This report was published by Thibaut Montmerle, Claude Fisher and LoÃ¯k Berre on February 2005.
It presents the aim, strategy and first results for the implementation of an operational variational data assimilation systelm in the ALADIN/France model. Starting from the experience gathered over the last five years with 3D-VAR in ALADIN as a research configuration, the goal is to settle a continuous, permanent assimilation cycle with an initial update fraquency of 6 hours.
A discussion concerning the choice of the background error covariance matrix is presented. Emphasis is furthermore made on the specific use of SEVIRI data and on their impact on precipitation forecasts at mesoscale.
Spin-up characteristics of proposed data assimilation cycle then future work and references are presented.