Assimilation of Geomagnetic Observations: Foundations and Challenges Alexandre Fournier 1 , Thierry Alboussi` ere 1 , Elisabeth Canet 1 , Philippe Cardin 1 , Nicolas Gillet 1 , Dominique Jault 1 , Alexandre Pais 2 1 Laboratoire de G´ eophysique interne et Tectonophysique, Universit´ e Joseph-Fourier, CNRS 2 Center for Computational Physics, Department of Physics, University of Coimbra, Coimbra General Assembly of the European Geosciences Union, 16 April 2008 http://www-lgit.obs.ujf-grenoble.fr/users/vsqg A. Fournier et al. (Universit´ e Joseph-Fourier) Geomagnetic Data Assimilation EGU 2008 1 / 50