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雷暴电荷分布对正极性云闪放电特征影响的数值模拟
引用本文:郑天雪,谭涌波,罗林洁.雷暴电荷分布对正极性云闪放电特征影响的数值模拟[J].大气科学,2022,46(6):1407-1424.
作者姓名:郑天雪  谭涌波  罗林洁
作者单位:1.南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心/中国气象局气溶胶与云降水重点开放实验室, 南京 210044
基金项目:国家重点研发计划项目2017YFC1501504,国家自然科学基金项目41875003,灾害天气国家重点实验室开放课题2019LASW-A03
摘    要:本研究将云闪随机放电参数化方案植入到偶极电荷结构中,固定主负电荷区的参数和位置,通过不断调整上部正电荷区的参数(电荷浓度和水平范围)和位置以此来模拟不同高度处起始的正极性云闪,进而探讨正云闪放电特征与雷暴电荷分布之间的关系。模拟结果表明在偶极电荷结构中,抬升上部正电荷区的高度,能够产生如观测所示的高海拔正云闪,不同于普通正云闪起始于向上传播的负先导及水平或稍向下延伸的正先导,高海拔处起始的正云闪以大范围向下传播的正先导及水平或轻微向上延伸的负先导为主要特征。随着上部正电荷区位置的抬升,正云闪起始高度也随之升高,当上部正电荷区抬升到一定高度后(本研究中当上部正电荷区下边界超过12 km),云闪通常起始于主正电荷区内,且上部正电荷区的浓度以及水平半径对于云闪的起始高度没有显著影响。此外,云闪正、负先导通道的长度与电荷区的浓度、水平半径以及起始点和负、正电荷区之间的距离存在显著的正相关关系。

关 键 词:正极性云闪    数值模拟    雷暴电荷分布    起始高度    通道长度
收稿时间:2021-05-08

Numerical Simulation of the Effects of Thunderstorm Charge Distributions on the Discharge Characteristics of Positive Intracloud Lightning Flashes
Abstract:In this study, a stochastic lightning parameterization scheme is coupled with a dipole charge structure, and the parameters and positions of the main negative charge region are fixed. Positive intracloud (+IC) flashes initiating at different altitudes are simulated by adjusting the parameters (charge concentration and horizontal range) of the upper positive charge region, and then the relationships between the characteristics of the +IC flashes and thunderstorm charge distributions are discussed. Simulation results indicate that in dipole charge structures, the elevation of the upper positive charge region can generate high-altitude +IC flashes, which is consistent with observations. Unlike normal IC flashes that are dominated by upward negative leaders and horizontal or slightly downward positive leaders, IC flashes initiated at high altitudes are characterized by long-distance downward positive leaders and horizontal or slightly upward negative leaders. The initiation altitudes of +IC flashes increase with the elevation of the upper positive charge region. When the upper positive charge region is lifted to a certain altitude (in this paper, the upper positive charge region’s lower boundary altitude is 12 km), IC flashes are usually initiated from the main positive charge region, and the concentration and horizontal radius of the upper positive charge region have no major effect on the initiation altitude of IC flashes. In addition, the length of positive or negative leader channels has a substantial positive correlation with concentration and horizontal radius of the charge region and the distance between the initiation point and the negative or positive charge region.
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