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| Titel |
Density currents as a desert dust mobilization mechanism |
| VerfasserIn |
S. Solomos, G. Kallos, E. Mavromatidis, J. Kushta |
| 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 ; 12, no. 22 ; Nr. 12, no. 22 (2012-11-27), S.11199-11211 |
| Datensatznummer |
250011624
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| Publikation (Nr.) |
 copernicus.org/acp-12-11199-2012.pdf |
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| Zusammenfassung |
| The formation and propagation of density currents are well
studied processes in fluid dynamics with many applications in other science
fields. In the atmosphere, density currents are usually meso-β/γ
phenomena and are often associated with storm downdrafts. These
storms are responsible for the formation of severe dust episodes (haboobs)
over desert areas. In the present study, the formation of a convective cool
pool and the associated dust mobilization are examined for a representative
event over the western part of Sahara desert. The physical processes
involved in the mobilization of dust are described with the use of the
integrated atmospheric-air quality RAMS/ICLAMS model. Dust is effectively
produced due to the development of near surface vortices and increased
turbulent mixing along the frontal line. Increased dust emissions and
recirculation of the elevated particles inside the head of the density
current result in the formation of a moving "dust wall". Transport of the
dust particles in higher layers – outside of the density current – occurs
mainly in three ways: (1) Uplifting of preexisting dust over the frontal line
with the aid of the strong updraft (2) Entrainment at the upper part of the
density current head due to turbulent mixing (3) Vertical mixing after the
dilution of the system. The role of the dust in the associated convective
cloud system was found to be limited. Proper representation of convective
processes and dust mobilization requires the use of high resolution (cloud
resolving) model configuration and online parameterization of dust
production. Haboob-type dust storms are effective dust sources and should be
treated accordingly in dust modeling applications. |
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