hardly distinguishable from the surface signature. Thus, a small signal from the atmosphere may remain in our 
data but the main signature is generated by the surface. 
The method we used in this study to process POLDER data matches in part that which is envisioned for the 
opertational processing of spacebome POLDER data. Our results give confidence in the soundness of the 
method, especialy since spacebome measurement registration will have a much better relative accuracy. The 
POLDER instrument on ADEOS will provide a global estimate of surface reflectance directional signatures at 
resolution 6x6 km. With the method described above, POLDER measurements yield a reflectance corrected for 
angular effects, which is well suited for a quantitative monitoring of the surface. 
ACCNOWLEDGMENTS 
The POLDER instrument has been designed, built, serviced and operated by the Laboratoire d’Optique 
Atmosphérique (LOA), Lille, France, with a sponsorship from the Centre National d’Etudes Spatiales (CNES). 
We acknowledge the work of many individuals from this laboratory who participated to the “La Crau-91” 
experiment and made this study possible, and in particular J.Y. Balois, C. Devaux, M. Herman and C. 
Verwaerde. The help from several personel from CNES and INRA was also appreciated. The POLDER 
airborne campaign, placed under the responsibility of A. Podaire, was made possible by a sponsorship of the 
Programme National de Télédétection Spatiale (PNTS). 
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