叶面积指数(Leaf Area Index)可用来反映作物的生长状况,常作为主要指标应用于农作物估产。本文研究遥感中常见的混合像元问题对LAI反演所带来的不确定性问题。研究的混合像元由两种情况构成,一种是由不同长势的作物所构成的混合像元,另一种情况是由不同端元形成的混合像元。结果表明,不同长势形成的混合像元对LAI的准确反演影响不大;不同组分形成的混合像元对LAI反演影响很大。从验证的角度讲,地面实测点的LAI数据不能代表一定分辨率区域的LAI的值,对于像元LAI的验证要注意正确获得像元的LAI。

Leaf area index(LAI) is the fundamental index to indicate vegetation growth and it can be effectively used in agricultural yield estimation.In this paper,we investigate the LAI inversion uncertainty from mixed pixels.There are two situations for the mixed pixels: one is the pixel mixed with crop of different growth stages;the other is the pixel mixed with different components.The result shows that the accuracy of LAI inversion is almost not affected by different corn growth condition.On the other hand,the impact of mixed pixel on the LAI validation is clear.Field LAI measurements of some points don't stand for the pixel LAI when the pixel consists of crops of different growth.In this situation,we should be cautious for validation of inverted LAI.