Spatial and temporal evolution of a multi-cell thunderstorm charge structure in coastal areas

The spatial and temporal variations of charge structure and the relationship with intensity of radar echo of a thunderstorm in lower altitudes, Shandong of China, have been analyzed with the radiation sources of lightning discharge three-dimensional mapping system. The results indicate the charge structure was typical dipolar in the convective areas. The intensity of positive charge region was increased and the height of location was lifted with the development of thunderstorm. The negative charge region is in the area where the intensity of radar echo was more than 40 dBz and the positive charge region was in the 40 dBz radar echo area approximately. The charge structure was also inferred dipolar with low charge height and weak charge intensity in stratiform areas. In the dissipation stage of thunderstorm, the charge structure was ruptured for the different dissipation level of different part in cloud. The positive and negative charge regions sank in the front of the cloud, and the height of the positive and negative charge region changed little in the middle part of the cloud, whereas the negative charge region was attenuated. So the charge region had four layers in convective areas during dissipation stage. The above result shows that the advantage charge generation mechanism often generates dipole or tripole charge structure and does not generate multipole charge structure. This paper also analyzes a negative cloud-to-ground flash discharge process. Its charge structure is the same with the thunderstorm charge structure. So the thunderstorm charge structure can be illustrated by the observation of three-dimensional lightning mapping system.