本文利用1988年9月黑河实验预试验期晴天AVHRR资料分析了实验区反射率观测值和植被指数对卫星观测角的依赖关系,讨论了应用Taylor和Stowe的各向异性订正函数对反射率观测值进行订正的效果及存在的问题。分析结果表明:Taylor和Stowe的订正函数的应用有较好的订正效果,但对高反射率的戈壁沙漠和低反射率的山地森林地区仍存在一定偏差。植被指数基本上不依赖于卫星观测角,但观测区处在星下点附近时测得的植被指数值要比远离星下点时大一些。

AVHRR data for clear skies over the Heihe experimental area during the pilot experiment period in September, 1988 are used to investigate the effect of the satellite observing angles on the reflectance and vegetation index measurement. The anisotropic factors over land areas given by Taylor and Stowe (1984) are used for the correction. The study shows that the application of the anisotropic correction leads to quite good results, but some bias still exist for high albedo areas, such as Gobi-desert and for low albedo area such as mountain forest. Vegetation index is generally independent of the satellite observing angles, but for the same region, the vegetation indexes derived when the region is near the sub-satellite point are a little higher than those derived when the region is far from the sub-satellite point.