基于卫星和AERONET观测的北京地区气溶胶光学特性研究

发布时间：2019-06-13 21:07

【摘要】：随着经济的发展和城市化进程的加快,北京及其周边环渤海地区的大气污染问题日益严重,对人类的生活环境产生严重的影响。因此,对北京地区进行长期有效的气溶胶观测研究,并了解大气污染环境下气溶胶的光学特性,对改善空气质量、评估区域大至全球的气溶胶辐射强迫和了解气候变化都是至关重要的。本文主要结合MODIS数据、CALIPSO数据和AERONET观测网数据,采用交互式数据语言IDL(Interactive Data Language)处理数据的方法研究北京地区气溶胶的光学特性。首先以2013年3月的典型沙尘天气作为个例进行分析,采用CALIPSO和MODIS数据,根据532nm波长的衰减后向散射系数β’532(Z)和双波长信号比χ’的SCA法对气溶胶和云进行区分;然后采用CLIM方法来进一步识别沙尘气溶胶,给出了沙尘识别的结果;再利用HYSPLIT模式和NAAPS气溶胶模式进行沙尘来源和传输过程模拟分析,并用双波长反演法初步反演了气溶胶的光学厚度值。然后利用AERONET的太阳直接辐射资料反演沙尘气溶胶的光学特性,统计分析北京地区2001~2013年期间沙尘天气情况下沙尘气溶胶的光学特性。最后利用AERONET的太阳直接辐射资料反演北京地区气溶胶的光学厚度,以及采用天空散射辐射资料反演气溶胶的单次散射反照率、复折射指数以及体积谱分布等光学特性参数,统计分析北京地区2002~2013年气溶胶光学特性的季节性变化。研究结果如下:(1)从各光学特性参数的空间分布图可以得出气溶胶和云的空间分布情况及其分布高度;结合采用SCA和CLIM方法可以较好的区分气溶胶和云以及识别沙尘气溶胶。(2)以2013年3月9~11日典型沙尘天气作为个例分析的结果表明:北京地区沙尘天气情况下,沙尘气溶胶的退偏振比在0.1~0.4之间,色比通常大于0.3,且沙尘的分布高度一般在4km以下。通过采用HYSPLIT模式和NAAPS气溶胶模式模拟分析发现此次沙尘起源于南疆盆地和内蒙古中西部地区,符合我国沙尘天气传输路径中的偏西路径型。在沙尘传输过程中,沙尘天气对北京的空气质量影响显著,主要污染物从PM2.5转换为PM10。本文采用双波长迭代反演法初步反演了此次沙尘暴对北京地区造成的沙尘天气情况下沙尘气溶胶的光学厚度,分别为0.534和0.621。(3)2001年~2013年的北京沙尘天气分析结果:北京沙尘天气期间受沙尘粒子的影响,气溶胶光学厚度值较大,随波长的增大而减小,在波长440nm处最大,平均值约为1.2;气溶胶Angstrom波长指数97.62%均聚集在0.7以下,说明北京沙尘天气期间粒子较大;沙尘天气期间单次散射反照率随波长增加而增加,平均值约为0.93;复折射指数实部在波长675nm处最大,平均约为1.55,虚部在440nm处最大,平均值达到0.006;总的不对称因子平均值约为0.72;北京地区沙尘天气期间气溶胶粒子谱型成双峰分布,且以粗模态粒子为主,其峰值随光学厚度的增大而增大,粗模态粒子的峰值半径平均约为2.6μm;北京地区的沙尘天气主要集中在春季和冬季,且经过一系列有效的沙尘治理手段,北京地区的受沙尘天气影响的天数呈减小的趋势。(4)北京地区气溶胶光学特性具有很强的季节性变化:春季和冬季的气溶胶光学厚度平均值大于夏季和秋季;北京地区Angstrom指数春季和冬季较小,春季的Angstrom指数平均值最小(0.93),这主要是因为北京地区春季和冬季是沙尘天气的多发季节,有大量的粗沙尘粒子存在造成的;而夏季和秋季主要是人为污染型细粒子气溶胶,所以α较大,分别是1.21和1.12。从AERONET数据反演得到的降水量发现,北京地区降水量较小的春季和冬季对应的气溶胶的光学厚度值较大,降水量较大的夏季和秋季气溶胶光学厚度值相对较小,说明降水对气溶胶冲刷对大气有一定的清洁作用。北京地区气溶胶体积谱分布呈现明显的季节性变化,夏季以细模态粒子为主,且比其他季节的体积浓度都大;春季由于受到沙尘粗粒子气溶胶的影响而呈现以粗模态粒子为主的特点,春季的粗模态粒子的体积浓度最大(0.13μm3μm-2),约是细模态粒子体积浓度的2.5倍。(5)在气候和辐射模型中北京地区的单次散射反照率春夏秋冬四个波段的均值分别为0.90、0.92、0.88、0.86;不对称因子在440、675、870、1020nm四个波段的均为0.66。复折射指数实部为1.52,虚部为0.0118。
[Abstract]:With the development of economy and the acceleration of the process of urbanization, the problem of air pollution in Beijing and its surrounding area is becoming more and more serious, and has a serious impact on the living environment of human. Therefore, it is of vital importance to study the long-term aerosol observation in Beijing and to know the optical characteristics of the aerosol in the atmosphere of air pollution. In this paper, the optical properties of the aerosol in Beijing area are studied by using the interactive data language IDL (Interactive Data Language) processing data in combination with the MODIS data, the CALIPSO data and the AERONET observation network data. First of all, the typical sand-dust weather in March of 2013 is analyzed, and the CALLIPSO and MODIS data are adopted to distinguish the aerosol and the cloud according to the attenuation of the 532 nm wavelength and the SCA method of the two-wavelength signal is used to distinguish the aerosol and the cloud, and then a CLIM method is adopted to further identify the dust aerosol, The results of sand-dust identification are given. The model of HYSPLIT and NAAPS is used to simulate the dust source and the transmission process, and the optical thickness of the aerosol is initially inverted by the double-wavelength inversion method. The optical characteristics of the dust aerosol are then inverted by using the solar direct radiation data of AERONET, and the optical characteristics of the dust aerosol in the sand and dust weather in Beijing area from 2001 to 2013 are analyzed. finally, the optical thickness of the aerosol in the Beijing area is inverted by using the solar direct radiation data of the AERONET, and the optical characteristic parameters such as a single scattering albedo, a complex refraction index and a volume spectrum distribution of the aerosol are inverted by using the sky scattered radiation data, Statistical analysis of the seasonal variation of aerosol optical properties in Beijing from 2002 to 2013. The results are as follows: (1) The spatial distribution of the aerosol and the cloud and the distribution height of the aerosol and the cloud can be obtained from the spatial distribution diagram of each optical characteristic parameter; and the aerosol and the cloud can be better distinguished and the dust aerosol can be identified by combining the SCA and the CLIM method. (2) The results of the analysis of the typical sand-dust weather from March 9 to 11,2013 show that the depolarizing ratio of the dust aerosol is between 0.1 and 0.4, the color ratio is usually more than 0.3, and the distribution height of the dust is generally less than 4km. By using the HYSPLIT model and the NAAPS aerosol model, it is found that this dust originated from the south Xinjiang basin and the central and western part of Inner Mongolia, and is in accordance with the west-west path type in the sand-dust weather transmission path in China. In the process of sand transport, the dust weather has a significant impact on the air quality in Beijing, and the main pollutants are converted from PM2.5 to PM10. In this paper, the optical thickness of the dust aerosol in the dust and dust in Beijing area due to the dust storm is obtained by the double-wavelength iterative inversion method, which is 0.534 and 0.621, respectively. (3) The results of the study on the dust weather in Beijing from 2001 to 2013: the influence of the dust particles during the Beijing dust weather, the large value of the aerosol optical thickness, the decrease with the increase of the wavelength, the maximum at the wavelength of 440 nm and the average value of about 1.2; The aerosol Angstrom wavelength index is 97.62%, which is below 0.7, indicating that the particles are large during the sand-dust weather in Beijing; the single-scattering albedo increases with the increase of the wavelength, the average value is about 0.93; the real part of the complex refractive index is the largest at the wavelength of 675 nm, and the average is about 1.55, the average value of the total asymmetry factor is about 0.72; the average value of the total asymmetry factor is about 0.72; the aerosol particle spectrum type is a bimodal distribution during the dust weather in the beijing area, and the peak value of the aerosol particle is increased with the increase of the optical thickness, The average radius of the coarse-mode particles is about 2.6. m u.m. The dust weather in Beijing area is mainly concentrated in spring and winter, and the number of days affected by the sand-dust weather in Beijing is decreasing. (4) The optical characteristics of the aerosol in Beijing have a strong seasonal change: the average of the aerosol optical thickness in the spring and winter is greater than that in the summer and autumn; the Angstrom index in Beijing is smaller in spring and in winter, and the average value of the Angstrom index in the spring is the smallest (0.93). This is mainly because the spring and winter of Beijing are the multi-season of sand-dust weather, and there is a large number of coarse sand-dust particles, while the summer and fall are mainly artificial pollution-type fine-particle aerosol, so it is relatively large, which is 1.21 and 1.12, respectively. The precipitation in Beijing is relatively small in spring and winter, and the optical thickness of the aerosol in summer and autumn is relatively small. It is indicated that the precipitation has a certain cleaning effect on the atmosphere. The distribution of the aerosol volume in the Beijing area shows a significant seasonal change, with fine-mode particles as the main in the summer and larger than the volume concentration in other seasons; the spring is mainly characterized by coarse-mode particles due to the influence of the dust-coarse-particle aerosol, The volume concentration of the coarse-modal particles in the spring is the largest (0.13. mu.m-m3. mu.m-2), which is about 2.5 times the volume concentration of the fine-mode particles. (5) In the climate and radiation model, the mean value of the single-scattering albedo in Beijing is 0.90, 0.92, 0.88, 0.86, and the asymmetry factor is 0.66 in the four bands of 440,675,870 and 1020 nm, respectively. The real part of the complex refractive index is 1.52 and the imaginary part is 0.0118.
【学位授予单位】：安徽农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X513

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