Abstract : H.2
1D+3DVar assimilation of radar reflectivities in a mountainous area

Olivier Caumont, Véronique Ducrocq, Stéphanie Pradier-Vabre
GAME/CNRM (Météo-France, CNRS)

Through the Arome project, Météo-France aims at merging Aladin's dynamics and Meso-NH's microphysics into a kilometric-scale numerical weather prediction model capable of assimilating new high-resolution data.

In this framework, an original 1D+3DVar assimilation technique is being developed in order to assimilate volumes of radar reflectivities in the Arome model. The first step of the assimilation method itself consists in converting observed reflectivity profiles into humidity profiles with the help of background humidity and simulated reflectivity fields. Then, humidity profiles are assimilated as pseudo-observations with a 3DVar system.

The method has been applied to a flash-flood event which occurred in a mountainous area. On this case, the method outperformed the reference run without assimilation of radar data, but revealed some weaknesses. Work is in progress to identify the origin of these unwanted features so as to mitigate them.