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| Titel |
Comparison of tropospheric chemistry schemes for use within global models |
| VerfasserIn |
K. M. Emmerson, M. J. Evans |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023285
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| Zusammenfassung |
| The changing concentraton of methane and ozone is one of the drivers for the changing
climate. Their concentration is largely controlled by the chemistry of the atmosphere. Within
chemistry-climate and transport models this chemistry is simplified for computational
expediency. In this work we compare the Master Chemical Mechanism (MCM) with six
tropospheric chemistry schemes (CRI-reduced, GEOSCHEM and a GEOS-CHEM adduct,
MOZART, TOMCAT and CBM-IV) that are used within composition transport models.
These tests occur within a box model framework under conditions derived from a
composition transport model and from field observations from a regional scale pollution
event. We find some significant variations between the chemical schemes. We conclude that
1) The inclusion of a gas phase N2O5+H2O reaction in some schemes and not others is a
large source of uncertainty in the inorganic chemistry. 2) There are significant variations in
the calculated concentration of PAN between the schemes, which will affect the
long range transport of reactive nitrogen in global models. 3) The representation
of isoprene chemistry differs hugely between the schemes, leading to significant
uncertainties on the impact of isoprene on composition. 4) Night-time chemistry
is badly represented with significant disagreements in the ratio of NO3 to NOx.
Resolving these four issues through further investigative laboratory studies will
reduce the uncertainties within the chemical schemes of global tropospheric models. |
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