An improved wave impedance approach for locating close lightning stroke from single station observation and its validation

摘要

An improved wave impedance approach for locating close lightning strokes based on single station observation was proposed and practiced. In the approach, a lightning stroke was modelled with an electrical dipole carrying current components in VLF/LF frequency bands. For a lightning stroke, the ratio of its electrical and magnetic fields at ground is theoretically a function of the frequency and distance to the stroke. Distance of the stroke can then be obtained by fitting the theoretical function with the observed data. The approach was examined by applying it to broadband VLF/LF electrical and magnetic fields observed simultaneously at one station for several strokes in ranges of 10-50 km. Furthermore, a prototypal single-station lightning location system (S-LLS), which can be analogized to a modified VLF/LF broadband magnetic direction-finder programmed with the proposed lightning stroke distance determining approach, was built up and tested. Comparisons of individual stroke locations with the local lightning location network show that the S-LLS has a good location accuracy of 0.1-4 km for close strokes in ranges of 15-60 km, but has a poor location accuracy of 12.4-26 km for distant strokes in ranges of 80-130 km.