Anny A Cazenave¹, Florence Birol², Marcello Passaro³, Fabien Leger², Yvan Gouzenes², Philippe Rogel⁴, Jean Francois Legeais⁵ and Jérôme Benveniste⁶, (1)Laboratoire d'Etudes en Geophysique et Oceanographie Spatiale, Observatoire Midi Pyrénées, LEGOS-CNES-CNRS-IRD-UPS, Toulouse, France, (2)LEGOS, Toulouse, France, (3)Technical University of Munich, Munich, Germany, (4)CERFACS European Centre for Research and Advanced Training in Scientific Computation, Toulouse, France, (5)CLS, Ramonville St Agne, France, (6)European Space Agency (ESA-ESRIN), Earth Observation Programmes, Frascati, Italy