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Simultaneous observations of electric field changes, wideband magnetic field pulses, and VHF emissions associated with K processes in lightning discharges
Author(s) -
Zhu Baoyou,
Zhou Helin,
Thottappillil Rajeev,
Rakov Vladimir A.
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd021006
Subject(s) - microsecond , lightning (connector) , electric field , amplitude , thunderstorm , pulse (music) , magnetic field , physics , computational physics , atomic physics , optics , meteorology , power (physics) , quantum mechanics , detector
We studied simultaneous electric field changes, microsecond‐scale (VLF/LF) magnetic field pulses, and VHF emissions associated with K processes in 37 cloud and 54 cloud‐to‐ground lightning flashes that occurred in a local convective thunderstorm in Shanghai. All the observed features were very similar for both types of flashes. Over 98% of the 1252 observed K changes were associated with detectable microsecond‐scale pulses, although only about 26% of them were accompanied by large pulses whose amplitude exceeds by at least 50% the average amplitude of the five largest pulses in the flash. VHF bursts, which almost always coincide in time with microsecond‐scale pulses, can occur either during K changes or during the gaps between K changes. About 9% of K changes were observed to be associated with regular pulse trains, with pulses in the train showing one‐to‐one correspondence to VHF bursts and occurring at a geometric mean interval of 6.9 µs. Overall, our results indicate that small microsecond‐scale pulses are an inherent feature of K processes. We infer that the K process can be viewed as a fast negative leader, but only those leaders with appreciable charge transfer show step/ramp‐like K changes in electric field records.