灰霾等高浓度气溶胶中主要污染物粒子散射特性的研究
发布时间：2019-06-27 14:40
【摘要】：随着经济规模不断扩大,城市化节奏越来越快,汽车数量大规模增加,人类生产活动造成细粒子气溶胶污染现象不断加重,灰霾天气日益增加,在国内存在四个灰霾现象较为严重的地域:京津唐地区、四川盆地、珠三角以及长江三角洲地域,表现出产生频率逐渐增加、成霾面积不断扩大的特征。像北上广等地,全年不止1/3天数都是灰霾天气,更有甚者超过一半。而面对细粒子本身体积小、质量轻、较难沉降和滤除的特点,沙尘、灰霾等大气浑浊现象很难得到有效控制。因此,人类的生存生活和地球气候环境严重受到影响,为此对灰霾、沙尘等高浓度气溶胶的研究成为目前讨论的热点,引起了科学界高度重视。本文主要从以下几个方面讨论了灰霾等高浓度气溶胶条件下的有关散射传输问题的研究进展;(1)大气气溶胶粒子的物理光学特性;(2)粒子吸湿变化对粒子散射传输的影响;(3)气溶胶偏振反射特性;(4)地气间多次散射问题,高浓度气溶胶条背景下矢量辐射传输建模的研究。同时,由于大气气溶胶对光线有散射和吸收作用,其消光效应直接影响大气的能见度,相关的散射理论有:瑞利散射,米散射,以及非球形粒子的T矩阵方法和DDA理论等等。灰霾发生时微粒(D2.5μm)中水溶性离子NH4+、NO3-和SO42-的浓度远大于正常天气,它们是PM2.5的主要化学成分,主要以铵盐的形式存在。这些高浓度的铵盐有利于生成二次颗粒物,造成能见度低下,促使灰霾形成,因此,灰霾期间颗粒物较非灰霾日偏酸性,除此之外,元素碳和有机碳也会促成灰霾的形成。而PM2.5化学成分受地域和污染源的影响会产生很大差异,目前含量较多的成分是硫酸铵,硫酸,硝酸铵和碳质气溶胶粒子等。因此,本文主要以上述气溶胶粒子为研究对象,分别以Mie理论和T矩阵方法研究了对应组分的单个球形粒子和非球形粒子的散射特性,非球形微粒形状主要包括椭球形(长短轴比为1/2,1/3,2/1),圆柱形(直径与长度比为1/2,1/3,2/1)和切比雪夫形(其多项式n=2,形变参数为-0.1和0.1)三种。重点分析了对应粒子的消光、散射和吸收效率因子随尺度参数的变化,以及散射相函数随散射角的变化特性。研究表明,硫酸铵、硫酸和硝酸铵粒子主要以散射作用为主,而碳质气溶胶则呈现很强的吸收效应,而且非球形微粒的各效率因子和球形的差异变化呈现先增后减,最后又增大的规律。最后通过对比不同半径不同粒子的散射相函数,表明散射相函数对粒子大小和复折射率极其敏感。该研究结果可用于大气环境污染的光学遥感监测。
[Abstract]:With the continuous expansion of economic scale, the pace of urbanization and the large-scale increase of the number of cars, the phenomenon of fine particle aerosol pollution caused by human production activities is increasing, and the haze weather is increasing day by day. There are four serious haze areas in China: Beijing-Tianjin-Tang region, Sichuan Basin, Pearl River Delta and Yangtze River Delta, showing the characteristics of increasing frequency and increasing haze area. In places such as Beishangguang, more than 1 / 3 days of the year are haze, and more than half of them are haze. In the face of the characteristics of small size, light mass, difficult to settle and filter, it is difficult to effectively control the atmospheric turbidity such as sand, haze and so on. Therefore, the survival and life of human beings and the climate and environment of the earth are seriously affected. Therefore, the study of haze, dust and other high concentration aerosols has become the focus of discussion at present, which has attracted great attention of the scientific community. In this paper, the research progress of scattering transport under the condition of haze and other high concentration aerosols is discussed from the following aspects: (1) the physical and optical properties of atmospheric aerosol particles; (2) the influence of particle moisture absorption on particle scattering transmission; (3) the polarized reflection characteristics of aerosols; and (4) the modeling of vector radiation transport under the background of multiple scattering between ground gases and high concentration aerosol strips. At the same time, due to the scattering and absorption of light by atmospheric aerosols, the extinction effect directly affects the visibility of the atmosphere. The related scattering theories are: Rayleigh scattering, meter scattering, T matrix method and DDA theory of non-spherical particles, and so on. When haze occurs, the concentrations of water-soluble ions NH4, NO3- and SO42- in particles (D2.5 渭 m) are much higher than those in normal weather. They are the main chemical components of PM2.5, mainly in the form of ammonium salt. These high concentrations of ammonium salt are beneficial to the formation of secondary particles, resulting in poor visibility and the formation of haze. Therefore, the particles are more acidic than non-haze during haze. In addition, elemental carbon and organic carbon also contribute to the formation of haze. However, the chemical composition of PM2.5 is very different by the influence of region and pollution sources. At present, ammonium sulfate, sulfuric acid, ammonium nitrate and carbonaceous aerosol particles are the most important components. Therefore, in this paper, the scattering characteristics of single spherical particles and non-spherical particles corresponding to the corresponding components are studied by Mie theory and T matrix method, respectively. the shape of non-spherical particles mainly includes ellipsoid shape (the ratio of length to short axis is 1: 2, 1: 3, 2: 1), cylinder (diameter to length ratio is 1: 2, 1: 3, 2: 1) and Chebyshev shape (its multinomial n 鈮，
本文编号：2506881
[Abstract]:With the continuous expansion of economic scale, the pace of urbanization and the large-scale increase of the number of cars, the phenomenon of fine particle aerosol pollution caused by human production activities is increasing, and the haze weather is increasing day by day. There are four serious haze areas in China: Beijing-Tianjin-Tang region, Sichuan Basin, Pearl River Delta and Yangtze River Delta, showing the characteristics of increasing frequency and increasing haze area. In places such as Beishangguang, more than 1 / 3 days of the year are haze, and more than half of them are haze. In the face of the characteristics of small size, light mass, difficult to settle and filter, it is difficult to effectively control the atmospheric turbidity such as sand, haze and so on. Therefore, the survival and life of human beings and the climate and environment of the earth are seriously affected. Therefore, the study of haze, dust and other high concentration aerosols has become the focus of discussion at present, which has attracted great attention of the scientific community. In this paper, the research progress of scattering transport under the condition of haze and other high concentration aerosols is discussed from the following aspects: (1) the physical and optical properties of atmospheric aerosol particles; (2) the influence of particle moisture absorption on particle scattering transmission; (3) the polarized reflection characteristics of aerosols; and (4) the modeling of vector radiation transport under the background of multiple scattering between ground gases and high concentration aerosol strips. At the same time, due to the scattering and absorption of light by atmospheric aerosols, the extinction effect directly affects the visibility of the atmosphere. The related scattering theories are: Rayleigh scattering, meter scattering, T matrix method and DDA theory of non-spherical particles, and so on. When haze occurs, the concentrations of water-soluble ions NH4, NO3- and SO42- in particles (D2.5 渭 m) are much higher than those in normal weather. They are the main chemical components of PM2.5, mainly in the form of ammonium salt. These high concentrations of ammonium salt are beneficial to the formation of secondary particles, resulting in poor visibility and the formation of haze. Therefore, the particles are more acidic than non-haze during haze. In addition, elemental carbon and organic carbon also contribute to the formation of haze. However, the chemical composition of PM2.5 is very different by the influence of region and pollution sources. At present, ammonium sulfate, sulfuric acid, ammonium nitrate and carbonaceous aerosol particles are the most important components. Therefore, in this paper, the scattering characteristics of single spherical particles and non-spherical particles corresponding to the corresponding components are studied by Mie theory and T matrix method, respectively. the shape of non-spherical particles mainly includes ellipsoid shape (the ratio of length to short axis is 1: 2, 1: 3, 2: 1), cylinder (diameter to length ratio is 1: 2, 1: 3, 2: 1) and Chebyshev shape (its multinomial n 鈮，
本文编号：2506881
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