Thomas Gastaldo;
Virginia Poli;
Chiara Marsigli;
Tiziana Paccagnella;
Pier Paolo Alberoni
University of Bologna and Regional Agency for Prevention, Environment and Energy (Arpae) of Emilia-Romagna
The 8th EnKF Data Assimilation Workshop
Impact of the observational error in the assimilation of radar reflectivity volumes
Talk:
Gastaldo_presentazione.pptx
At Arpae, the HydroMeteorological Service of Emilia-Romagna Region (Italy), it is operational an ensemble data assimilation system at the convection permitting scale (KENDA), based on the LETKF scheme. The system has been been developed for the Consortium for Small scale Modeling (COSMO) model and, in the current set-up, it is used to assimilate only conventional observations. To fully exploit the potential of KENDA, non conventional data have to be employed. In particular, at Arpae are on-going tests to evaluate the impact of the assimilation of reflectivity volumes from the Italian radar network. A set of experiments shows that a crucial role in determining the quality of the analysis is played by the observational error. This is influenced by three sources: instrumental error, representativity errors and observation operator errors. Since none of these are known, the choice of its value is not straightforward. To estimate the observational error, a diagnostic based on statistical averages of observations-minus-background and observations-minus-analysis residuals is used. This is perfomed separately for each radar since the Italian radar network is inhomogeneous both in the acquisition strategy and from an instrumental point of view. Results both in the assimilation and in the forecast cycle are presented.
At Arpae, the HydroMeteorological Service of Emilia-Romagna Region (Italy), it is operational an ensemble data assimilation system at the convection permitting scale (KENDA), based on the LETKF scheme. The system has been been developed for the Consortium for Small scale Modeling (COSMO) model and, in the current set-up, it is used to assimilate only conventional observations. To fully exploit the potential of KENDA, non conventional data have to be employed. In particular, at Arpae are on-going tests to evaluate the impact of the assimilation of reflectivity volumes from the Italian radar network. A set of experiments shows that a crucial role in determining the quality of the analysis is played by the observational error. This is influenced by three sources: instrumental error, representativity errors and observation operator errors. Since none of these are known, the choice of its value is not straightforward. To estimate the observational error, a diagnostic based on statistical averages of observations-minus-background and observations-minus-analysis residuals is used. This is perfomed separately for each radar since the Italian radar network is inhomogeneous both in the acquisition strategy and from an instrumental point of view. Results both in the assimilation and in the forecast cycle are presented.
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