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| Titel |
Microphysical simulations of new particle formation in the upper troposphere and lower stratosphere |
| VerfasserIn |
J. M. English, O. B. Toon, M. J. Mills, F. Yu |
| 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. 17 ; Nr. 11, no. 17 (2011-09-09), S.9303-9322 |
| Datensatznummer |
250010064
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| Publikation (Nr.) |
 copernicus.org/acp-11-9303-2011.pdf |
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| Zusammenfassung |
| Using a three-dimensional general circulation model with sulfur chemistry
and sectional aerosol microphysics (WACCM/CARMA), we studied aerosol
formation and microphysics in the upper troposphere and lower stratosphere
(UTLS) as well as the middle and upper stratosphere based on three
nucleation schemes (two binary homogeneous schemes and an ion-mediated
scheme related to one of the binary schemes). Simulations suggest that
ion-mediated nucleation rates in the UTLS are 25 % higher than its related
binary scheme, but that the rates predicted by the two binary schemes vary
by two orders of magnitude. None of the nucleation schemes is superior at
matching the limited observations available at the smallest sizes. However,
it is found that coagulation, not nucleation, controls number concentration
at sizes greater than approximately 10 nm. Therefore, based on this study,
processes relevant to atmospheric chemistry and radiative forcing in the
UTLS are not sensitive to the choice of nucleation schemes. The dominance of
coagulation over other microphysical processes in the UTLS is consistent
with other recent work using microphysical models. Simulations using all
three nucleation schemes compare reasonably well to observations of size
distributions, number concentration across latitude, and vertical profiles
of particle mixing ratio in the UTLS. Interestingly, we find that we need to
include Van der Waals forces in our coagulation scheme to match the UTLS
aerosol concentrations. We conclude that this model can reasonably represent
sulfate microphysical processes in the UTLS, and that the properties of
particles at atmospherically relevant sizes appear to be insensitive to the
details of the nucleation scheme. We also suggest that micrometeorites,
which are not included in this model, dominate the aerosol properties in the
upper stratosphere above about 30 km. |
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