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| Titel |
A new WRF-Chem treatment for studying regional-scale impacts of cloud processes on aerosol and trace gases in parameterized cumuli |
| VerfasserIn |
L. K. Berg, M. Shrivastava, R. C. Easter, J. D. Fast, E. G. Chapman, Y. Liu, R. A. Ferrare |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 2 ; Nr. 8, no. 2 (2015-02-24), S.409-429 |
| Datensatznummer |
250116116
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| Publikation (Nr.) |
 copernicus.org/gmd-8-409-2015.pdf |
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| Zusammenfassung |
| A new treatment of cloud effects on aerosol and trace gases within
parameterized shallow and deep convection, and aerosol effects on cloud
droplet number, has been implemented in the Weather Research and Forecasting
model coupled with Chemistry (WRF-Chem) version 3.2.1 that can be used to
better understand the aerosol life cycle over regional to synoptic scales.
The modifications to the model include treatment of the cloud droplet number
mixing ratio; key cloud microphysical and macrophysical parameters (including
the updraft fractional area, updraft and downdraft mass fluxes, and
entrainment) averaged over the population of shallow clouds, or a single deep
convective cloud; and vertical transport, activation/resuspension, aqueous
chemistry, and wet removal of aerosol and trace gases in warm clouds. These
changes have been implemented in both the WRF-Chem chemistry packages as well
as the Kain–Fritsch (KF) cumulus parameterization that has been modified to better
represent shallow convective clouds. Testing of the modified WRF-Chem has
been completed using observations from the Cumulus Humilis Aerosol Processing
Study (CHAPS). The simulation results are used to investigate the impact of
cloud–aerosol interactions on regional-scale transport of black carbon (BC),
organic aerosol (OA), and sulfate aerosol. Based on the simulations presented
here, changes in the column-integrated BC can be as large as −50% when
cloud–aerosol interactions are considered (due largely to wet removal), or
as large as +40% for sulfate under non-precipitating conditions due to
sulfate production in the parameterized clouds. The modifications to WRF-Chem
are found to account for changes in the cloud droplet number concentration
(CDNC) and changes in the chemical composition of cloud droplet residuals in
a way that is consistent with observations collected during CHAPS. Efforts
are currently underway to port the changes described here to the latest
version of WRF-Chem, and it is anticipated that they will be included in a
future public release of WRF-Chem. |
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