disponibles pour les 30 ans avant ce jour, ou, si ces données pluviométriques ne sont pas disponibles ...

"The normal rainfall data used is the average determined by taking the arithmetic mean of the historical satellite-based rainfall for each dekad and grid point,
for the available rainfall in the preceding thirty years as of today,
or, if thirty years are not available"

"At every half-hour interval dot product of the terrain slope and wind is computed. The scalar product of the surface wind vector (u(x,y),v(x,y)) and the horizontal gradient of orography gradient [h(x,y)] i.e.

is approximated by finite differences centered at the grid points. The dot product values are then interpolated to a grid with the same resolution as the Meteosat data and finally it is multiplied by the analyzed surface relative humidity in order to incorporate the orographic lift of low-level moisture. Every half-hour for each grid point, where the cloud top temperatures ranges from 235 to 275K, the product of the surface relative humidity and the dot product is stored. The product is then summed for ten-day period and calibrated with the raingauge values to be used for estimation of rainfall from warm cloud. "
http://www.punchdown.org/rvb/rain/NurThesis.html