Improving winter wheat yield estimation by assimilation of the leaf area index from Landsat TM and MODIS data into the WOFOST model

•We examined wheat yields by assimilating LAI from Landsat TM and MODIS data.•Four-dimensional variational data assimilation improved the yield estimates.•Correcting for scale greatly reduced the root-mean-square prediction error.•Key phenological LAIs and a pixel purity threshold must be used for data assimilation.