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| Titel |
The impact of speciated VOCs on regional ozone increment derived from measurements at the UK EMEP supersites between 1999 and 2012 |
| VerfasserIn |
C. S. Malley, C. F. Braban, P. Dumitrean, J. N. Cape, M. R. Heal |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 14 ; Nr. 15, no. 14 (2015-07-28), S.8361-8380 |
| Datensatznummer |
250119931
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| Publikation (Nr.) |
 copernicus.org/acp-15-8361-2015.pdf |
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| Zusammenfassung |
The impact of 27 volatile organic compounds (VOCs) on the regional O3
increment was investigated using measurements made at the UK EMEP supersites
Harwell (1999–2001 and 2010–2012) and Auchencorth (2012). Ozone at these
sites is representative of rural O3 in south-east England and northern
UK, respectively. The monthly-diurnal regional O3 increment was defined
as the difference between the regional and hemispheric background O3
concentrations, respectively, derived from oxidant vs. NOx correlation
plots, and cluster analysis of back trajectories arriving at Mace Head,
Ireland. At Harwell, which had substantially greater regional O3
increments than Auchencorth, variation in the regional
O3 increment mirrored
afternoon depletion of anthropogenic VOCs due to photochemistry (after
accounting for diurnal changes in boundary layer mixing depth, and weighting
VOC concentrations according to their photochemical ozone creation
potential). A positive regional O3 increment occurred consistently
during the summer, during which time afternoon photochemical depletion was
calculated for the majority of measured VOCs, and to the greatest extent for
ethene and m+p-xylene. This indicates that, of the measured VOCs, ethene
and m+p-xylene emissions reduction would be most effective in reducing the
regional O3 increment but that reductions in a larger number of VOCs
would be required for further improvement.
The VOC diurnal photochemical depletion was linked to anthropogenic sources
of the VOC emissions through the integration of gridded anthropogenic VOC
emission estimates over 96 h air-mass back trajectories. This
demonstrated that one factor limiting the effectiveness of VOC gridded
emissions for use in measurement and modelling studies is the highly
aggregated nature of the 11 SNAP (Selected Nomenclature for Air Pollution) source sectors in which they are reported,
as monthly variation in speciated VOC trajectory emissions did not reflect
monthly changes in individual VOC diurnal photochemical depletion.
Additionally, the major VOC emission source sectors during elevated regional
O3 increment at Harwell were more narrowly defined through
disaggregation of the SNAP emissions to 91 NFR (Nomenclature for Reporting) codes (i.e. sectors 3D2
(domestic solvent use), 3D3 (other product use) and 2D2 (food and drink)).
However, spatial variation in the contribution of NFR sectors to parent SNAP
emissions could only be accounted for at the country level. Hence, the
future reporting of gridded VOC emissions in source sectors more highly
disaggregated than currently (e.g. to NFR codes) would facilitate a more
precise identification of those VOC sources most important for mitigation of
the impact of VOCs on O3 formation.
In summary, this work presents a clear methodology for achieving a coherent
VOC, regional-O3-impact chemical climate using measurement data and
explores the effect of limited emission and measurement species on the
understanding of the regional VOC contribution to O3 concentrations. |
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