气溶胶论文：气溶胶光学厚度Angstrom参数浓度分布拟合半干旱区SACOL

【关键词】气溶胶光学厚度 Angstrom参数浓度分布拟合半

干旱区 SACOL

【英文关键词】Aerosol Optical Depth Angstrom

parameter mass concentration number

concentration number size distributions fitting semi-arid region

气溶胶论文：西北半干旱区气溶胶光学和物理特性的观测研

究

【中文摘要】大气气溶胶在大气中的行为、转化及其对气候、环

境和人体健康的影响,不仅取决于其在环境大气中的浓度,还与其粒

径大小、粒谱分布、光学特性、化学组成和在大气中的寿命等因素有

关。因此,探究气溶胶颗粒物的光学和物理特性,有助于深入研究气溶

胶颗粒物的气候效应和环境行为。利用兰州大学半干旱气候与环境观

测站(SACOL)在2010年1月-2011年2月多种仪器观测的综合数据,

分析了气溶胶光学参数、不同粒径段气溶胶数浓度和数谱分布随时间

变化的特点,以及气象条件对这些参数的影响,讨论了AOD与PM1o质

量浓度的相关性。同时,探讨了用APS资料拟合PM1o质量浓度的方法,

主要结论如下：SACOL站气溶胶光学厚度、浑浊度系数以及波长指数

的年均值依次为0.410、0.231、0.840,前两个光学参数的季节均值

按春、冬、夏、秋顺序依次减少,波长指数的季节均值则按春、冬、夏、秋依次增大。SACOL站大气中气溶胶总数浓度主要取决于PM2.5数浓度,特别以粒径小于1.0μm的积聚模态居多,其中冬季粒径小于1μm的气溶胶粒子数浓度又远高于其它季节。PM2.5、PMcoarse、PM10-20三者数浓度的季节均值都是在冬季最大,夏季最小。春季沙尘天气的频繁发生和冬季燃煤取暖使春冬季节成为SACOL站气溶胶污染的主要季节。SACOL站常年盛行东南和西北风,从这两个方向输送来的气溶胶粒子、数浓度出现高值的次数最多。冬季,SACOL站西北方向人类活动产生的污染物明显多于东南方向。SACOL站相对湿度的变化对AOD大小的影响不明显,AOD与PM1o质量浓度的相关程度不高。2010年春季,SACOL站沙尘天气频繁发生。沙尘天气和降水天气过程中气溶胶特性变化显著。沙尘天气中,AOD增大,浑浊度系数与AOD变化趋势保持一致,呈正相关关系,波长指数与它们呈较弱的负相关。在一次沙尘天气过程中,PM2.5、PMcoarse和PM10-20的数浓度变幅剧烈,三者出现最大值的时间各不相同：沙尘暴发生前,PM2.5数浓度急剧增大,气溶胶总数浓度主要取决于粒径小于0.523μm的颗粒物数浓度；沙尘暴出现时,PMcoarse数浓度急剧增加,PMtotal质量浓度主要取决于PMcoarse数浓度。在春季一次降水过程中,降水对PM2.5、PMcoarse以及PM10-20的湿沉降非常明显,总体沉降效率达到96.4%。用APS数据拟合PM1o质量浓度的方法中,一元线性回归和多元线性回归在春季沙尘天气和冬季污染天气条件下的相关系数都

超过了0.950,因此这两种方法都适用于SACOL站这两种天气条件下的拟合。从理论和实际结果两方面来看都是多元线性拟合结果更好,所以用APS测量出气溶胶粒子数浓度后,可选用合适的多元线性拟合方程计算质量浓度。

【英文摘要】The features of atmospheric aerosols, such as the transformation and long distance transport, and the effects on climate change, environment and human health, not only depend on the concentration, but also link to particle size distributions, optical properties, chemical composition, lifetime, and so on. In order to further understand the optical and physical properties of aerosols, some fundamental studies are necessary.The characteristics of aerosol optical parameters, particle sizes range of aerosol number concentration and the number of spectral distribution were analyzed, using the observational data collected at SACOL from January2010to February2012. The relationship between the parameters mentioned above and meteorological conditions, and the correlation between AOD and mass concentration of PM10were discussed as well. Meanwhile, the data-fitting between APS data and PM10mass concentration was explored. The main conclusions are as follows:The annual average of aerosol optical depth,

turbidity coefficient, wave length exponent

are0.410,0.231and0.840respectively. The seasonal averages of first two optical parameters are progressively decreasing, in order of spring, winter, summer, and autumn over SACOL, but the seasonal averages of wave length exponents are opposite. The aerosol total concentrations over SACOL mainly depend on number concentrations of PM2.5, especially as the particle size less than1.0μm (in the accumulation of mode) is in the majority. Among them, the number concentration of aerosol particles with size less than1μm in winter is far beyond in other seasons. The seasonal average of PM2.5, PMcoarse, PM10-20, reach to the maximum in winter, and minimum in summer. The frequent occurrence of spring dust weather and winter coal-fired heating may lead to heavy aerosol pollution in spring and winter over SACOL.Southeast and northwest wind are main directions in SACOL. In winter, pollutants derived from human activities in northwest are more than that in southeast. The effect of relative humidity on AOD is not obvious, and degree of correlation between AOD and mass concentration of PM10is not significant.Dust events occurred frequently in SACOL area in the spring of2010. The characteristics of aerosol had been