A GPS network for tropospheric tomography in the framework of the Mediterranean hydrometeorological observatory Cévennes-Vivarais (southeastern France) oleh H. Brenot, A. Walpersdorf, M. Reverdy, J. van Baelen, V. Ducrocq, C. Champollion, F. Masson, E. Doerflinger, P. Collard, P. Giroux