A New Approach To Map Lightning Channels Based On Low-Frequency Interferometry

A purely interferometric algorithm, named imaging algorithm, has been developed for mapping lightning in the low-frequency band. The imaging algorithm locates a lightning source by computing the three-dimensional correlation of the lightning signals arriving at a pair of lightning sensors, and then summing the correlations of all antenna pairs. This algorithm does not locate the source by solving the non-linear time-of-arrival (TOA) equations, instead the source is located at the global maxima of the total correlation. The lightning map produced by the imaging algorithm for one intracloud flash was compared with that of the hybrid interferometric-TOA algorithm. The imaging algorithm can locate more sources than the hybrid algorithm and produce more complete lightning maps. We also demonstrated that the imaging algorithm can locate multiple concurrent lightning sources even though the recorded signals from the pulses overlap in time at some stations, which is not possible with a traditional TOA-based technique.