A Case Study on Characteristics of Lightning Activity in a Mesoscale Convective System
Guili Feng, Xiushu Qie, Yunjun Zhou · Gaoyuan qixiang · 2006
The evolution of cloud-to-ground(CG) lightning in a typical mesoscale convective system(MCS) was analyzed by using the data from lightning detection system,Doppler radar and satellite.The result shows that almost all the CG flashes are negative at the first developing stage.The CG flash rate is high(more than 10 min~(-1)) and negative CG flash predominatesalong the mature stage of the storm.The CG flash rate declines rapidly with the increase of positive CG lightning ratio at dissipating stage.The CG flashes mainly occur in the region with the temperature less than-50℃ and high temperature gradient in the front of MCS,but there is no CG flash in the cloud with temperature higher than-30℃.Negative CG flashes cluster in the intense echo(40 dBz) region and its duration coincidenceswith the strong convection,which suggests that the negative CG flash could be used to indicate the strong convective region.Moreover,the dense positive CG flashes can also be observed in the strong echo region,while sparse ones are in the weak and stable echo region or cloud anvil in the rear MCS.The data analysis also shows that the high positive CG flash rate could correspond to a damaging weather.The advent of high positive CG flash rate should be paid more attention in nowcasting of severe convective weather.