Simultaneously measured current, luminosity, and electric field pulses in a rocket-triggered lightning flash

Abstract

[1] Current, luminosity, and electric field pulses in a rocket-triggered negative lightning flash have been analyzed based on the channel base current, high-speed video images, and electric field changes at 30 m from the channel. Among the 31 distinct current pulses, there are 4 return strokes, 18 typical M components, 5 large M components with unusual large peak current in a range of kiloamperes, 3 initial continuing current (ICC) pulses, and 1 stroke-M component (RM) event which exhibits both return stroke and M component features. The geometric mean of peak current is 13.5 kA, half peak width is 28.4 ms, and risetime from 10% to 90% peak is 1.1 ms for the 4 return strokes, while the corresponding values are 243 A, 400 ms, and 319 ms, respectively, for the 18 typical M components and 5.1 kA, 76.3 ms, and 34.6 ms, respectively, for the 5 large M components. The electric field and current waveforms of ICC pulses exhibit features similar to those of the M components, indicating the similarity of their mechanisms. Detectable optical luminosity is found just prior to all the pulse events, even return strokes. The M components are superimposed on a slowly varying continuing current, while the directly measured current prior to the return stroke is not significant. The simultaneous electric field and current waveform of RM implies a superposition of dart leader and M incident wave in the channel, and the possible reason is that two branches with common lower portions coexist simultaneously in the upper part of the discharge channel.

Lightning leader stepping, K changes, and other observations near an intracloud flash

“…Although the behavior of positive leaders inside clouds is not well documented, they have been observed many times below cloud base in lightning flashes that propagate upward from tall towers and from rocket‐triggered lightning [ Rakov and Uman , 2003; Flache et al , 2008; Qie et al , 2011]. They sometimes propagate smoothly and at other times as a sequence of sudden steps with pauses of about 20 μ s between each step [ Idone , 1992].…”

High resolution observation on rocket-triggered lightning

“…The risetime from 10% to 90% of the first peak is 5.0 ms and from 10% to 90% of the total peak is 27.8 ms. The possible reason for RM process is that two branches with common lower portions co-exist simultaneously in the upper part of the discharge channel [9]. Half Peak Width (ms) Charge Transfer (C) Figure 5.…”

Validation and revision of far-field-current relationship for the lightning strike to electrically short objects

“…Expressions relating radiated fields and return stroke channel base currents have been derived for various "engineering" return stroke models (Rakov and Uman, 1998 ). Based on the transmission line (TL) model, for an observation point at ground level, the radiated (far) electric and magnetic fields produced by a vertical lightning channel terminated directly at ground are simply proportional to the channel base current (Uman et al, 1975;Qie et al, 2007Qie et al, , 2009Qie et al, , 2011Yang et al, 2010), with the proportionality coefficient being determined for strike to flat ground with the perfect conductivity.…”