Monitoring Vegetation Growth using Multitemporal CHRIS/PROBA Data

The spaceborne ESA-mission CHRIS/PROBA (Compact High Resolution Imaging Spectrometer-Project for On-board Autonomy) provides hyperspectral and multi- directional data of selected targets spread over the world. This coupled system represents a new source of information for Earth observation purposes. While the spectral information content of CHRIS data is able to assess the biochemistry of a vegetation canopy, the directional information can describe the structure of an observed canopy. Both biochemical content and canopy structure change with phenological development. During May to September 2005, numerous spectro-directional CHRIS data sets for six different phenological stages were acquired over a testsite in Switzerland. The area covered is dominated by agricultural fields and forests. A selection of CHRIS data sets that span the observed growing phase were geometrically and atmospherically corrected using a parametric geocoding approach and the physically based atmospheric correction software ATCOR. The analysis of the CHRIS data focuses on the interpretation of HDRF (Hemispherical Directional Reflectance Factor) changes contained in the various data sets over time. The spectrodirectional behaviour of agricultural crops varies over time as a function of vegetation stages (phenology). Understanding of this effect, which is studied on selected crops, may improve agricultural monitoring and crop classification. Accurate spatial mapping of crop status serves as an important input to precision agriculture.