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Locating Preliminary Breakdown Pulses in Positive Cloud‐to‐Ground Lightning
Author(s) -
Wu Ting,
Wang Daohong,
Takagi Nobuyuki
Publication year - 2018
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd028716
Subject(s) - lightning (connector) , polarity (international relations) , pulse (music) , physics , polarity symbols , geology , meteorology , optics , chemistry , voltage , power (physics) , biochemistry , breakdown voltage , quantum mechanics , detector , cell
This paper provides the first concrete evidence that preliminary breakdown (PB) pulses of either polarity in positive cloud‐to‐ground (+CG) lightning are produced by negative leaders. Three‐dimensional location results of PB pulses in 46 +CG flashes are analyzed. The majority (40) of the +CG flashes started with positive PB pulses (+PBPs), the same polarity as the positive return stroke. Location results showed that +PBPs were produced by leaders propagating upward, which were determined to be negative leaders based on PB pulse polarities. Similarly, for the negative PB pulses (−PBPs) found in six +CG flashes, location results showed that they were produced by leaders propagating downward, and we determined that these were also negative leaders. Upward negative leaders producing +PBPs in +CG lightning are very similar to those in intracloud lightning. They usually propagate upward before turning in a horizontal direction. Downward negative leaders producing −PBPs in +CG lightning are more complicated. They usually move back upward after a period of downward propagation. Positive leaders could not be detected, but their possible propagations are analyzed along with possible charge structures for different types of PB pulses. We also demonstrate that PB pulse studies based on single‐site records are potentially unreliable.