Ana Fernandez del Rio , Deutscher Wetterdienst (DWD)

Data Assimilation for NWP with the ICON Global Model

Andreas Rhodin, Alexander Cress, Harald Anlauf, Robin faulwetter, Jaison Ambadan, Roland Potthast


The ICON (ICOsahedral Nonhydrostatic general circulation) global model was developed jointly by the German Weather Service (Deutscher Wetterdienst, DWD) and the Max Planck Institute for Meteorology (MPI-M), and is used operationally for Numerical Weather Prediction (NWP) at DWD since January 2015. A hybrid En-Var data assimilation scheme has been developed, and it replaced the previous deterministic 3D-Var in operations in January 2016. The current system, which uses a Local Ensemble Transform Kalman Filter (LETKF) to make the uncertainty flow dependent, will be described. The three data assimilation methods (deterministic 3D-Var, ensemble based LETKF and hybrid En-Var system combining both) will be compared, illustrating how they work differently and assessing the performance of medium range forecasts in a fully operational setup.

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