The VENµS L2A and L3A surface reflectance products

To allow a robust exploitation of the information provided by VENµS, users must have access to high quality time series of surface reflectance. It is therefore necessary to remove the disturbing effects of the atmosphere. This is the role of the Level 2A product, which includes an accurate and robust cloud detection, and corrects data from atmospheric effects due to variable aerosol content. Compared to classical processors based on multi-spectral relations to detect clouds and estimate aerosol content, the Maja processor - used for VENµS L2A computation - also involves multi-temporal criteria based on the fact that land surface reflectance tends to change slowly compared to the atmospheric contribution. A large scale validation effort has been done to measure the accuracy of the L2A products generated with MAJA, regarding cloud detection accuracy, validation of Aerosol optical thickness of surface reflectances.

But even with accurate surface reflectance and cloud masks, such products are still complicated to use for non specialists. The presence of clouds causes spatial and temporal data gaps in the time series and processing method must be robust to that, which is complex. Overcoming this difficulty is the role of the L3A product, which, for VENµS, provides a bi-monthly synthesis of cloud free surface reflectance.

Our presentation details the methods behind MAJA and L3A processors and details their validation results.