 |
| Titel |
Radical chemistry at night: comparisons between observed and modelled HOx, NO3 and N2O5 during the RONOCO project |
| VerfasserIn |
D. Stone, M. J. Evans, H. Walker, T. Ingham, S. Vaughan, B. Ouyang, O. J. Kennedy, M. W. McLeod, R. L. Jones, J. Hopkins, S. Punjabi, R. Lidster, J. F. Hamilton, J. D. Lee, A. C. Lewis, L. J. Carpenter, G. Förster, D. E. Oram, C. E. Reeves, S. Bauguitte, W. Morgan, H. Coe, E. Aruffo, C. Dari-Salisburgo, F. Giammaria, P. Carlo, D. E. Heard |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 3 ; Nr. 14, no. 3 (2014-02-05), S.1299-1321 |
| Datensatznummer |
250118353
|
| Publikation (Nr.) |
 copernicus.org/acp-14-1299-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| The RONOCO (ROle of Nighttime chemistry in controlling the Oxidising Capacity of the
AtmOsphere) aircraft campaign during July 2010 and January 2011 made
observations of OH, HO2, NO3, N2O5 and a number of
supporting measurements at night over the UK, and reflects the first
simultaneous airborne measurements of these species. We compare the observed
concentrations of these short-lived species with those calculated by a box
model constrained by the concentrations of the longer lived species using a
detailed chemical scheme. OH concentrations were below the limit of
detection, consistent with model predictions. The model systematically
underpredicts HO2 by ~200% and overpredicts NO3
and N2O5 by around 80 and 50%, respectively.
Cycling between NO3 and N2O5 is fast and thus we define the
NO3x (NO3x=NO3+N2O5) family. Production
of NO3x is overwhelmingly dominated by the reaction of NO2 with
O3, whereas its loss is dominated by aerosol uptake of N2O5,
with NO3+VOCs (volatile organic compounds) and NO3+RO2 playing smaller roles. The production of HOx and ROx radicals is mainly due to the
reaction of NO3 with VOCs. The loss of these radicals occurs through a
combination of HO2+RO2 reactions, heterogeneous processes and
production of HNO3 from OH+NO2, with radical propagation
primarily achieved through reactions of NO3 with peroxy radicals. Thus
NO3 at night plays a similar role to both OH and NO during the day in
that it both initiates ROx radical production and acts to propagate the
tropospheric oxidation chain. Model sensitivity to the N2O5
aerosol uptake coefficient (γN2O5) is discussed and we find
that a value of γN2O5=0.05 improves model simulations for
NO3 and N2O5, but that these improvements are at the expense
of model success for HO2. Improvements to model simulations for
HO2, NO3 and N2O5 can be realised simultaneously on
inclusion of additional unsaturated volatile organic compounds, however the
nature of these compounds is extremely uncertain. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|