敦煌地区大气气溶胶对卫星传感器辐射校正的影响

１９９４年６月，利用光谱辐射计在中国西北敦煌西戈壁地区进行了一次大气衰减测量试验。利用测量结果和有关资料，给出了该地区气溶胶光学厚度及其粒子大小谱分布。并将实验结果与我国东部典型地区的气溶胶特性测量结果作了比较，结果表明：敦煌西戈壁地区气溶胶类似于我国东部地区乡村气溶胶模型，并显示出该地区大气中气溶胶大粒子（ｒ≥１．０μｍ）含量占有一定比例。为对即将开展的遥感卫星传感器辐射校正工作作准备，进一步利用模拟计算分析的方法在可见（以０．５５μｍ代表）、中红外（以１０．６μｍ代表）波段，探讨了气溶胶粒子折射指数虚部、粒径大小对气溶胶消光和吸收作用的影响，得到了气溶胶吸收在一般情况下与折射指数虚部呈线性关系及在可见波段对气溶胶消光有影响作用的折射指数应部的变化范围很小的结果。在所给粒径范围（０．０１μｍ≤ｒ≤１０．０μｍ）内，可见波段气溶胶吸收对粒子半径（ｒ）的依赖性较大；气溶胶散射在０．０１μｍ≤ｒ≤０．１μｍ范围内对ｒ的依赖性几乎为线性关系，随ｒ的进一步增大，气溶胶散射和吸收趋于常数。

Effects of Atmospheric Aerosols on the Radiometric Calibration of Satellite Sensors at Dunhuang Site

Atmospheric spectral extinction measurements for the Gobi Desert were performed with a spectroradiometer and a Halon standard reference during June 1994 at the Gobi of Dunhuang,China. Optical thickness and the size distribution of aerosol particles were retrieved from results of the measurements and some related data. The comparison between the results of the measurements and those measured at some eastern parts of China shows that the aerosol model of the site was similar to the rural ones of these eastern parts of China,and also indicates that there is a certain proportion of large particles(r≥1. 0μm)in the atmosphere of this site. A comprehensive sensitivity study has also been made using numerical simulation methods to determine the effects of the variations of imaginary parts of the complex refractive index and particulate size on aerosol extinction for visible(0. 55μm)and thermal IR(10. 6 μm) wavelengths. In general,aerosol absorption is linear with imaginary part of refractive index for relatively largeparticles(for example,r=2. 0μm in the paper). For the range of particle radii(0. 01μm≤r≤10. 0 μm)given in this article,aerosol absorption is stronger dependent on the geometric radius of aerosol particulate for the visible wavelengths,and aerosol scattering is almost linear with it for the range 0. 01μm≤r≤0. 02 μm of radii in the same wavelengths.