Significant progress has been made in understanding the origins and evolution of mass conservation errors in the global CO2MVS IFS advection scheme, particularly in relation to various atmospheric tracers relevant to CO2MVS. Such findings have enabled the identification of areas for improvements within the core algorithms of the IFS advection scheme, leading to a noticeable reduction in mass conservation errors. Furthermore, analysis across a wide range of case studies— from academic case studies to comprehensive greenhouse simulations under accurate emission protocols developed in WP7 — has demonstrated that the optimized configuration of the IFS advection scheme developed by CATRINE can accurately transport atmospheric tracers, when mass errors are controlled by the mass fixer.
• Two Large Eddy Simulation (LES) protocols for modelling transport in plumes from emission hotspots have been delivered. The implementation of various configurations for the coupling of boundary conditions and various plume rise models have been completed with recommendations provided for the protocol.
• Test beds for parametrizations of convection and turbulent mixing have been designed focusing on the boundary layer and upper-troposphere and lower stratosphere. These use a comprehensive set of observations from field campaigns, very high-resolution LES simulations, as well as modelling protocols based on the CAMS IFS forecast and analysis of greenhouse gases and a new TransCom protocol for the evaluation of global atmospheric transport models. An initial evaluation of the IFS and ICON-ART simulations with the test beds has also been performed. The results show an overall good agreement with observations, but highlight sensitivities with model resolution and physical parametrizations which will be further investigated in the next half of the project using the Stochastic Perturbation of Parametrizations approach.
• A new protocol to evaluate global transport models has been designed for the TransCom model inter-comparison exercise to be led by the CATRINE project. It includes the four CATRINE global models (IFS, ICON-ART, LMDz, TM5), and 5 additional modelling groups outside CATRINE have also been invited after a successful TransCom international workshop organized by CATRINE. A preliminary evaluation of the CATRINE global model simulations shows the fit to the observations at background sites is generally good, although there are significant systematic differences in the inter-hemispheric gradient between the transport models, as well as a large spread near the surface and in the upper troposphere. New diagnostics are proposed to assess atmospheric transport processes based on vertically integrated mass fluxes which will help to elucidate the systematic errors and differences detected in the transport models during the TransCom intercomparison exercise. These diagnostics are commonly used in the evaluation of the hydrological cycle in Numerical Weather Prediction (NWP) re-analysis products and have the potential of improving atmospheric transport evaluation in inversion models.
