Earth reflectances are highly anisotropic. The most anisotropic signal is observed over water surfaces where the glint effect generates a reflectance that varies by several orders of magnitude as a function of the observation geometry. Over land surfaces, the variations are not as large, but nevertheless significant. The reflectance of a given target varies with the observation geometry by a factor of up to four. This anisotropy causes some difficulties for a quantitative analysis of satellite measurement time series as the variability due to the changing measurement geometry may be as large as the geophysical signal that is monitored.

The POLDER/Parasol spaceborne instrument is a great tool to monitor these effects. Indeed, it provides up to 16 measurements of the same targets, with varying view angles, as the satellite flies over it. We will present and discuss the directional reflectance measurements, and the model that was developed to reproduce the observed signatures. The model is then used to correct the time series, for a much better identification of the geophysical signal, such as the vegetation dynamic.

Location: Physics Bldg., Room 401
Coffee: 3:15 p.m.