长春地区对流云起电过程的数值模拟

A Numerical Simulation of Electrification inside Convective Clouds in Changchun

摘要:

在三维强风暴动力和电耦合数值模式的基础上,考虑了粒子直径及降落末速差对转移电荷的影响,把非感应起电参数化方案作了进一步改进,对长春地区两次不同强度、不同环境风切变的对流云内电荷累积和电场发展过程进行了模拟分析。结果表明,对流云上升气流达到极大值时,较强和较弱两块云分别具有三极性和反偶极性电荷分布结构。垂直上升气流是表明电场发展强弱的重要参量。对发展强烈的对流云,较强的上升气流使霰和冰晶在云体的中上部维持较长的时间,存在感应和非感应起电的跃增。

Abstract:

Charges accumulation and electric field development within two convective clouds which had different degree of convection and wind shear in Changchun were simulated by introducing an improved noninductive charging mechanism including the influence of particle diameters and impact velocity into the three-dimensional dynamics and electrification coupled model.The numerical results show that tripolar structures are produced when the updraft velocity reaches the maximum value for the strongly-developed cloud,and an inverted dipole for the other cloud.Updraft is an important parameter reflecting the development of electric field.For the strongly-developed convective cloud,there are rapid rises of inductive and noninductive charging rates as a result of large amounts of graupel and ice crystals in the middle and upper part of the cloud due to stronger updraft velocity.