5.5 Algorithms

The retrieval of FVC, LAI and fAPAR in the LSA SAF rely on Spectral Mixture Analysis (SMA); the signal from a single pixel (surface reflectance) is assumed to be the contribution of different vegetation and bare soil components within the scene (next figure).


As detailed in Chapter 2, the surface BRDF may be written as:

ρ (θs, θv, φ) = K0 + K1 x F1s, θv, φ) + K2 x F2s, θv, φ)


    K0 - represents isotropic reflectance;
    K1 - represents geometric reflectance;
    K2 - represents volumetric reflectance;

Parameters K0 in the SEVIRI channels VIS 0.6 μm, VIS 0.8 μm and NIR 1.6 μm are used to determine FVC and LAI, while fAPAR uses K0, K1 and K2.