北京大学学报自然科学版 ›› 2021, Vol. 57 ›› Issue (6): 1019-1026.DOI: 10.13209/j.0479-8023.2021.082

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PM2.5浓度湍流特征和通量获取的实验研究

任燕1,2, 李倩惠1, 张宏升1,†, 康凌3   

  1. 1. 北京大学物理学院大气与海洋科学系, 气候与海?气实验室, 北京100871 2. 兰州大学西部生态安全省部共建协同创新中心, 兰州 730000 3. 环境模拟与污染控制国家重点联合实验室, 北京大学环境科学与工程学院, 北京100871
  • 收稿日期:2020-11-22 修回日期:2021-01-20 出版日期:2021-11-20 发布日期:2021-11-20
  • 通讯作者: 张宏升, E-mail: hsdq(at)pku.edu.cn
  • 基金资助:
    国家重点研发计划(2017YFC0209904, 2017YFC0209600)、国家自然科学基金(41705003, 41544216)和新疆维吾尔自治区高层次(柔性)人才引进项目(2018)资助

Experimental Study on the Turbulence Characteristics and Flux Acquisition of PM2.5

REN Yan1,2, LI Qianhui1, ZHANG Hongsheng1,†, KANG Ling3   

  1. 1. Laboratory for Climate and Oceanic-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871 2. Collaborative Innovation Center for West Ecological Safety, Lanzhou University, Lanzhou 730000 3. State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871
  • Received:2020-11-22 Revised:2021-01-20 Online:2021-11-20 Published:2021-11-20
  • Contact: ZHANG Hongsheng, E-mail: hsdq(at)pku.edu.cn

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摘要：

利用PM2.5质量浓度测量仪E-Sampler的1 Hz高频采样功能, 采用涡动相关法, 计算山东省德州大气环境实验站2018年12月27日至2019年1月7日多次污染事件的PM2.5浓度脉动和湍流通量, 探讨PM2.5浓度湍流特征。结果表明, 实验观测期间PM2.5浓度湍流通量均值为0.026 μg/(m2·s); 不同污染过程中PM2.5浓度湍流通量传输方向不同, 表明不同污染过程的污染源汇属性不同。随着湍流统计特征量(如湍流动能、水平风速标准差、垂直风速标准差、水平风速、动量通量和感热通量)增大, PM2.5湍流垂直通量呈现指数型减小的趋势, 即先急剧减小, 然后随各变量的增长变化不大。随着PM2.5浓度增大, 其湍流通量绝对值呈现增加趋势, 因此PM2.5浓度湍流通量的大小与PM2.5浓度和湍流强弱有关。不稳定条件下, PM2.5浓度归一化标准差与稳定度参数ζ = z/L 遵循-1/3幂次关系, 即 σc/C* = 6.7(-ζ)-1/3; 稳定条件下, 实验结果相对离散。另外, PM2.5浓度脉动方差谱曲线在高频段满足-2/3幂指数率, PM2.5浓度脉动与垂直速度脉动的协方差谱曲线在高频段满足-4/3幂指数率。研究结果表明, 利用E-Sampler的PM2.5浓度1 Hz高频采样功能可以得到连续且有效的PM2.5浓度湍流通量。

关键词: PM2.5浓度湍流通量, 湍流统计特征, 湍流能谱, 污染过程

Abstract:

The authors use the high-frequency sampling function of the fine particle mass concentration measurement instrument E-Sampler and the eddy covariance method to calculate PM2.5 concentration fluctuation and turbulent flux of the multiple pollution events of the Dezhou city atmospheric environment experimental station in Shandong Province from December 27, 2018 to January 7, 2019, and the turbulence characteristics of PM2.5 concentration are discussed. The results show that the mean value of the turbulent flux of PM2.5 concentration during the observation period is 0.026 μg/(m2·s). The transmission direction of the turbulent flux of PM2.5 concentration in different pollution processes is different, indicating that the sink or source property is not static. With the increase of turbulence statistical characteristic quantities (such as turbulent kinetic energy, standard deviation of horizontal wind speed, standard deviation of vertical wind speed, horizontal wind speed, momentum flux and sensible heat flux), the vertical flux of PM2.5 decreases exponentially, namely, it decreases sharply, and then changes little with the increase of each variable. With the increase of the concentration of PM2.5, the absolute value of the turbulent flux of PM2.5 shows an increasing trend. The turbulent vertical flux of PM2.5 concentration is related to the PM2.5 concentration and the intensity of turbulence. The normalized standard deviation of PM2.5 concentration and the stability parameter ζ = z/L follow the -1/3 power relationship under unstable conditions, that is σc/C* = 6.7(-ζ)-1/3. Under stable conditions, the experimental results are relatively discrete. In addition, the variance spectrum curve of PM2.5 concentration satisfies the -2/3 power exponential rate in the high frequency range, and the covariance spectrum curve of the PM2.5 concentration and the vertical wind speed satisfies the ?4/3 power exponential rate in the high frequency band. The result shows that 1 Hz high-frequency sampling function of E-Sampler can obtain continuous and effective turbulent flux of PM2.5 concentration.

Key words: turbulent flux of PM2.5concentration, turbulence statistics, turbulence energy spectrum, pollution process

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