Evaluation of noninductive charging mechanisms and simulation of charge characteristic structure in the early thunderstorm based on RAMS V6.0
基于RAMS V6.0的非感应起电机制评估和雷暴初期电荷结构模拟

A new regional thunderstorm model, coupled with two primary non-inductive electrification mechanisms, namely Takahashi (1978) and Saunders (1991) schemes, is developed based on the newest version of RAMS V6.0. Based on the simulation on a thunderstorm in its early stage which occurred in Beijing, the results show that the total charge distribution is tripolar in both schemes when the electric field reaches breakdown value. The results are in agreement with some observations and results of other model. However, the evolution processes and shapes of cloud charge distribution in the two schemes are different. The result of Takahashi's (1978) scheme produces a tripolar charge distribution in the cloud before the first lightning. The Saunders' (1991) scheme produces a transform from inverted dipole distribution to tripolar charge distribution. This is because they used different experimental conditions: different factors lead to different results. The results from both schemes show that the positive charge carrier at a low level of thunderstorm is rain droplet, the aggregates and graupels are located in high level of thunderstorm, and the charge center distribution of graupels is similar to the distribution of total charge in thunderstorm cloud.