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Characteristics of a Negative Cloud-to-Ground Lightning Discharge Based on Locations of VHF Radiation Sources

发布人:ljh  |  来自:本站  |  发布时间:2014-05-20 18:44:13  |  点击次数:1203
全文下载链接:http://lageo.iap.ac.cn/uploads/1405210246227ozaig4yaj55.pdf

Abstract  

The lightning very high frequency (VHF) radiation location system based on the short-baseline time-difference of arrival (TDOA) technique provides an effective approach to describe the temporal and spatial development of lightning discharge in two dimensions with high resolution. A negative single-stroke cloud-to-ground (CG) lightning flash was analyzed in detail using the radiation location results and synchronic fast/slow electric field changes. The long-duration preliminary breakdown process appeared to propagate with bi-directional leader channels. The two negative simultaneous discharge channels sloped down with a considerable horizontal component in the lower positive charge region at speeds of about 105 m s?1. The stepped leader was clearly converted from one channel of the preliminary breakdown process and spread downwards with branches. The speeds of the stepped leaders were about 105 m s?1. The K processes after the return stroke could either directly initiate from the start region with negative polarity lightning discharge, or initiate from a new region in the cloud as negative recoil streamers. All K processes propagated along the preceding electrified channel, while not all K processes initiated from the tips of positive breakdowns. The speeds of the K processes were about 106–107 m s?1.

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