Since March 2002, the GRACE mission provides monthly global maps of geoid time-variations. These new data carry information on the continental water storage, including snow mass variations, with a ground resolution of ~600-700 km. We have computed monthly snow mass solutions from the inversion of the 22 GRACE geoids (04/2002 -05/2004). The inverse approach developed here allows to separate the soil waters from snow signal. These snow mass solutions are further compared to predictions from three

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... global land surface models and snow depths derived from satellite microwave data. We find that the GRACE solutions correlate well with the high-latitude zones of strong accumulation of snow. Regional means computed for four large boreal basins (Yenisey, Ob, Mac Kenzie and Yukon) show a good agreement at seasonal scale between the snow mass solutions and model predictions (global rms ~30-40 mm of equivalent-water height and ~10-20 mm regionally).