signature=87d3fcb5be32d54911a14c20b5fafda3,Signatures of the lightning HF radiation at 10 MHz, 5 MHz...

摘要：

Under this study, we have analyzed 46 ground flashes, which has simultaneous records of HF radiations at 10 MHz, 5 MHz and 3 MHz. For 87% flashes strongest HF radiation was observed at the beginning of the return stroke and for 13% flashes it is during the leader phase. Most of the cases, it is apparent that after the initial burst associated with the onset of the negative return strokes, the intensity of the HF radiations at 10 MHz, 5 MHz and 3 MHz increase again after several milliseconds with the range of 15 ms to 20 ms. Authors believe that this can be due to possible cloud activity. In between it is an almost idle period (15 ms to 20 ms) for all 3 HF radiation signals observed. According to the analysis based on the step function response and delta function response we can conclude that 5 MHz radiation is more dominant over 10 MHz and 3 MHz radiations observed for ground flashes. The mean duration of the HF radiation continua associated with the first return strokes is 239 s (N=46 and SD=93 s).

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