 |
| Titel |
Single scattering by realistic, inhomogeneous mineral dust particles with stereogrammetric shapes |
| VerfasserIn |
H. Lindqvist, O. Jokinen, K. Kandler, D. Scheuvens, T. Nousiainen |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 1 ; Nr. 14, no. 1 (2014-01-06), S.143-157 |
| Datensatznummer |
250118248
|
| Publikation (Nr.) |
 copernicus.org/acp-14-143-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Light scattering by single, inhomogeneous mineral dust particles was
simulated based on shapes and compositions derived directly from measurements
of real dust particles instead of using a mathematical shape model. We
demonstrate the use of the stereogrammetric shape retrieval method in the context
of single-scattering modelling of mineral dust for four different dust types
– all of them inhomogeneous – ranging from compact, equidimensional shapes
to very elongated and aggregate shapes. The three-dimensional particle shapes
were derived from stereo pairs of scanning-electron microscope images, and
inhomogeneous composition was determined by mineralogical interpretation of
localized elemental information based on energy-dispersive spectroscopy.
Scattering computations were performed for particles of equal-volume
diameters, from 0.08 μm up to 2.8 μm at 550 nm wavelength, using the
discrete-dipole approximation. Particle-to-particle variation in scattering
by mineral dust was found to be quite considerable and was not well
reproduced by simplified shapes of homogeneous spheres, spheroids, or
Gaussian random spheres. Effective-medium approximation results revealed that
particle inhomogeneity should be accounted for even for small amounts of
absorbing media (here up to 2% of the volume), especially when considering
scattering by inhomogeneous particles at size parameters 3<x<8. When
integrated over a log-normal size distribution, the linear depolarization
ratio and single-scattering albedo were also found to be sensitive to
inhomogeneity. The methodology applied is work-intensive and the
light-scattering method used quite limited in terms of size parameter
coverage. It would therefore be desirable to find a sufficiently accurate but
simpler approach with fewer limitations for single-scattering modelling of
dust. For validation of such a method, the approach presented here could be
used for producing reference data when applied to a suitable set of target
particles. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|