Analyzing uncertainties in simulated canopy reflectance through exhaustive comparison with in-situ measured optical properties

The aim of this study is to find a relationship between phenology of winter wheat canopies and the structure parameter N by inversion of the PROSAIL model. In the course of a field campaign conducted in 2014, 11 parameters of canopy architecture and leaf optical properties were measured. Spectral signatures were recorded simultaneously. PROSAIL spectra resulting from the measured parameters were subsequently compared to the measured reflectances. A numerical optimization was performed in which noise was added to most parameters. At the same time, N was increased stepwise to find its best performing value. Deviations between modelled and measured spectra were higher for the original dataset in comparison to the optimized one. A tendency towards higher deviations at states of senescence could be shown. The optimized values for N increased over the season, but a significant trend could not yet be verified for regression against phenology.