D3.1 Progress on developing the global transport model, data assimilation, and preliminary demonstration of CO2MVS capacity

The global CO2 Monitoring Verification System (CO2 MVS) of the Copernicus CO2 Service will use the Integrated Forecasting System (IFS) at ECMWF to estimate global anthropogenic emissions of CO2 and CH4. This requires the development of the inversion capability in the IFS including CO2, CH4 and co-emitted species, the use of a long window for data assimilation and a mass conserving tracer transport advection scheme. This report describes the progress on these different aspects during the first 12 months of the CoCO2 project. We use case studies, focusing on simulations of plumes and CH4 inversion studies to showcase the capability of the IFS towards the estimation of fossil fuel emissions at global scale. The main achievements presented include: (i) the use of a new interpolation method COMADH resulting in a much better mass conservation of CO2 and CH4 in the tracer transport model; (ii) the implementation of a simplified chemistry tangent-linear adjoint (TL-AD) code in the IFS analysis and inversion system; (iii) a demonstration of the IFS inversion capability with CH4 fluxes for several published case studies.