Toward a Near-Real-Time Surface Flux Update for Atmospheric Composition at ECMWF

The European Union’s Copernicus Atmosphere Monitoring Service (CAMS) operationally provides daily forecasts of global atmospheric composition. It uses the ECMWF Integrated Forecasting System (IFS), which includes meteorological and atmospheric composition variables, such as reactive gases, greenhouse gases and aerosols, for its global forecasts and reanalyses. With atmospheric composition being as much a boundary condition problem as an initial condition problem, there is a strong need to constrain surface fluxes in addition to the 3D representation of atmospheric variables. In this presentation, we will show the implementation plans and advances of the surface flux inversion suite to provide real-time surface flux updates jointly with the current atmospheric updates (i.e. tracers and NWP variables), given constraints on the IFS and the observation streams available. We will emphasize the efforts to update the CAMS system to an Ensemble of Data Assimilation (EDA), i.e. running an ensemble of 4D variational analysis updates and subsequent forecasts. The results show how the ensemble information in a variational framework can be used to update surface fluxes in a near real time cycling analysis.