Impacts of model parameter uncertainties on crop reflectance estimates: a regional case study on wheat

This Letter is an attempt to establish the impact of uncertainty on crop st ructure and soil background on the canopy reflectance estimate thanks to a regional field experiment through which the space and time variability is w ell known. The error due to the use of standard values is mainly due to soi l reflectance in the early growth and to crop structure in the late growth. Vegetation indices, NDVI or TSAVI, reduce the sensitivity to the uncertain ty on both parameters depending on the phenological period.