1991 Volume 111 Issue 1 Pages 24-30
(1) As the LLP System calculated the current to be 2.3 times that of the true current, we adjusted it correctly.
(2) We graphed the cumulative frequency distributions curves of lightning current amplitudes for each season and polarity. The curves for negative polarity resemble a logarithmic normal distribution curve, but the curves for positive polarity don't. The current values of 50% are similar to the observed datas in Niigata.
(3) When we changed the criteria of electromagnetic field waveform of Cloud-to-Ground (CG) lightning in winter, we were able to improve the detection efficiency of the system from 40% to 70%. We found that the electromagnetic field waveforms of lightning to high structures are different from the ones of CG lightning. And before we changed the criteria, the detection efficiency in summer lightning was more than 70%.
(4) We made the detection efficiency curves for each distance and from the curves constructed lightning frequency level maps.