| 北京北部山区两次降雪过程微物理形成机制的观测—模拟研究 |
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| 引用本文： | 高茜,郭学良,刘香娥,何晖.北京北部山区两次降雪过程微物理形成机制的观测—模拟研究[J].大气科学,2020,44(2):407-420. |
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| 作者姓名： | 高茜 郭学良 刘香娥 何晖 |
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| 作者单位： | 1.中国科学院大气物理研究所, 北京 100029;北京市人工影响天气办公室, 北京 100089;中国气象局北京城市气象研究所, 北京 100089;中国科学院大学, 北京 100049;云降水物理研究与云水资源开发北京市重点实验室, 北京 100089 |
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| 基金项目： | 国家自然科学基金项目41805114、41675138、41775138，北京市自然科学基金项目8164058、8182024、8172023 |
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| 摘 要： | 降雪是北京冬季的重要降水天气过程,但目前对实例降雪形成的微物理机制的观测-模拟研究较少。本文利用中尺度WRF模式结合外场观测资料,对北京2015年1月24日和11月5~6日两次不同天气条件下的山区降雪云系的微物理结构特征及降雪形成的微物理转化机制进行了分析研究,定量比较了云中水凝物含量的比例和降雪形成机制的差异。研究结果表明:(1)由于两次降雪过程的天气形势和水汽输送有较大差异,导致降雪形成的微物理转化机制也出现较大差异。11月5日降雪第一阶段水汽输送较强,云中过冷水含量较高,降雪形成以凝华增长和凇附增长为主,地面表现为雨夹雪天气,而1月24日和11月5~6日第二阶段水汽输送弱,降雪形成以凝华增长和聚并增长为主,地面表现为纯降雪天气;(2)11月5日的雨夹雪天气过程中,云中不仅有冰晶(9%)、雪晶(72%),还有云水(6%)和雨水(12%)的存在,高层生成的雪胚在下落过程中主要通过凝华(78%)和凇附(20%)过程增长。而1月24日与11月5~6日第二阶段的纯降雪过程中,云中水凝物分布相似,以冰晶和雪晶为主,1月24日冰晶含量占28%,雪晶含量占72%;11月5~6日冰晶含量占11%,雪晶含量占88%,冰粒子主要分布在高层。首先高层6~12 km通过云冰转换生成的雪胚下落到低层水汽充足区,然后通过凝华和聚并过程增长,1月24日凝华增长过程占92%,聚并增长过程仅占5%;11月5~6日凝华占88%,聚并仅占3%。(3)垂直上升气流速度与冰晶、雪晶生成和增长过程呈正相关,上升气流带来充足的水汽,配合垂直运动使得雪胚增加,凝华、凇附凇附和聚并过程增强,导致雪晶含量增加。
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| 关 键 词： | 北京山区 冬季降雪 微物理特征 |
| 收稿时间： | 2018/6/8 0:00:00 |
Numerical Simulation and Observation Study on Microphysical Formation Processes of Two Different Snowfall Cases in Northern Mountain Area of Beijing |
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| GAQ Qian,GUO Xueliang,LIU Xiang''e and HE Hui.Numerical Simulation and Observation Study on Microphysical Formation Processes of Two Different Snowfall Cases in Northern Mountain Area of Beijing[J].Chinese Journal of Atmospheric Sciences,2020,44(2):407-420. |
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| Authors: | GAQ Qian GUO Xueliang LIU Xiang'e and HE Hui |
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| Institution: | Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;Beijing Weather Modification Office, Beijing 100089;Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089;University of Chinese Academy of Sciences, Beijing 100049;Key Laboratory of Beijing for Cloud, Precipitation and Atmospheric Water Resources, Beijing 100089,Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029,Beijing Weather Modification Office, Beijing 100089;Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089;Key Laboratory of Beijing for Cloud, Precipitation and Atmospheric Water Resources, Beijing 100089 and Beijing Weather Modification Office, Beijing 100089;Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089;Key Laboratory of Beijing for Cloud, Precipitation and Atmospheric Water Resources, Beijing 100089 |
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| Abstract: | Snowfall is an important precipitation system in Beijing. In this study, observation data in combination with the WRF mesoscale numerical simulation model were used to analyze the microphysical processes of two different snowfall cases in the northern mountain area of Beijing. The results showed the following: (1) Because of the great differences in weather situation and water vapor transport during these two snowfall processes, great differences existed in the microphysical mechanism of these two snowfall cases. In period I of November 5, 2015, due to a strong water vapor transport, there was more liquid water in the cloud, and deposition and rimming processes were the main formation processes for snow particles. However, deposition and coalescence were the main formation processes for snowfall cases on January 24 and in period II of November 5-6 for the weak water vapor transport. (2) In period I of November 5, the air contained ice crystal (9%), snow crystal (72%), cloud liquid water (6%), and rainwater (12%), and the snow particles grew with deposition (78%) and rimming (20%) processes. On January 24, the air contained ice crystal (28%) and snow crystal (72%); meanwhile, period II of November 5-6 had a similar portion: ice crystal (11%) and snow crystal (88%). Moreover, snow particles grew through deposition and coalescence on January 24 and in period II of November 5-6. (3) Updraft has a great influence on the ice crystal and snow crystal growth processes because it results in sufficient water vapor. The vertical motion and water vapor make more snow for strong deposition, rimming, and coalescence processes. |
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| Keywords: | Northern mountain area of Beijing Snowfall Microphysical process |
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