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| Titel |
Comparison of two different sea-salt aerosol schemes as implemented in air quality models applied to the Mediterranean Basin |
| VerfasserIn |
P. Jiménez-Guerrero, O. Jorba, M. T. Pay, J. P. Montávez, S. Jerez, J. J. Gómez-Navarro, J. M. Baldasano |
| 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. 10 ; Nr. 11, no. 10 (2011-05-24), S.4833-4850 |
| Datensatznummer |
250009759
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| Publikation (Nr.) |
 copernicus.org/acp-11-4833-2011.pdf |
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| Zusammenfassung |
| A number of attempts have been made to incorporate sea-salt aerosol
(SSA) source functions in chemistry transport models with varying
results according to the complexity of the scheme considered. This
contribution compares the inclusion of two different SSA algorithms in
two chemistry transport models: CMAQ and CHIMERE. The main goal is to
examine the differences in average SSA mass and composition and to
study the seasonality of the prediction of SSA when applied to the
Mediterranean area with high resolution for a reference year. Dry and
wet deposition schemes are also analyzed to better understand the
differences observed between both models in the target area. The
applied emission algorithm in CHIMERE uses a semi-empirical
formulation which obtains the surface emission rate of SSA as
a function of the particle size and the surface wind speed raised to the power 3.41. The
emission parameterization included within CMAQ is somehow more
sophisticated, since fluxes of SSA are corrected with relative
humidity. In order to evaluate their strengths and weaknesses, the
participating algorithms as implemented in the chemistry transport
models were evaluated against AOD measurements from Aeronet and
available surface measurements in Southern Europe and the
Mediterranean area, showing biases around −0.002 and
−1.2 μg m−3, respectively. The results indicate
that both models represent accurately the patterns and dynamics of SSA
and its non-uniform behavior in the Mediterranean basin, showing
a strong seasonality. The levels of SSA strongly vary across the
Western and the Eastern Mediterranean, reproducing CHIMERE higher
annual levels in the Aegean Sea (12 μg m−3) and
CMAQ in the Gulf of Lion (9 μg m−3). The large
difference found for the ratio PM2.5/total SSA in CMAQ and
CHIMERE is also investigated. The dry and wet removal rates are very
similar for both models despite the different schemes implemented. Dry
deposition essentially follows the surface drag stress patterns,
meanwhile wet deposition is more scattered over the continent. CMAQ
tends to provide larger amounts of SSA dry deposition over the
Northern Mediterranean (0.7–1.0 g m−2 yr−1), meanwhile
the Southeastern Mediterranean accounts for the maximum annual dry
deposition in the CHIMERE model
(0.9–1.5 g m−2 yr−1). The wet deposition is dominated
by the accumulation mode and is strongly correlated to the
precipitation patterns, showing CMAQ a higher wet deposition/total
deposition ratio over coastal mountain chains. The results of both
models constitute a step towards increasing the understanding of the
SSA dynamics in a complex area as the Mediterranean. |
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