拉萨夏季大气边界层气溶胶垂直结构特征  

Vertical Structural Characteristics of Aerosols in the Atmospheric Boundary Layer during the Summer in Lhasa

作　　者：李若羽 卞建春[2,3,4] 唐贵谦 李丹 白志宣 毛文书 LI Ruoyu;BIAN Jianchun;TANG Guiqian;LI Dan;BAI Zhixuan;MAO Wenshu(Chengdu University of Information Technology,Chengdu 610225;Key Laboratory of Middle Atmosphere and Global Environmental Sounding,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029;School of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049;School of Atmospheric Sciences,Lanzhou University,Lanzhou 730000;State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry(LAPC),Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029)

机构地区：[1]成都信息工程大学大气科学学院,成都610225 [2]中国科学院大气物理研究所中层大气和全球环境探测重点实验室,北京100029 [3]中国科学院大学地球与行星科学学院,北京100049 [4]兰州大学大气科学学院,兰州730000 [5]中国科学院大气物理研究大气边界层物理和大气化学国家重点实验室(LAPC),北京100029

出　　处：《大气科学》2022年第3期666-676,共11页Chinese Journal of Atmospheric Sciences

基　　金：第二次青藏高原综合科学考察研究项目2019QZKK0604;国家自然科学基金项目41905041。

摘　　要：大气污染物的垂直梯度观测是识别区域输送和本地贡献的必要手段。基于此,2020年8月在拉萨市利用光学粒子计数器(the Printed Optical Particle Spectrometer,简称POPS)在地面和系留气艇分别对0.13~3.39μm粒径范围的气溶胶数浓度进行了测定。结果表明:(1)拉萨近地面气溶胶数浓度在16 cm^(−3)到870 cm^(−3)范围之间,比华北和珠江三角洲地区小2~3个量级;(2)气溶胶数浓度呈现两峰两谷的日变化结构,峰值通常以0.13~0.4μm的小粒径粒子为主,且对应北京时间早(10:00)、晚(21:00)高峰时段;(3)气溶胶数浓度垂直分布与边界层演变密切相关,稳定边界层中的气溶胶随高度递减,粒子数浓度为194±94 cm^(−3),对流边界层和残留层中的气溶胶分布均一,数浓度分别为165±99 cm^(−3)和123±95 cm^(−3),且显著低于稳定边界层。以上研究结果表明,拉萨的污染源主要为局地机动车排放,机动车污染物减排是打造高原生态旅游城市的必由之路。To determine regional transport and local contribution,vertical gradient observation of air pollutants is required.Based on this,the number concentrations of aerosols in the particle size range of 0.13–3.39μm were recorded with an optical particle counter POPS(the Printed Optical Particle Spectrometer)at ground level and in a tethered airboat in Lhasa in August 2020.The results demonstrate that(1)near-ground aerosol number concentrations in Lhasa range from 16 cm^(−3) to 870 cm^(−3),which is 2–3 orders of magnitude lower than those in northern China and the Yangtze River Delta.(2)The daily variation structure of the aerosol number concentration display two peaks and valleys.The peaks,which correlate to morning and evening peaks[1000 BJT(Beijing time)and 2100 LT,respectively],are usually dominated by small particles of 0.13–0.4μm.(3)Furthermore,the vertical distribution of the aerosol number concentration is closely related to the evolution of the boundary layer.The aerosol in the stable boundary layer decreases with height,and the particle number concentration is 194±94 cm^(−3).Conversely,the aerosols in the convective boundary and residual layers are uniformly distributed with the number concentrations of 165±99 cm^(−3) and 123±95 cm^(−3),respectively,which are significantly lower than that in the stable boundary layer.According to the above research results,local motor vehicle emissions are the main sources of pollution in Lhasa.Therefore,motor vehicles must be controlled and emissions must be reduced to build a highland ecotourism city.

关 键 词：边界层结构 气溶胶 垂直廓线 拉萨 数浓度 

分 类 号：P404[天文地球—大气科学及气象学]