大气气溶胶光学特性与遥感图像光谱相关性分析

大气气溶胶对气候变化有重要的影响,由于观测资料缺乏,遥感成为越来越重要的研究手段。通过对气溶胶粒子的散射和反射特性分析表明,气溶胶的光学特性因气溶胶的成分和入射光波长的不同而不同,利用这些光谱差异,可以通过遥感方法进行光学厚度的反演,进而研究气溶胶的运动及分布、气候效应等特征。气溶胶中不同的粒子尺度及组成使其散射光学特性有较大的差异,2.1μm(或2.2μm)波段处的光谱反射率受尘粒气溶胶的影响较大;气溶胶具有时空变异特征;气溶胶在大气层上界(TDA)的辐射强迫表现为正效应,在单粒子反射率(SSA)的某一区间,其净效应因云状大小、表面反射率以及垂直气溶胶和云的分布的变化而变化,它通过影响云的凝聚核和半向效应而具有间接辐射强迫效应,另外它与臭氧的含量具有密切关系;在气溶胶信息的获取中,太阳光度计观测是一种重要手段,遥感正成为研究气溶胶越来越重要的途径。

A Study on Integral Optical Characteristic of Atmospheric Aerosols

The impact of aerosols can lead to a large regional cooling on the earth' s surface. This paper reviews the recent research results on the aerosol spectrum characteristics, retrieving method, effect of radiation forcing and the main measures. On account of the difference of aerosol particle-size and component, its scattering albedo is also different, and dust aerosols exert great effect on the 2.1μn or 2.2μm spectrum reflectance ratio. Also, aerosols have great spatial and temporal variabilities. There is a positive effect of top-of-atmosphere (TOA) aerosol radiative forcing, the net effect can change from negative to large positive forcing depending on the cloud fraction, surface albedos as well as changes of vertical aerosols and cloud distribution. Meanwhile, aerosols affect radiative forcing by providing the nucleus most cloud drops and ice crystals and semidirect effect on clouds, and there is a close connection between the increase of aerosols and the decrease of ozone. Sunphotometer is one of the most common surveying instruments, which is used to contrast or revise the observing results by satellite sensors. At present, remote sensing is getting more and more important.