A hyperspectral multispectral algorithm for fluorescence and reflectance retrieval from space

A model inversion by optimization was investigated for very small (less than 1% of the total sensor radiance) fluorescence signal retrievals from space. For this reason, the retrieval was done in special spectral regions (atmospheric absorption bands) in which solar radiation is attenuated. For the simulations we considered a complete model system of coupled radiative soil-canopy radiation. A four-stream atmospheric flux (i.e. direct solar flux, diffuse downward flux, diffuse upward flux, direct observed flux) at very high spectral resolution (0.1 cm-1) was used for the retrieval of the canopy chlorophyll fluorescence. Only one mathematical function was contemporarily used to fit fluorescence in both the oxygen A and B windows (multispectral fitting) .