IMPLEMENTATION OF A NEW ASSIMILATION SCHEME FOR

SOIL AND SURFACE VARIABLES IN A GLOBAL NWP MODEL

by D. Giard and E. Bazile

   Major changes have been introduced in the description of the soil-atmosphere-vegetation interactions in the global Numerical Weather Prediction model ARPEGE and the embedded Limited Area Model ALADIN used at Météo-France. The ISBA parameterization is now used to describe exchanges between the atmosphere and the land surface. The analysis scheme for soil moisture has been changed accordingly and is now based on an optimal interpolation type using two meter observations of temperature and relative humidity. Additionally, the description of land surface and vegetation characteristics has been improved by the use of new datasets. The overall impact of these modifications is a clear improvement in the forecast of low-level fields and of the global hydrological cycle.

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