Tropospheric ozone in the UK: modelling its sources and the impact of European anthropogenic emissions

Romero Alvarez, Leidy (2019) Tropospheric ozone in the UK: modelling its sources and the impact of European anthropogenic emissions. Doctoral thesis, University of East Anglia.

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Ozone (O3) is a pollutant of concern for policy-makers because of its detrimental effects on human health, agriculture and ecosystems. Near the surface, O3 has an atmospheric lifetime of hours. However, once it is lifted to the free troposphere, O3 can live for several weeks and be transported over long distances, jeopardizing the compliance of air quality standards downwind. This thesis aims to further the understanding of the dependence of the UK on domestic and foreign emissions controls to meet local and European ozone air quality standards. Numerical simulations are carried out using WRF-Chem with a novel ozone-tagging method that has been implemented. Meteorology and two different chemical mechanisms, MOZART-4 and CRImech, were evaluated using surface observations acquired during the ICOZA field campaign of 2015.

Results confirm the prominent role of short-range transport of O3 from continental Europe to the UK as well as from no-controllable O3 sources such as the hemispheric ozone, which account for 71% of the total modelled O3 from May to August. The contribution of O3 from European NOx emissions is principally due to the transport of O3 rather than NOx reservoir.

It is shown that emission controls would be required in different source regions for compliance of ozone standards such as MDA8 O3 of 50 and 60 ppbv. For example, emissions controls in France affect mostly the south and southeast of the UK while domestic emissions controls are more relevant for the Midlands and the northern regions. By contrast, attainment of lower exposure thresholds, e.g., AOT40 metric, would primarily require the regulation of the hemispheric ozone levels.

O3 from Germany, the Benelux, France and ship emissions in the North Sea are responsible for the build-up of O3 in the southeast UK during the summertime 2015 pollution episode. Furthermore, process analysis diagnostics demonstrates that vertical mixing in the morning can bring O3 and precursors from the residual layer to the ground which contributes to the build-up of O3 during pollution episodes.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Chris White
Date Deposited: 17 Mar 2021 09:11
Last Modified: 17 Mar 2021 09:11


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