4.2统计方法（Statistical methods). Vegetation indices(VI,植被指数)have been used to predict various land surface biophysical variables (y) y=∑a,7 i=0 y=a+bVI y=aln(b-V1)+c 最好用经过大气校正的地表反射率作为计算植被指数的变量
4.2 统计方法（Statistical methods） 0 n i i i y aVI c y a bVI y a b VI c ln( ) Vegetation indices (VI，植被指数) have been used to predict various land surface biophysical variables (y) 最好用经过大气校正的地表反射率作为计算植被指数的变量
Multispectral VI Normalized Difference Vegetation Index (NDVD NDVI= PNIRPR PNIR +PR NDVI与LAI、绿色生物量、植被覆盖度、光合作用等植被参 数有关 LAI=LAI NDVI,-NDVImin max NDVImax -NDVImin (Justice,1986)
Normalized Difference Vegetation Index (NDVI) NIR R NIR R NDVI NDVI与LAI、绿色生物量、植被覆盖度、光合作用等植被参 数有关 min max max min NDVI NDVI i LAI LAI NDVI NDVI (Justice,1986) Multispectral VI
5ep时ember21,1998 全球NDVI (植被指数)
全球 NDVI (植被指数)
Absorbed photosynthetically active radiation APAR=93.5[1-exp(-0.9LAI)] (Asrar et al.,1984)
APAR LAI 93.5[1 exp( 0.9 )] Absorbed photosynthetically active radiation (Asrar et al., 1984)
Simple Ratio (SR) SR=PNIR PR SR-1 2 NDVI= =I- SR+1 SR+1
Simple Ratio (SR) NIR R SR 1 2 1 1 1 SR NDVI SR SR