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| Titel |
Feedbacks of dust and boundary layer meteorology during a dust storm in the eastern Mediterranean |
| VerfasserIn |
S. Remy, A. Benedetti, A. Bozzo, T. Haiden, L. Jones, M. Razinger, J. Flemming, R. J. Engelen, V. H. Peuch, J. N. Thepaut |
| 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 ; 15, no. 22 ; Nr. 15, no. 22 (2015-11-20), S.12909-12933 |
| Datensatznummer |
250120175
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| Publikation (Nr.) |
 copernicus.org/acp-15-12909-2015.pdf |
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| Zusammenfassung |
Aerosols affect the atmosphere through direct interaction with
short-wave and long-wave radiation and the microphysical properties of
clouds. In this paper we report in detail on several mechanisms by which the
short-term impact of dust on surface radiative fluxes can affect the dust
loading of the atmosphere via modification of boundary-layer meteorology.
This in turn affects the aerosol radiative forcing itself. Examples of these
feedbacks between dust and boundary layer meteorology were observed during a
series of dust storms in the Sahara and the eastern Mediterranean
in April 2012. These case studies have been analysed using the Monitoring
Atmospheric Composition and Climate – Interim Implementation (MACC-II)
system.
The radiative fluxes in the short-wave and long-wave spectra were both
significantly affected by the prognostic aerosol–radiation interaction,
which in turn impacted the meteorological simulation. Reduced incoming solar
radiation below the aerosol layers led to a decrease in maximum surface
temperatures and to a more stable thermal stratification of the lower
atmosphere. This in turn forced weaker surface wind speeds and eventually
smaller dust emissions. Moreover, we also observed a secondary impact of the
aerosol radiative forcing, whereby horizontal gradients of surface
temperature were increased at the edge of the dust plume, which led to local
increases of surface wind speeds due to the thermal wind effect. The
differentiated impact of the aerosol layer on surface pressure also
contributed to the increase in surface wind speed and dust production in the
same area.
Enhanced long-wave radiative fluxes by the dust mass were associated with
opposite processes. Less stable thermal stratification at night, brought
mainly by higher minimum temperatures at the surface, caused stronger surface
winds. At the edge of the dust storm, weaker horizontal temperature and
pressure gradients forced lower winds and reduced dust production.
Regarding dust emissions, short-wave radiative forcing had a larger
impact than long-wave radiative forcing, corroborating several previous studies. For
surface temperature, short-wave and long-wave contribution were close in
intensity.
These feedbacks were amplified when using data assimilation to build the
aerosol analysis of the MACC-II global system. This led to an improvement in
the short-term forecasts of thermal radiative fluxes and surface
temperatures. |
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