Matching algorithms of ELF-LEMPs and lightning geo-location data

ELF-band lightning electromagnetic pulses (ELF-LEMPs) have been used to retrieve lightning Charge Moment Change (CMC) and electric Current Waveform (CW). Since neither CMC nor CW can be measured by conventional Lightning Location System (LLS), it is advantageous to combine LLS and ELF measurements in order to monitor lightning geo-locations, CMC and CW simultaneously. To construct an accurate combined system of LLS and ELF measurements matching algorithms for associating lightning geo-locations and their corresponding ELF-LEMPs are important. This study developed three matching algorithms based on the time, the polarity and the direction of lightning discharges. Furthermore, we applied the newly developed algorithms to LLS and ELF measurements in Tohoku district and obtained a 30-70% Detection Efficiency (DE). The results also indicate that DE depends mainly on peak electric current (I_p). For example, DE exceeds 70% for lightning events with |I_p| ≥ 40 kA while DE drops below 70% for lower I_p events.