Evaluation of a 20-year simulation of nitrogen and sulfur deposition fluxes in IFS-COMPO

Within the Copernicus Atmosphere Monitoring Service (CAMS), ECMWF operates the Integrated Forecasting System with atmospheric composition extension (IFS-COMPO) to provide global forecasts and reanalyses of aerosols and trace gases. In support of ongoing preparations for a new CAMS reanalysis, which will cover the years 2003-present, multi-decadal model simulations with a fixed IFS-COMPO model configuration have been produced for the same period. The model version for these evaluations is similar as planned for the next CAMS Reanalysis. Particularly, the CAMS-GLOB-ANT-M01 ‘Mosaic’ anthropogenic emissions are used. But different than planned for the new CAMS reanalysis we exclude composition data assimilation and perform the simulation on a comparatively coarse model resolution (~80 km).

In this contribution we evaluate the quality of sulfur, oxidized nitrogen and reduced nitrogen deposition fluxes in IFS-COMPO for the period 2003-2022, making use of E4C as described in Williams et al., GMD, 18, 9913–9943 (2025). We present evaluations against various observational networks, namely CASTNet (US), EMEP (Europe) and EANET (Eastern Asia). Also we compare our simulation results with those obtained for the existing CAMS Reanalysis that is based on an older model configuration.

We will show to what extent the simulated deposition fluxes follow the observed trends in the different parts of the world, thereby giving confidence particularly in the used sulfur and nitrogen emissions on a continental scale. Uncertainties due to modelling will be highlighted by assessing our simulation results with multi-model assessments as done, e.g., in HTAP.