Assimilating optical and radar data into the STICS crop model for wheat

The STICS crop model was recently coupled with radiative transfer (RT) models in the solar and microwave domains. This permits the simulation of the temporal variation of remotely-sensed data over wheat canopies. This paper presents the first results in assimilating remotely sensed data into STICS: comparing simulated and actual remotely-sensed data allows the recalibration of some STICS parameters so as to constrain the evolution of the simulated canopy variables. A sensitivity analysis of the coupled STICS+RT model was carried out to select the parameters of STICS with the largest influence on remotely-sensed observables and on some canopy variables (dry biomass and LAI), leading us to assess the parameters that should be recalibrated in the assimilation process, in order to adequately simulate the time course of the remotely-sensed data. In a second step, the benefits of assimilating optical data alone, radar data alone and both optical and radar data into STICS+RT were compared.