Validation of POLDER surface albedo products based on a review of other satellites and climate databases

This study is devoted to a global verification of the reliability of the POLDER-derived BRDF and albedo products over land surfaces based on an exhaustive review of similar existing products. A global comparison of POLDER albedos is carried on at 0.5 degree resolution with satellite-derived products and Numerical Weather Prediction (NWP) models. In general, a large underestimate of the albedos from climate databases are noticed over desert and semi-desert regions. Also, large discrepancies are noticed for snow. NWP albedos show overestimates of 0.4 over mountainous regions, compared to either POLDER or MODIS. Reverse trend is observed at high latitudes for snow beneath forest canopies. As a conclusion, it comes out the multi-angular capabilities offered by POLDER yields a unique tool to estimate surface albedo within an the accuracy required by the users.