中文关键词无人机探空重污染天气数值模拟标记法过程分析 英文关键词unmanned aerial vehicle soundingheavy pollution episodenumerical modelmarking methodprocess analysis

作者	单位	E-mail
杨旭	天津市环境气象中心, 天津 300074 中国气象局-南开大学大气环境与健康研究联合实验室, 天津 300074	yangx_tjqx@163.com
蔡子颖	天津市环境气象中心, 天津 300074 中国气象局-南开大学大气环境与健康研究联合实验室, 天津 300074	120078030@163.com
韩素芹	天津市环境气象中心, 天津 300074 中国气象局-南开大学大气环境与健康研究联合实验室, 天津 300074
史静	天津市气象探测中心, 天津 300074
唐颖潇	天津市环境气象中心, 天津 300074 中国气象局-南开大学大气环境与健康研究联合实验室, 天津 300074
姜明	天津市气象探测中心, 天津 300074
邱晓滨	天津市气象科学研究所, 天津 300074

中文摘要 污染发生在边界层中，边界层热力和动力垂直结构对重污染天气形成有显著影响.本文基于无人机探空、地基遥感观测和数值模式，开展天津地区2019年1月10~15日重污染过程期间边界层垂直结构及污染成因分析，以期加强北方沿海城市边界层过程对重污染影响规律认知，提升重污染天气预报预警准确率.结果表明：大气温度层结对重污染天气形成、持续和消散有显著影响，此次过程伴随逆温层的发展和消散，PM_2.5高浓度区白天向大气上层发展，高度可达300 m以上，夜间向近地面压缩，高度在100 m左右；雾天气出现并在白天维持，改变了边界层垂直结构特征，雾顶逆温的持续存在抑制了污染物向大气上层扩散，使得白天湍流垂直混合过程贡献明显下降，导致近地面重污染天气维持和发展；过程期间区域输送贡献率为66.6%，边界层垂直结构与重污染天气区域输送密切相关，区域污染物输送高度主要出现在边界层顶部以及雾顶逆温层以上的大风速层处，且随着边界层和雾顶抬升高度的变化，通过下沉运动影响地面，形成北部弱高压天气控制下静稳天气区域输送；边界层垂直结构影响冷空气对空气质量的改善效果，S3阶段雾顶的强逆温导致冷空气无法通过湍流切应力传导到地面，在高低空存在明显的风速差，冷空气影响地面时间延后，作用减弱，重污染天气无法彻底缓解. 英文摘要 Pollution occurs in the boundary layer, and the thermal and dynamic vertical structure of the boundary layer has a significant influence on the formation of heavy pollution episodes. Based on unmanned aerial vehicle (UAV) sounding, ground-based remote sensing and numerical modeling, this paper analyzes the vertical structure of the boundary layer and the causes of pollution during the heavy pollution episode in Tianjin from January 10 to 15, 2019, with a view to strengthening the understanding of the influence law of boundary layer processes on heavy pollution in northern coastal cities and improving the accuracy of weather forecasts and heavy pollution warnings. The results show that atmospheric temperature stratification had a significant influence on the formation, persistence, and dissipation of heavy pollution episodes. During an episode, accompanied by the development and dissipation of the inversion layer, a high PM_2.5 concentration area developed to the upper atmosphere with a height of over 300 m in the daytime and compressed to the ground at night with a height about 100 m. When fog appeared and continued in the daytime, the vertical structure characteristics of the boundary layer changed. A temperature inversion above the fog restrained the diffusion of pollutants to the upper air and made the contribution of turbulence vertical mixing process decrease significantly in the daytime, leading to the persistence and development of heavy pollution near the surface. Regional pollution transport accounted for 66.6% during the episode, which was closely related to regional pollution transport. Regional pollution transport mainly appeared at the top of the boundary layer and above the fog inversion layer where high wind speeds occurred. Pollutants were transported to the ground by a sinking motion as the boundary layer and fog height changed. This is how regional pollution transport occurred when Tianjin was controlled by a weak high pressure field in the north. The vertical structure of the boundary layer also affected the improvement of air quality by cold air. The strong temperature inversion at the top of the fog resulted in the failure of the cold air to transmit to the ground through turbulent shear stress in the S3 stage. There was an obvious difference in wind speed between the upper and lower air. The influence of cold air on the ground was delayed, and the effect of it was weakened. Thus, the heavy pollution episode could not be alleviated completely.

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