On the potential of CHRIS/PROBA for estimating vegetation canopy properties from space

The Compact High Resolution Imaging Spectrometer (CHRIS), to be launched on board the PROBA (Project for On‐Board Autonomy) satellite in 2001/2002, will provide remotely‐sensed data for terrestrial and atmospheric applications. The mission is intended to demonstrate the potential of a compact, low‐cost, imaging spectrometer when combined with a small, agile satellite platform. CHRIS will provide data in 18–62 user‐selectable spectral channels in the range 400 nm to 1050 nm (1.25 nm ‐ 11 nm intervals) at a nominal spatial resolution of either 25 m or 50 m. Since PROBA can be pointed off‐nadir in both the along‐track and across‐track directions, it will be possible to use CHRIS to sample the Bidirectional Reflectance Distribution Function (BRDF) of the land surface. This combination of an agile satellite and a highly configurable sensor offers the unique potential to acquire high spatial resolution, spectral BRDF data sets and, from these, to study the biophysical and biochemical properties of vegetation canopies. It will also provide an important means of validating similar data sets from other, coarser spatial resolution sensors, such as VEGETATION, POLDER2, MODIS and MISR. This paper presents key features of the instrument, and explores the potential of CHRIS for estimating canopy biophysical parameters from space by means of a LUT‐based BRDF model inversion scheme.