While the mapping of LAI green (LAI G ) is well established, current operational products are not calibrated for LAI brown (LAI B ), i.e. LAI estimation over senescent vegetation. With Sentinel-2 (S2) new opportunities are opened to estimate LAI brown. An explicit distinction between LAI G and LAI B can be achieved thanks to the S2 bands in the red edge (B5: 705 nm and B6: 740 nm) and in the shortwave infrared (B11: 1610 nm). By using LAI ground measurements data from multiple campaigns together with available S2 data, independent LAI G and LAI B models were optimized using Gaussian processes regression (LAI G : R 2 = 0.89, NRMSE= 7.1%; LAI B : R 2 = 0.75, NRMSE= 13.7%). These models can then be combined into LAI GB composite maps. The uncertainty estimates were used to map only those LAI estimated values that fall within a 50% uncertainty threshold. As only the vegetated areas fall within that threshold there is no need to apply additional masks. For multiple European core test sites, LAI GB composite maps were generated from S2 images, enabling to quantify when crops start senescing across the European regions.
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