Characteristics of current pulses in rocket-triggered lightning

Abstract

The waveform parameters of current pulses in negative rocket-triggered lightning are analyzed statistically using recorded channel-base current during Shandong Artificially Triggered Lightning Experiment (SHATLE) from 2005 to 2011. The current pulses are divided into 3 categories, including return strokes, ICC pulses in initial continuous current (ICC) stage and M-components superimposed on the continuing current following the return stroke. The geometric mean values (GM) of peak current, risetime from 10% to 90% peak, half peak width and charge transfer for return strokes are 12.1kA, 1.0μs, 14.8μs, and 0.86C, respectively. The corresponding parameters for ICC pulses are 0.09kA, 437μs, 712μs, and 0.10C, respectively, while they are 0.28kA, 251μs, 242μs and 0.10C for M-components, respectively. There is significant fraction of larger M-components (about 10% of 63 samples) demonstrating peak current of several kilo-amperes, comparable to weak return strokes. The ICC pulses show somewhat lower current peak and slower risetime than the M-components with a difference of roughly 2–3 times, resulting from the lower charge source of ICC pulses. In general, the ICC pulses and M-components show smaller peak current and charge transfer while longer risetime and half peak width than return strokes, differing with 1–2 orders of magnitude. The charge neutralized by an individual triggered lightning flash ranged from 6.3C to 68.1C, while the initial stage (IS), lasted about 245ms (GM) and lowered a GM charge of 21.2C to the ground. The average IS current in an individual lightning discharge varies from 45.8A to 140.6A with a GM value of 86.7A.