler radar reflectivity images of thundercloud in order to show how this lightning channel onset was located in relation to the main precipitation cores. The high efficiency of lightning stepped leader discrimination was obtained, especially in cases of the close ground flashes, when the electrostatic field component of lightning stepped leader stage dominates the total electric field change of the considered ground stroke. The proposed method can be implemented to different kinds of lightning location systems, increasing their detection capabilities without the need to significantly increase computing power and with low application costs.