Abstract:
Electric field pulse bursts generated by lightning
flashes are considered as sources of high radio frequencies. In
this study, an analysis of pulse bursts in electric field records of
30 negative cloud to ground lightning flashes recorded in the
southern coastal area of Sri Lanka is presented. Sixty-four
percent (64%) of pulse bursts are typical chaotic pulse trains
(CPT). Twenty-four percent (24%) of pulse bursts exhibit CPT
characteristic while containing regular pulses within the burst.
These are termed as “semi-regular pulse bursts” in this study.
The regular pulses within CPTs show characteristics similar to
dart stepped leaders or stepped leaders, and in some cases, more
than one regular pulse trains with different characteristics are
observed within a single burst. The intra-cloud lightning
activities associated with CPT such as K changes, leader
processes, and isolated pulses bursts also exhibit regular pulse
bursts or semi-regular pulse bursts. CPT and regular pulse trains
always show similarity in occurrence, and semi-regular pulses
have the characteristic of both type of pulse bursts. Hence CPT
and semi-regular pulse bursts may be formed by superposition of
two or more regular pulse bursts which represent dart stepped
leader or stepped leader type activities
