相对湿度对大气气溶胶消光系数的影响

消光系数是气溶胶颗粒物光学性质的关键参数之一。基于Mie散射理论和气溶胶颗粒粒径及折射率的湿度增长模型,本文详细研究了气溶胶吸湿性对其消光系数的影响。计算结果表明:当入射光波长为808nm、相对湿度在60%~95%之间增加时,因颗粒粒径的增长及折射率的减小,导致颗粒物消光系数曲线右移且其波动性更加明显;而对于同一球形颗粒,小粒径颗粒的消光系数随相对湿度的增加呈指数规律增大,较大粒径颗粒的则表现为波动减小趋势。此外,在不同入射光条件下,小颗粒消光系数与相对湿度之间的关系保持不变。本文的计算结果对气溶胶光学性质与大气环境质量的研究具有一定的参考价值。

The Effect of Relative Humidity on the Extinction Coefficient of Aerosols

The extinction coefficient is one of the critical parameters of the aerosols optical properties.In this study,the influence of relative humidity on the extinction coefficient of spherical particles has been carefully investigated,based on combining the Mie scattering theory with the humidity growth model of the particle size and the refractive index.The results indicate that the particle size increases and the refractive index decreases with the increase of relative humidity in the range 60％-95 ％ when the incident wavelength is 808 nm,which leads to the right shift of the extinction coefficient curve as well as the more obvious fluctuation of the curve.Furthermore,the extinction coefficient of small particles exponentially increases with the increase of relative humidity,while that of the larger particle decreases with small fluctuations.In addition,the law between the extinction coefficient and the relative humidity for small particles remain unchanged under different incident light conditions.The results of this work provide an important theoretical guidance for the study of the optical properties of aerosols and the atmospheric environmental quality.