Characteristics of Cloud-to-Ground Lightning in Chinese Inland Plateau.

Abstract

Characteristics of cloud-to-ground (CG) lightning flashes in the Chinese inland plateau have been analyzed by using the data obtained from a broadband slow antenna system, with a time resolution of 1 microsecond in 1996, and a CG lightning location network from 1997 to 1998. It has been found that lightning discharges in a plateau summer thunderstorm usually present some special characteristics compared with the typical summer thunderstorm. On the average, positive CG flashes comprised 16% of total CG flashes in the Chinese inland plateau. After comparison with radar echo, it is found that some weak thunderstorms are conducive to positive CG flashes. The first return strokes are usually preceded by a long duration preliminary breakdown process which is characterized by discrete bipolar pulses for both positive and negative CG flashes. The mean duration of electric field change prior to first return stroke is about 126.1 ms, in which 23% exceeds 200 ms for negative CG flashes, and the corresponding value is 165.1 ms for positive CG flashes. The mean interval between 152 successive analyzed pulses is 211.0±148.0 ms, and the total duration of the pulses is 32.0±20.0 ms for negative CG flashes, while the mean time interval between the 50 analyzed pulses is 165.0±120.0 ms and the total duration of pulses is 27.0±19.0 ms for positive CG flashes. Other discharge features, such as interstroke intervals, amplitude distribution of the subsequent return strokes and etc., are also analyzed in the paper.