Evolution Characteristics of the Lightning and the Relation with Dynamical Structure in a Mesoscale Convective System over North China

Based on the lightning location detection data, Doppler radar data, and synoptic information, this paper presents the lightning characteristics of a typical mesoscale convective system (MCS) in the north of Shandong Province on 1 August 2005. It is found that the negative cloud-to-ground (-CG) lightning is predominant over the positive cloud-to-ground (+CG) lightning during the whole thunderstorm lifetime. At the dissipation stage, IC (intra-cloud lightning) /CG is 2∶1 within the detection range. And when the electric field changed greatly, the lightning happened frequently. The CG lightning mainly occurred in the regions with high values of convective available potential energy (CAPE) and surface equivalent potential temperature. The comparison between the location of lightning activity and radar echo shows that -CG usually clusters in the intense echo region with high reflectivity (>40 dBZ), while +CG usually disperse in the weak echo (30 dBZ－40 dBZ) region. Relation between the cloud-top brightness temperature and the CG lightning location indicates that most flashes occurred in the area with temperature lower than -40℃, while the +CG lightning clustered in the region with the cloud-top temperature between -40℃ and -50℃. The comparison between the wind field retrieved from Doppler radar and the location of CG flashes indicates that the flashes are usually located in the cyclonic shear or wind shear areas which corresponds to the intense echo. The CG flashes are easier to happen in the stage that updraft reaches the maximum and downdraft appears.