Name

Professor Heikki Järvinen, University of Helsinki, Finland

Title

Continuous Data Assimilation at ECMWF in IFS CY46

Abstract

A new configuration of the European Centre for Medium-Range Weather Forecasts  (ECMWF) incremental 4D-Var data assimilation (DA) system is discussed which builds upon the quasi-continuous DA concept proposed in the mid-1990s. Rather than working with a fixed set of observations, the new 4D-Var configuration exploits the near-continuous stream of incoming observations by introducing recently arrived observations at each outer loop iteration of the assimilation. This allows the analysis to benefit from more recent observations. Additionally, by decoupling the start time of the DA calculations from the observational data cut-off time, real-time forecasting applications can benefit from more expensive analysis configurations that previously could not have been considered. For real-time forecasting applications, the Continuous DA framework allows configurations which clearly outperform the best available affordable non-continuous configuration. Continuous DA became operational at ECMWF in June 2019 and led to significant 2 to 3% reductions in medium-range forecast root mean square errors, which is roughly equivalent to 2–3 hours of additional predictive skill.

Tid

Thursday December 9, 14:15-15:15    

Place

C609 Rossbysalen, MISU, Svante Arrhenius väg 16C, 6th floor

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