| Title |
Characteristics of the Electromagnetic Fields Radiated from Stepped Leaders Just Prior to Lightning Return Strokes |
| Authors |
이복희 ; 이동문 ; 정동철 ; 장근철 ; 이승칠 ; 정광희 |
| Keywords |
Radiation field waveforms ; stepped leaders ; mean pulse widths at half maximum, lightning return stroke ; electromagnetic pulse |
| Abstract |
In this paper statistics on the radiation field waveforms produced by stepped leaders just prior to lightning return strokes were described. As a parameter of stepped leader pulse characteristics, the time interval between the final leader pulse and return stroke peak, the pause time between stepped leaders, the ratio of the final leader peak to the return stroke peak and the stepped leader pulse width at half maximum were examined. The average time intervals between the final leader pulse and return stroke peak were about 16.2 and 14.8mutextrm{s} for the positive and negative polarities, respectively. When the stepped leader approaches closely to ground, the time interval between leader steps was decreased and the mean value was about 17mutextrm{s}, and the present results were in reasonable agreement with the data observed in Florida and Japan. The large fraction of the ratios of the final stepped leader pulse to the lightning return stroke peak were distributed over the range from 5 to 35% and in average the ratio of the final leader pulse to the return stroke peak was 17.4 pm11.9% for the positive and 18.5 pm9.4% for the negative electric field waveforms. In addition, the mean pulse widths at half maximum of the stepped leaders are 1.4Us with a standard deviation of 0.9 for the positive Polarity and 2.2us with a standard deviation of 1.2 for the negative polarity, respectively. |