前次云闪对上行闪电始发提供的有利电环境特征分析

Assessment of Favorable Electric Environment Characteristics Provided by Preceding Intracloud Flash to Upward Lightning

主要基于已有的二维雷暴云起、放电模式背景下的上行闪电随机放电参数化方案,来进行二维高分辨率闪电放电的模拟实验,定量探讨了云闪放电过程对上行闪电的触发产生的有利作用。研究结果表明:云闪触发型上行闪电均发生于典型三极电荷结构下,当前次云闪结束后,在上部主正与中部主负电荷区内植入了大量异极性电荷,而底部次正电荷区几乎未受影响。近地面(0-3 km)的空间电位在云闪结束后由负位势转为正位势,负位势阱中心上移甚至消失,地面出现正位势阱中心;云闪放电后,空中原有强电场被摧毁,空间整体电场降低,与此同时,上部主正、主负电荷区对地面电场的作用明显削弱,而由于底部次正电荷区保持相对完整,其对地面电场的作用显著增强,电场极性发生反转、电场值增强,促使上行闪电始发。

The auttor is mainly based on a stochastic parameterization scheme for the upward lightningunder the background of an existing two-dimensional thundercloud charge/discharge model.Through multiple groups of experimentswith two-dimensional high resolution,quantitative analyzing the beneficial effect of the intracloud lightning to trigger generated upward lightning.The results show that the intracloud-lightning-triggered upward flashes occur in the typical three pole charge structure.A large number of hetero polar charges are implanted in the main positive and negative charge regions afterpreceding intracloud flashes(IC),while the bottom secondary positive charge area is almost unaffected.After the intracloud flash,the negative potential near ground space(0-3 km)turn to positive potential and negative potential wellmoved up;At the same time,the original strong electric field is destroyed,the whole space electric field is reduced,the main positive and negative charge region's affection to the ground electric field is obvious weakened.Because of the positive charge region remained relatively intact,the ground electric field significantly enhanced electric field polarity reversed,the values of electric field enhancement,the upward lightning triggered.