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| Titel |
Using WRF-Chem to investigate the impact of night time nitrate radical chemistry and N2O5 heterogeneous chemistry on the chemical composition of the UK troposphere. |
| VerfasserIn |
S. Archer-Nicholls, D. Lowe, S. Utembe, G. McFiggans |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068729
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| Zusammenfassung |
| It is believed that NO3 is the primary oxidant at night time, significantly impacting
ozone formation, rain acidification and the formation and transformation of aerosols,
particularly through the formation of the ammonium nitrate particulate (Allan et. al.,
2000). However, many of the basic chemical processes controlling the formation and
removal of NO3, in particular, the N2O5 heterogeneous reactions, are often not
represented in models, although general parameterisations have been developed
(c.f. Bertram & Thornton, 2009). The ROle of Night time chemistry in controlling the
Oxidising Capacity of the atmOsphere (RONOCO) campaign is a project being funded
by NERC and being carried out by a collaboration of UK Universities. It aims to
better understand the role of the NO3 radical on the chemistry of the night time
atmosphere, its oxidation capacity and thus its overall effects on the composition of the
troposphere.
The Weather Research and Forecasting model with Chemistry (WRF-Chem) is a state of
the art regional climate model with fully coupled online air quality and meteorological
components allowing for better resolution of aerosol and gas-phase chemistry (Grell et. al.,
2005). It has been extended to include the Common Representative Intermediates
scheme (CRIv2-R5) (Watson et. al., 2008), a reduced chemical scheme designed to
simulate the atmospheric degradation of 220 species of hydrocarbons and VOCs. The
MOSAIC aerosol scheme (Zaveri et. al., 2008), has been extended to include a
reduced complexity condensed organic phase consisting of 13 semi-volatile and
2 involatile species (Topping et. al., 2012), as well as the N2O5 heterogeneous
reaction scheme of Bertram & Thornton (2009). We aim to use WRF-Chem to
compare the oxidation capacity of nighttime NO3 chemistry with that of daytime OH
chemistry.
The model was run using two nested grids: a 15km resolution domain over western
Europe, containing a 5km resolution domain over the UK. The RONOCO campaign
consisted of two flight periods: one during July 2010; the other during January 2011. We have
run five model scenarios for both these periods: a base case, with standard emissions and
chemistry; two scenarios with standard chemistry, but with halved and doubled NOx
transport emissions respectively; and two scenarios with standard emissions, but one
without N2O5 heterogeneous chemistry, and the other with the Cl- reaction pathway
disabled.
We will present results from the application of WRF-Chem to model the regional
chemical composition of the atmosphere about the UK. Sensitivities to changing emission
profiles and the impact of N2O5 heterogeneous chemistry will be discussed. Preliminary
comparisons between model results and aircraft data will be shown. The strengths and
weaknesses of our modelling approach, in particular the gains and drawbacks of using a fully
coupled online model for use in this campaign, will be highlighted. The wider impacts of
the processes investigated on the regional climate and air quality will be further
discussed.
Allan, B., et. al. (2000); J. Geophys. Res., 105, doi: 10.1046/j.1365-2370.2000.00208.
Bertram, T. H., Thornton, J. A. (2009); Atmos. Chem. Phys., 9, 8351-8363, doi:
10.5194/acp-9-8351-2009
Grell, G., et. al. (2005); Atmos. Environ., 39, 6957- 6975. doi: 10.1016/j.atmosenv.2005.04.027
Topping, D., Lowe, D. & McFiggans, G. (2012); Geosci. Model Dev., 5, 1-13.
doi:10.5194/gmd-5-1-2012
Watson, L., et. al. (2008); Atmos. Environ., 42, 7196- 7204, doi:
10.1016/j.atmosenv.2008.07.034
Zaveri, R. A., et. al. (2008); J. Geophys. Res., 113, doi:10.1029/2007JD008782 |
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