| 大气冰核对雷暴云电过程影响的数值模拟 |
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| 引用本文： | 师正,管啸林,林晓彤,谭涌波,郭秀峰,汪海潮.大气冰核对雷暴云电过程影响的数值模拟[J].大气科学,2023,47(1):20-33. |
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| 作者姓名： | 师正 管啸林 林晓彤 谭涌波 郭秀峰 汪海潮 |
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| 作者单位： | 1.南京信息工程大学大气物理学院/中国气象局气溶胶与云降水重点开放实验室, 南京 210044 |
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| 基金项目： | 国家自然科学基金项目41805002、42205078，灾害天气国家重点实验室开放课题2021LAW-B05，南京信息工程大学人才启动项目2016r042 |
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| 摘 要： | 利用已有的二维雷暴云起、放电模式模拟了一次雷暴天气，并通过敏感性试验研究了冰核浓度变化对雷暴云动力、微物理及电过程的影响。结果表明：随着大气冰核浓度的增加，雷暴云发展提前，上升气流速度和下沉气流速度均呈现降低的趋势。大气冰核浓度提升有利于异质核化过程增强，冰晶在高温区大量生成，而同质核化过程被抑制，因此冰晶整体含量降低，引起低温区中霰粒含量降低和高温区中霰粒尺度降低。在非感应起电过程中，正极性非感应起电率逐渐减小，负极性非感应起电率逐渐增大。由于液态水含量随大气冰核浓度的增加逐渐降低，高温度冰晶携带电荷的极性由负转变为正的时间有所提前。在感应起电过程中，由于霰粒尺度减小及云滴的快速消耗，感应起电率极值逐渐降低。冰晶优先在高温区生成而带负电，不同大气冰核浓度下的雷暴云空间电荷结构在雷暴云发展初期均呈现负的偶极性电荷结构。在雷暴云旺盛期，随着冰核浓度增加，空间电荷结构由三极性转变为复杂四极性。在雷暴云消散阶段不同个例均呈现偶极性电荷结构，且随着冰核浓度的增加电荷密度值逐渐减小。
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| 关 键 词： | 大气冰核 起电率 电荷结构 数值模拟 |
| 收稿时间： | 2021-06-17 |
Numerical Simulation on the Effect of Ice Nuclei on the Electrification Process of Thunderstorms |
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| Affiliation: | 1.School of Atmospheric Physics/China Meteorological Administration Aerosol–Cloud–Precipitation Key Laboratory, Nanjing University of Information Science & Technology, Nanjing 2100442.State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 1000813.College of Atmospheric and Remote Sensing, Wuxi University, Wuxi 214105 |
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| Abstract: | This work is conducted based on an existing two-dimensional convective cloud model to investigate the role of ice nuclei in dynamic, microphysical, electrification, and charge structure in thunderstorm clouds by changing the concentration of ice nuclei. The results show that thunderstorm clouds develop ahead of time as ice nuclei increase and both updraft and downdraft velocities decrease. A high concentration of ice nuclei enhances the heterogeneous nucleation process. In the high-temperature region, a large number of ice crystals form while the homogeneous nucleation process is inhibited. Therefore, the overall content of ice crystals decreases, resulting in a decrease in graupel content in the low-temperature region and a decrease in graupel size in the high-temperature region. Therefore, the positive non-inductive electrification rate decreases while the negative non-inductive electrification rate increases. The time for the polarity of charge carried by high-temperature ice crystals to change from negative to positive is advanced as the liquid water content gradually decreases with increasing ice nuclei concentration. The extreme value of the inductive electrification rate gradually decreases during the process of inductive electrification due to the decrease in graupel particle size and the rapid consumption of cloud droplets. Because the ice crystals are preferentially generated in the high-temperature region and are negatively charged, the space charge structure of thunderstorm clouds with different ice nuclei concentrations presents a negative dipole charge structure at the initial stage of thunderstorm cloud development. With an increase in ice nuclei concentration, the space charge structure changes from three polarities to a complex four-order structure during the thunderstorm’s growing period. In the dissipation stage of a thunderstorm cloud, different cases show dipole charge structures, and the charge density decreases with the increased concentration of ice nuclei. |
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