Modeled snow cover in pyrenees mountains and cross-comparisons between remote-sensed and land-based observation data
Durand, Yves ; Giraud, Gérald ; Goetz, Daniel ; Maris, Malou ; Payen, Valentin
Only few studies have already attempted to assess the distribution and magnitude of seasonal snowpack under the varying climate of the Pyrenees. In using modeling tools (SCM chain), Météo-France/CEN has generated a distributed climatology of the main meteorological and snow parameters at the spatial scale of the massif for the Pyrenees over the period 1958-2008. This work aims at validating it for different research uses. In particular, in the framework of the FluxPyr Project, a new study was conducted using MODIS snow satellite data over Pyrenees which gave the opportunity to perform a lot of cross comparisons during the last ten years and thus to complement the other classical validations. The MODIS information of snow cover coverage was compared to a corresponding modeled value obtained by a downscaling procedure. All results are then shown globally over the whole period in order to filter the downscaling noise and the small-scale effects over the computation grid which is also used for the comparisons with the data from the manual snowweather observation network. The results show a close agreement between all involved information sources (> 80% between MODIS and SCM). The main discrepancies occur in the vicinity of the low elevations of the continuous snow cover (~60%), especially in the most eastward massifs. In addition the forest areas do not exhibit more differences that the forest free ones. The human observations are always close of the MODIS data (92% for snow occurence) and of SCM (89% for snow occurrence and 71% for depth).
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