Abstract
Abstract. A representation of atmospheric chemistry has been included in the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). The new chemistry modules complement the aerosol modules of the IFS for atmospheric composition, which is named C-IFS. C-IFS for chemistry supersedes a coupled system in which chemical transport model (CTM) Model for OZone and Related chemical Tracers 3 was two-way coupled to the IFS (IFS-MOZART). This paper contains a description of the new on-line implementation, an evaluation with observations and a comparison of the performance of C-IFS with MOZART and with a re-analysis of atmospheric composition produced by IFS-MOZART within the Monitoring Atmospheric Composition and Climate (MACC) project. The chemical mechanism of C-IFS is an extended version of the Carbon Bond 2005 (CB05) chemical mechanism as implemented in CTM Transport Model 5 (TM5). CB05 describes tropospheric chemistry with 54 species and 126 reactions. Wet deposition and lightning nitrogen monoxide (NO) emissions are modelled in C-IFS using the detailed input of the IFS physics package. A 1 year simulation by C-IFS, MOZART and the MACC re-analysis is evaluated against ozonesondes, carbon monoxide (CO) aircraft profiles, European surface observations of ozone (O3), CO, sulfur dioxide (SO2) and nitrogen dioxide (NO2) as well as satellite retrievals of CO, tropospheric NO2 and formaldehyde. Anthropogenic emissions from the MACC/CityZen (MACCity) inventory and biomass burning emissions from the Global Fire Assimilation System (GFAS) data set were used in the simulations by both C-IFS and MOZART. C-IFS (CB05) showed an improved performance with respect to MOZART for CO, upper tropospheric O3, and wintertime SO2, and was of a similar accuracy for other evaluated species. C-IFS (CB05) is about 10 times more computationally efficient than IFS-MOZART.
Highlights
Monitoring and forecasting of global atmospheric composition are key objectives of the atmosphere service of the European Copernicus programme
MOZ overestimates in winter and spring and this overestimation is more prominent in the UT, where MOZ is biased high throughout the year. This overestimation in UT is highest in spring, where it can be 25 % and more. These findings show that data assimilation in REAN improved UT O3 considerably but had only little influence in LT and MT
C-Integrated Forecasting System (IFS) benefits from the detailed cloud and precipitation physics of the IFS for the calculation of wet deposition and lightning nitrogen monoxide (NO) emission
Summary
Monitoring and forecasting of global atmospheric composition are key objectives of the atmosphere service of the European Copernicus programme. J. Flemming et al.: Tropospheric chemistry in the Integrated Forecasting System of ECMWF al., 2009) and greenhouse gases (Engelen et al, 2009) were integrated on-line in the IFS. Because of the complexity of the chemical mechanisms for reactive gases, modules for atmospheric chemistry were not initially included in the IFS. C-IFS is the global model system run in pre-operational mode as part of the Monitoring Atmospheric Composition and Climate – Interim Implementation project (MACC II and MACC III) in preparation of CAMS. Since C-IFS (CB05) replaced the current operational MACC model system for reactive gases (IFS-MOZART) both in data assimilation and forecast mode, the evaluation in this paper is carried out predominantly with observations that are used for the routine evaluation of the MACC II system.
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