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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