 |
| Titel |
Efficiency of the deposition mode ice nucleation on mineral dust particles |
| VerfasserIn |
O. Möhler, P. R. Field, P. Connolly, S. Benz, H. Saathoff, M. Schnaiter, R. Wagner, R. Cotton, M. Krämer, A. Mangold, A. J. Heymsfield |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 6, no. 10 ; Nr. 6, no. 10 (2006-07-21), S.3007-3021 |
| Datensatznummer |
250004012
|
| Publikation (Nr.) |
 copernicus.org/acp-6-3007-2006.pdf |
|
|
|
|
|
| Zusammenfassung |
| The deposition mode ice nucleation efficiency of various dust aerosols was
investigated at cirrus cloud temperatures between 196 and 223 K
using the aerosol and cloud chamber facility AIDA (Aerosol Interaction and
Dynamics in the Atmosphere). Arizona test dust (ATD) as a reference material
and two dust samples from the Takla Makan desert in Asia (AD1) and the Sahara
(SD2) were used for the experiments at simulated cloud conditions. The dust
particle sizes were almost lognormally distributed with mode diameters
between 0.3 and 0.5 μm and geometric standard deviations
between 1.6 and 1.9. Deposition ice nucleation was most efficient on ATD
particles with ice-active particle fractions of about 0.6 and 0.8 at an
ice saturation ratio Si<1.15 and temperatures of 223 and
209 K, respectively. No significant change of the ice nucleation
efficiency was found in up to three subsequent cycles of ice activation and
evaporation with the same ATD aerosol. This indicates that the phenomenon of
preactivation does not apply to ATD particles. The desert dust samples SD2
and AD1 showed a significantly lower fraction of active deposition nuclei,
about 0.25 at 223 K and Si<1.35. For all samples the ice
activated aerosol fraction could be approximated by an exponential equation
as function of Si. This indicates that deposition ice nucleation on
mineral particles may not be treated in the same stochastic sense as
homogeneous freezing. The suggested formulation of ice activation spectra may
be used to calculate the formation rate of ice crystals in models, if the
number concentration of dust particles is known. More experimental work is
needed to quantify the variability of the ice activation spectra as function
of the temperature and dust particle properties. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|