Are contributions of emissions to ozone a matter of scale? – a study using MECO(n) (MESSy v2.50)

Abstract

Abstract. Anthropogenic and natural emissions influence the tropospheric ozone budget, thereby affecting air quality and climate. To study the influence of different emission sources on the ozone budget, often source apportionment studies with a tagged tracer approach are performed. Studies investigating air quality issues usually rely on regional models with a fine spatial resolution, while studies focusing on climate-related questions often use coarsely resolved global models. It is well known that simulated ozone mixing ratios depend on the resolution of the model and the resolution of the emission inventory. Whether the contributions simulated using source apportionment approaches also depend on the model resolution, however, is still unclear. Therefore, this study attempts for the first time to analyse the impact of the model, the model resolution, and the emission inventory resolution on simulated ozone contributions using a diagnostic tagging method. The differences in the ozone contributions caused by these factors are compared with differences that arise from the usage of different emission inventories. To do so, we apply the MECO(n) (MESSy-fied ECHAM and COSMO models nested n times) model system which couples online a global chemistry-climate model with a regional chemistry-climate model equipped with a tagging scheme for source apportionment. The results of the global model (at 300 km horizontal resolution) are compared with the results of the regional model at 50 km (Europe) and 12 km (Germany) resolutions. Besides model-specific differences and biases that are discussed in detail, our results have important implications for other modelling studies and modellers applying source apportionment methods. First, contributions from anthropogenic emissions averaged over the continental scale are quite robust with respect to the model, model resolution, and emission inventory resolution. Second, differences on the regional scale caused by different models and model resolutions can be quite large, and regional models are indispensable for source apportionment studies on the subcontinental scale. Third, contributions from stratospheric ozone transported to the surface differ strongly between the models, mainly caused by differences in the efficiency of the vertical mixing. As stratospheric ozone plays an important role for ground level ozone, but the models show large differences in the amount of downward transported ozone, source apportionment methods should account for this source explicitly to better understand inter-model differences.

Attributing ozone and its precursors to land transport emissions in Europe and Germany

“…The namelist setup used for the simulations is part of the Supplement. The model data used in this study are available under the following DOI: https://doi.org/10.5281/zenodo.3908469 (Mertens, 2020).…”

“…More details about the emission inventory are provided by Hendricks et al (2017). Further details about the preprocessing of the emissions is given in Appendix A of Mertens (2017).…”

Evaluation of the coupled high-resolution atmospheric chemistry model system MECO(n) using in situ and MAX-DOAS NO<sub>2</sub> measurements

“…industrial and urban clusters) and quantify their impacts on non-linear photochemical processes, e.g. ozone production (Vinken et al, 2014;Visser et al, 2019;Mertens et al, 2020a) as well as on heterogeneous processes, e.g. par-V. Kumar et al: Regional model evaluation using MAX-DOAS ticulate nitrate production (Chen et al, 2020).…”

“…isolated point sources, road networks and ship tracks) and facilitate understanding of sector-specific impacts on secondary pollution (e.g. ozone production) (Colette et al, 2014;Mertens et al, 2020a). However, comparison with in situ measurements showed that these gains could only be quantitatively determined up to a resolution of ∼ 7 × 7 km 2 , beyond which major improvements were not observed (Colette et al, 2014).…”

Cleaner Skies during the COVID-19 Lockdown

“…The aircraft measurements were combined with satellite data of tropospheric NO 2 column densities from the Global Ozone Monitoring Experiment 2 (GOME-2; Munro et al 2016) and Sentinel-5P/Tropospheric Monitoring Instrument (TROPOMI; Veefkind et al 2012), and with cloud data retrieved from the SEVIRI Imager on the Meteosat Second Generation (MSG) satellite, as well as the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) (Winker et al 2010). The measurements were also used to evaluate the global chemistry climate model EMAC (Jöckel et al 2010) and the global-regional chemistry-climate model MECO(n) (Kerkweg and Jöckel 2012a,b;Mertens et al 2016).…”