Atmospheric Chemistry and Physics Discussions
www.atmos-chem-phys-discuss.net
1680-7367
1680-7375
6
2
2006
10.5194/acpd-6-2897-2006
http://www.atmos-chem-phys-discuss.net/6/2897/2006/
http://www.atmos-chem-phys-discuss.net/6/2897/2006/acpd-6-2897-2006.html
http://www.atmos-chem-phys-discuss.net/6/2897/2006/acpd-6-2897-2006.pdf
2897
2922
2006-04-11
Optical properties and mineralogical composition of different Saharan mineral dust samples: a laboratory study
C. Linke
O. Möhler
A. Veres
Á. Mohácsi
Z. Bozóki
G. Szabó
M. Schnaiter
Forschungszentrum Karlsruhe, Institute of Meteorology and Climate Research, P.O. Box 3640, 76021 Karlsruhe, Germany
University of Szeged, Faculty of Natural Sciences, Department of Optics and Quantum Electronics, P.O. Box 406, 6701 Szeged, Hungary
Research Group on Laser Physics of the Hungarian Academy of Sciences, Dóm tér 9., 6720 Szeged, Hungary
In aerosol chamber experiments optical properties of airborne mineral dust
samples of defined size distribution were measured. Extinction coefficients
(b<sub>ext</sub>) and mass specific extinction cross sections (σ<sub>ext</sub>)
were determined for Saharan dust samples from different locations. The
results for σ<sub>ext</sub> were not very sensitive to the type of dust
and varied at λ=550 nm between 3.3±0.4 m<sup>2</sup> g<sup>−1</sup> and
3.7±0.4 m<sup>2</sup> g<sup>−1</sup>. The absorption coefficients (b<sub>abs</sub>) and
mass specific absorption cross sections (σ<sub>abs</sub>) were
determined with a novel multi-wavelength photo-acoustic absorption
spectrometer (PAS). Between λ=266 nm and λ=1064 nm the
derived single scattering albedos (SSA) ranged from 0.63±0.04 to
0.99±0.01. Additionally the chemical and mineralogical composition of
the dust samples was analysed with special regard to the iron oxide phases
hematite and goethite. At λ=266 nm the mineral dust sample without
any detectable iron oxides showed a significantly higher SSA compared to the
sample with a hematite content of 0.6 wt-%.