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
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.
