 |
| Titel |
Cloud processing of mineral dust: direct comparison of cloud residual and clear sky particles during AMMA aircraft campaign in summer 2006 |
| VerfasserIn |
A. Matsuki, A. Schwarzenboeck, H. Venzac, P. Laj, S. Crumeyrolle, L. Gomes |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 3 ; Nr. 10, no. 3 (2010-02-01), S.1057-1069 |
| Datensatznummer |
250008029
|
| Publikation (Nr.) |
 copernicus.org/acp-10-1057-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
In order to gain insights into the characteristics of the
mineral dust particles incorporated in the actual cloud droplets and the
related cloud processing, the French ATR-42 research aircraft equipped both
with a counterflow virtual impactor (CVI) and community aerosol inlet was
deployed in Niamey, Niger (13°30' N, 02°05' E) in August 2006 within
the framework of the African Monsoon Multidisciplinary Analysis (AMMA)
project.
Cloud residual and clear-sky particles were collected separately and
analyzed individually using a transmission electron microscope (TEM) and a
scanning electron microscope coupled with an energy dispersive X-ray
spectroscopy (SEM-EDX). The analysis revealed interesting characteristics on
the coarse dust particles (Dp>1μm), particularly those which
likely had acted as CCN.
Traces of heterogeneously formed secondary sulfate, chloride and nitrate
were found on many dust particles (though fraction of sulfate may be present
in the form of gypsum as primary dust component). These secondary species
were particularly enhanced in clouds (i.e. cloud processing). The study
illustrates that calcium-rich particles assumed to be carbonates (Calcite,
Dolomite) contained the secondary species in significantly larger frequency
and amount than the silicates (Quartz, Feldspar, Mica, Clay), suggesting
that they represent the most reactive fraction of the mineral dust. A
surprisingly large fraction of the Ca-rich particles were already found in
deliquesced form even in clear-sky conditions, most probably reflecting
their extreme hygroscopicity, resulting from their reaction with HNO3
gas.
Both silicate and Ca-rich particles were found dominant among the
supermicron cloud residues, and they were supposed to be those previously
activated as CCN. It is highly probable that the observed formation of
soluble materials enhanced their cloud nucleating abilities. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|