Effects of Charge Redistribution after Discharges on the Charge Structure of Thunderstorms and Lightning Characteristics

To investigate the effects of charge redistribution after discharges on lightning characteristics, a threedimensional (3-D) cumulus model with electrification and lightning process is coupled with two different schemes of charge redistribution. In one scheme, i.e. the ZR scheme for short, the induced charges are added to the space charges along the lightning channel; in the other scheme, called ZH scheme for short, the charge density along the lightning channel is reduced by a certain percentage. Sensitivity experiments are performed using the sounding data collected at Changchun. Obvious differences between the lightning characteristics are found using the above two different ways of charge redistribution. The results show that:1) The intra-cloud flash rate in the ZR scheme is less than that in the ZH scheme. Charges with opposite polarity are embedded in the charge region, and more charges are neutralized in the ZR scheme than in the ZH scheme, which causes the electric field in the ZR scheme to drop more sharply. 2) The positive and negative cloud-to-groundflash rates in ZR scheme both are higher than that in the ZH scheme. Compared with that in the ZH scheme, the distribution range of the positive charge region is larger than the lower negative charge region, leading to a higher positive cloud-to-ground flash rate in the ZR scheme than that in the ZH scheme. Meanwhile, the degree of mixing of the shielding charge region at the cloud top with the positive charge region is stronger and the time of mixing is longer in the ZR scheme, thereby more negative cloud-to-ground flashes initiated between the positive charge region and the lower negative charge region are triggered in the ZR scheme. 3) The lightning channel length in the ZR scheme is shorter than that in the ZH scheme. Charges with opposite polarity are embedded in the charge region, and it is difficult to form large charge regions with the same polarity. The transmission of the lightning channel is limited to a couple of small charge regions with opposite polarity in the ZR scheme. However, the distribution of the charge regions in the ZH scheme does not change and there are large charge regions with the same polarity, while the range of the transmission of the lightning channel is also larger.