Using harmonic analysis of green LAI time series obtained from Sentinel-2 imagery for daily representation of crop growth in a hydro-agroecological model

Harmonic Analysis of Time Series (HANTS) was used to obtain daily reconstructed values of green leaf area index (GLAI) from optical Sentinel-2 imagery for a maize and a winter wheat field plot in Southern Germany in order to represent crop growth in the hydro- agroecological PROMET model. Daily GLAI time series were retrieved with high accuracy in case of winter wheat (R2=0.90, RMSE=0.78 m2/m2) and slightly lower accuracy in case of maize (R2=0.85, RMSE=1.05 m2/m2) from the imagery by radiative-transfer model inversion. Assimilating these reconstructed GLAI time series into PROMET using the model forcing technique allowed for retrieving winter wheat fruit biomass (R2=0.98, RMSE=0.08 kg/m2) as well as maize above-ground biomass (R2=0.97, RMSE=0.12 kg/m2) with considerable high accuracy. The proposed approach offers opportunities for contiguous crop growth monitoring as well as biomass and yield modelling.