Observations on the leader-return stroke of cloud-to-ground lightning with the broadband interferometer |
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Authors: | Email author" target="_blank">Wansheng?DongEmail author Xinsheng?Liu Yijun?Zhang Guangshu?Zhang |
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Institution: | 1. Cold and Arid Regions Environmental & Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China;School of Electrical Engineering, Wuhan University, Wuhan 430072, China 2. Cold and Arid Regions Environmental & Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China |
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Abstract: | Radio frequency observations of cloud-to-ground lightning (CG) were made in 1999 in Guangdong Province with the broadband
lightning interferometer. In this paper, radiation source locations and electric field waveforms are analyzed for different
types of breakdown events, including the preliminary breakdown of in-cloud activities, the stepped leaders of initial strokes
to ground and activities during and following return strokes. It is shown that the structure and development of lightning
discharges and associated breakdown processes can be reconstructed by using this new type of lightning radiation source location
system. The detectable radiation of lightning was primarily produced by the negative breakdown process. The channel was concentrated
with few branches during the preliminary breakdown stage of CG lightning flashes. The radiation sources appeared generally
at the tip of the channel. During the late period of the stepped leader, the radiation sources were dispersed with branches
extended away from the main channel. The radiation sources were in a certain length segment of the channel and the altitude
of the segment descended along with the propagation of the leader to the ground. During the preliminary breakdown and the
stepped leader of initial strokes to the ground, a sequence of fast negative streamers were observed to start continually
from or farther away the lightning-initiated region and propagate along the developed leader channel, which may supply negative
charge that assisted the leader’s development. The progression speed of fast negative streamers was about ten times faster
than the average speed of lightning channel. |
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Keywords: | broadband interferometer cloud-to-ground lightning preliminary breakdown stepped leader |
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