Aviation-induced changes of atmospheric composition in the UTLS in the multi-scale Earth system model MECO(1)

<p>Aviation is concerned by its climate effects which results from CO₂ and non-CO₂ effects, comprising NO_x-induced changes of atmospheric ozone and methane. Here climate-chemistry models are required to advance our understanding on induced changes of reactive species and the associated radiative forcing associated to aviation emissions. Evaluation of such comprehensive models is key in order to be able to investigate associated uncertainties can use observational datasets from research infrastructures like IAGOS and DLR aircraft measurement campaign data.</p> <p>We use the MECO(n) system which is a &#8220;MESSy-&#64257;ed ECHAM and COSMO nested n-times&#8221;, relying on the Modular Earth Submodel System (MESSy) framework. For this purpose, both models have been equipped with the MESSy infrastructure, implying that the same process formulations (MESSy submodels) are available for both models. Modelled atmospheric distributions from the multi-scale model system MECO(n) are systematically compared to observational data from aircraft measurements in the upper troposphere and lower stratosphere. Nudging of meteorology to reanalysis data, and special diagnostics available within the modular MESSy infrastructure are implemented in the numerical simulations. Online sampling along aircraft trajectories allows to extract model data with a high temporal resolution (MESSy submodel S4D), in order to evaluate model representation and key processes. Beyond systematic evaluation with IAGOS scheduled aircraft measurements, particular focus on those episodes where dedicated measurements from aircraft campaigns are available. We present an analysis of reactive species, NO_y and ozone, which also identifies those weather pattern and synoptic situations where aviation contributes strong signals. We evaluate model representation of the NO_x-induces effect on radiatively active species ozone and hydroxyl radical in both model instances, ECHAM5 and COSMO. This is key for advancing the scientific understanding of NO_x-induced effects from aviation non-CO₂ effects required in order to quantify potential compensation and trade-offs and eventually in order to identify robust mitigation options for sustainable aviation.</p> <p>This project has received funding from the European Union&#8217;s Horizon 2020 research and innovation programme under grant agreement No 875036 (ACACIA, Advancing the Science for Aviation and Climate) and has been supported by the DLR-Projekt Eco2Fly. This work uses measurement data from the European Research Infrastructure CARIBIC/IAGOS. High-Performance Super Computing simulations have been performed by the Deutsches Klima-Rechenzentrum (DKRZ, Hamburg) and the Leibniz-Rechenzentrum (LRZ, M&#252;nchen).</p>