Table 2 - POLDER measurements of the NDVI, of the polarized reflectance at 650 nm (in percent) and of 
the BRDF at 650 nm ( anti-specular/specular) 
NDVI 
polarization 
BRDF 
0.56 
0.27 
3.2 
sorghum 
0.29 
1.21 
1.0 
rize 
0.79 
0.51 
1.6 
com 
0.76 
1.10 
0.94 
sunflower 
0.56 
0.12 
2.68 
vine 
0.56 
0.00 
1.60 
wheat 
0.80 
0.07 
1.04 
orchard 
The results reported is table 2 are to limitated in number to be representative but some 
indications can be derived: the rize presents a low NDVI because of a significant contribution of the water 
certaintly correlated to a large specular polarized component. For the same NDVI, a structure in row 
presents a small polarization with an expected high 'hot spot'. A planiform structure of a canopy exhibits 
a large polarization. 
4 CONCLUSION 
Observed from space, the polarized reflectance has both an atmospheric origin and a contribution from 
the ground. The relative weight of these two contributors is variable with time ( aerosol loading), with 
the type of surface and with the geometry of observation. Around the specular direction, for high spatial 
resolution sensors, we illustrated the presence of the surface contribution and its variability depending on 
the stage of the vegetation cycle and of the structure of the canopy. We also indicated how to correct the 
space observations for the atmospheric contamination. A more extensive analysis for a possible 
information on agricultural inventory has to be conducted based on others avalaible campaigns. 
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