Diagnosis of observation, background, and analysis error statistics in observation space
Diagnostique d'erreur d'observation, de données de départ et statistiques d'erreur d'analyse dans l'espace d'observation
Desroziers, G. ; Berre, L. ; Chapnik, B. ; Poli, P.
Année de publication
2005
Abstract</h3><p align="justify">Most operational assimilation <br>schemes rely on linear estimation theory. Under this assumption, it is <br>shown how simple consistency diagnostics can be obtained for the <br>covariances of observation, background and estimation errors in <br>observation space. Those diagnostics are shown to be nearly cost-free <br>since they only combine quantities available after the analysis, i.e. <br>observed values and their background and analysis counterparts in <br>observation space. A first application of such diagnostics is presented <br>on analyses provided by the French 4D-Var assimilation. A procedure to <br>refine background and observation-error variances is also proposed and <br>tested in a simple toy analysis problem. The possibility to diagnose <br>cross-correlations between observation errors is also investigated in <br>this same simple framework. A spectral interpretation of the diagnosed <br>covariances is finally presented, which allows us to highlight the role <br>of the scale separation between background and observation errors. <br></p><p align="justify">Copyright © 2005 Royal Meteorological Society</p>
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