The three-dimensional spatial and temporal development of impulsive VHF radiation events during lightning discharges has been analyzed based on the data measured by the lightning mapping array (LMA) system with high s...The three-dimensional spatial and temporal development of impulsive VHF radiation events during lightning discharges has been analyzed based on the data measured by the lightning mapping array (LMA) system with high space and time resolution. The results indicate that intracloud discharges in the thunderstorm with a normal tripole charge structure occur not only between the upper positive and middle main negative charge region, but also with inverted polarity between the lower positive and middle main negative charge region. The polarity-inverted discharge originates from the middle negative charge and propagates downward to the lower positive region, where then the discharge develops horizontally. The characteristics of the discharge are similar to that of normal intracloud discharge except the polarity opposite. The results further confirmed the existence of the lower positive charge region involved in the lightning discharge. It was also found that the inverted charge structure opposite to the展开更多
The three-dimensional temporal and spatial characteristics of VHF radiation events produced by light-ning discharges in three supercell thunderstorms have been analyzed based on the data measured by the lightning map-...The three-dimensional temporal and spatial characteristics of VHF radiation events produced by light-ning discharges in three supercell thunderstorms have been analyzed based on the data measured by the lightning map-ping array system with high time and space resolution. The results indicate that lightning hole (lighting free region) with about 5—6 km in diameter or lighting ring (annular lighting free region) is associated with the strong updraft in thunder-storm. The lasting time of lightning holes is either short or long, being about 20 min in a tornado-producing thunder-storm. The lightning holes appear before the occurrence of tornado. The lightning hole is the most obvious during the occurrence of tornado and some self-existent lighting radia-tion events appear at a height of 15—16 km. The lightning channels of inter-cloud (IC) lightning discharge exhibit clockwise rotary structures and do not have clear bilevel structures in the vicinity of the tornado. The lightning holes are corresponding to the strong updraft region. The tempo-ral and spatial distribution of lightning radiation events re-veals the structure of strong updraft in supercell thunder-storms. Positive cloud-to-ground (CG) lightning discharges dominate in these thunderstorms and the peak of positive CG lightning flash rate appears, with the maximum of 6 per minute, after or before the occurrence of tornado.展开更多
基金This work was supported by the Chinese Academy of Sciences (Grant No. KZCX2-201) the National Natural Science Foundation of China (Grant No. 49975003)the Key Project (Grant No. 40135010).
文摘The three-dimensional spatial and temporal development of impulsive VHF radiation events during lightning discharges has been analyzed based on the data measured by the lightning mapping array (LMA) system with high space and time resolution. The results indicate that intracloud discharges in the thunderstorm with a normal tripole charge structure occur not only between the upper positive and middle main negative charge region, but also with inverted polarity between the lower positive and middle main negative charge region. The polarity-inverted discharge originates from the middle negative charge and propagates downward to the lower positive region, where then the discharge develops horizontally. The characteristics of the discharge are similar to that of normal intracloud discharge except the polarity opposite. The results further confirmed the existence of the lower positive charge region involved in the lightning discharge. It was also found that the inverted charge structure opposite to the
文摘The three-dimensional temporal and spatial characteristics of VHF radiation events produced by light-ning discharges in three supercell thunderstorms have been analyzed based on the data measured by the lightning map-ping array system with high time and space resolution. The results indicate that lightning hole (lighting free region) with about 5—6 km in diameter or lighting ring (annular lighting free region) is associated with the strong updraft in thunder-storm. The lasting time of lightning holes is either short or long, being about 20 min in a tornado-producing thunder-storm. The lightning holes appear before the occurrence of tornado. The lightning hole is the most obvious during the occurrence of tornado and some self-existent lighting radia-tion events appear at a height of 15—16 km. The lightning channels of inter-cloud (IC) lightning discharge exhibit clockwise rotary structures and do not have clear bilevel structures in the vicinity of the tornado. The lightning holes are corresponding to the strong updraft region. The tempo-ral and spatial distribution of lightning radiation events re-veals the structure of strong updraft in supercell thunder-storms. Positive cloud-to-ground (CG) lightning discharges dominate in these thunderstorms and the peak of positive CG lightning flash rate appears, with the maximum of 6 per minute, after or before the occurrence of tornado.
