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| Titel |
Simulation of the diurnal variations of the oxygen isotope anomaly (Δ¹⁷O) of reactive atmospheric species |
| VerfasserIn |
S. Morin, R. Sander, J. Savarino |
| 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 ; 11, no. 8 ; Nr. 11, no. 8 (2011-04-19), S.3653-3671 |
| Datensatznummer |
250009640
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| Publikation (Nr.) |
 copernicus.org/acp-11-3653-2011.pdf |
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| Zusammenfassung |
The isotope anomaly (Δ17O) of secondary
atmospheric species such as nitrate (NO3−) or hydrogen
peroxide (H2O2) has potential to provide useful
constrains on their formation pathways. Indeed, the
Δ17O of their precursors (NOx,
HOx etc.) differs and depends on their interactions
with ozone, which is the main source of non-zero
Δ17O in the atmosphere. Interpreting variations
of Δ17O in secondary species requires an
in-depth understanding of the Δ17O of their
precursors taking into account non-linear chemical regimes
operating under various environmental settings.
This article reviews and illustrates a series of basic concepts relevant to the
propagation of the Δ17O of ozone to other reactive or secondary atmospheric species
within a photochemical box model. We present results from numerical simulations carried out
using the atmospheric chemistry box model CAABA/MECCA to explicitly compute the diurnal variations of the isotope
anomaly of short-lived species such as NOx and HOx. Using a
simplified but realistic tropospheric gas-phase chemistry mechanism,
Δ17O was propagated from ozone to
other species (NO, NO2, OH, HO2,
RO2, NO3, N2O5, HONO,
HNO3, HNO4, H2O2) according to the
mass-balance equations, through the implementation of
various sets of hypotheses pertaining to the transfer of
Δ17O during chemical reactions.
The model results confirm that diurnal variations in
Δ17O of NOx predicted by the
photochemical steady-state relationship during the day match
those from the explicit treatment, but not at night.
Indeed, the Δ17O of NOx is "frozen" at night
as soon as the photolytical lifetime of NOx drops
below ca. 10 min. We introduce and quantify the diurnally-integrated
isotopic signature (DIIS) of sources of atmospheric nitrate
and H2O2, which is of particular relevance to larger-scale
simulations of Δ17O where high
computational costs cannot be afforded. |
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