大气颗粒物PM_(2.5)的消光特性研究

Research on Extinction Characteristics of PM_(2.5) in Air Suspended Particles

基于Mie散射理论,对大气颗粒物PM2.5的消光特性进行了研究,建立了混合颗粒系统消光系数的理论及等效计算方法.计算表明,不像大颗粒,PM2.5单颗粒的消光效率因子强烈地依赖于折射率和粒径;多颗粒的消光系数随粒度增加而增大,在强吸收时,也随分布宽度增加而增大;其随波长的变化与折射率、分布有关,往往是非单调的,而对混合的颗粒系统,还与混合比有关.分析表明,我们提出的消光系数的理论及等效计算方法也为实际大气颗粒物的光学特性研究提供了一个新的研究手段.

Based on Mie theory, the extinction characteristics of PM2.5 in air suspended particles have been studied in this paper. The theoretical calculation and its equivalent method for the extinction coefficients of the mixing particles have also been provided. The calculations show that the extinction effieiency factor of single PM2.5 partiele depends highly on the refractive index and particle size, while the extinction coefficients of a group of particles increase with the particle size, and even with the width of distribution in the case of strong absorption. Changes of the extinction coefficient with the wavelength, usually not monotonous, relate to the refractive index and particle size distribution, and also to the mixing ratio for the mixing particles. A new potential way is provided for studying the optical characteristics of actual air suspended particles.