Sources of surface O; 3; in the UK: tagging O; 3; within WRF-Chem
Journal Article
Overview
abstract
; Tropospheric ozone (O; 3; ) concentrations depend on a combination of hemispheric, regional, and local-scale processes. Estimates of how much O; 3; is produced locally vs. transported from further afield are; essential in air quality management and regulatory policies. Here, a; tagged-ozone mechanism within the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is used to quantify the; contributions to surface O; 3; in the UK from anthropogenic nitrogen oxide (NO; ; x; ; ) emissions from inside and outside the UK during May–August 2015. The; contribution of the different source regions to three regulatory O; 3; metrics is also examined. It is shown that model simulations predict the; concentration and spatial distribution of surface O; 3; with a domain-wide; mean bias of −3.7 ppbv. Anthropogenic NO; ; x; ; emissions from the UK and Europe; account for 13 % and 16 %, respectively, of the monthly mean surface; O; 3; in the UK, as the majority (71 %) of O; 3; originates from the; hemispheric background. Hemispheric O; 3; contributes the most to; concentrations in the north and the west of the UK with peaks in May,; whereas European and UK contributions are most significant in the east,; south-east, and London, i.e. the UK's most populated areas, intensifying; towards June and July. Moreover, O; 3; from European sources is generally; transported to the UK rather than produced in situ. It is demonstrated that; more stringent emission controls over continental Europe, particularly in; western Europe, would be necessary to improve the health-related metric MDA8; O; 3; above 50 and 60 ppbv. Emission controls over larger areas, such as; the Northern Hemisphere, are instead required to lessen the impacts on; ecosystems as quantified by the AOT40 metric.;
