气溶胶对雷暴云电过程影响的数值模拟研究

本文在已有的三维雷暴云起、放电模式中加入了一种经典的气溶胶活化参数化方案,结合一次长春雷暴个例,进行了雷暴云起放电数值模拟试验.研究显示气溶胶浓度改变对雷暴云微物理、起电及放电过程都有重要影响.结果表明:(1)污染型雷暴云中气溶胶浓度增加时,云滴数目增多,上升风速加强;云中冰晶与霰粒子数浓度增加但尺度减小;(2)相对于清洁型雷暴云,污染型雷暴云非感应起电过程弱,感应起电过程强,起电持续时间长;(3)污染型雷暴云中首次放电时间延迟,闪电持续发生的时间长,总闪电频次增加,正地闪频次增加明显.

A numerical study of the effects of aerosol on electrification and lightning discharges during thunderstorms

Numerical simulations are carried out to investigate the effects of aerosol on microphysical, electrification and lightning frequency in thunderstorm clouds. A three-dimensional (3-D) cumulus model with electrification and lightning process is used to reveal the difference of electrification and lightning process between cleaned and polluted thunderclouds. The 3-D cumulus model coupled with an aerosol module is used to simulate a case of tropical convection in Changchun city. The results show that: (1) As the aerosol concentration increases in the polluted thunderclouds, the increase of the number of cloud droplets and the updraft causes the increase of ice crystal and graupel number, but the decrease of the scale. (2) Compared to the cleaned thunderclouds, the non-inductive charging rate decreases slightly, while the inductive electrification significantly increases and the duration of electrification becomes longer. (3) The first charge time of the polluted thunderclouds delays, but the total lightning frequency increases and duration is longer. Meanwhile, the frequency of the cloud-to-ground flash in the polluted thunderclouds increases, and the increase of the positive cloud-to-ground flash is more obvious.