Idealized numerical simulation experiment of ice seeding in convective clouds using a bin microphysics scheme

Abstract

A 2D axisymmetric bin model is used to conduct idealized numerical experiments of cloud seeding. The simulations are performed for two clouds that differ in their initial wind shear. Results show that, although cloud seeding with an ice concentration of 1000 L−1 in a regime that has relatively high supercooled liquid water can obtain a positive effect, the rainfall enhancement seems more pronounced when the cloud develops in a wind shear environment. In no-shear environment, the change in the microphysical thermodynamic field after seeding shows that, although more graupel is produced via riming and this can increase the surface rainfall intensity, the larger drag force and cooling of melting graupel is unfavorable for the development of cloud. On the contrary, when the cloud develops in a wind shear environment, since the main downdraft is behind the direction of movement of the cloud, its negative effect on precipitation is much weaker.摘要本文采用二维轴对称分档云模式开展了人工催化数值试验, 对两种不同初始风切变的对流云进行了模拟. 结果表明, 尽管在过冷水相对较高的区域播撒 1000 L−1 的冰晶可以增加地面降水, 但当云在风切变环境中发展时, 人工播撒对降雨增强的作用似乎更加明显. 在无切变环境下, 微物理量, 热力场的变化表明播撒后大量的霰所产生的拖曳力和融化冷却有可能切断主上升气流, 从而不利于云的发展. 相反, 当云在风切变环境中发展时, 由于播撒产生的主下沉气流位于云的运动方向之后, 其对降水的负面影响要弱得多.