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| Titel |
Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud |
| VerfasserIn |
H. F. Dacre, A. L. M. Grant, B. T. Johnson |
| 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 ; 13, no. 3 ; Nr. 13, no. 3 (2013-02-01), S.1277-1291 |
| Datensatznummer |
250017629
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| Publikation (Nr.) |
 copernicus.org/acp-13-1277-2013.pdf |
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| Zusammenfassung |
| The Eyjafjallajökull volcano in Iceland emitted a cloud
of ash into the atmosphere during April and May 2010. Over the UK the ash
cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which
was equipped with in-situ probes measuring the concentration of volcanic ash
carried by particles of varying sizes. The UK Met Office Numerical
Atmospheric-dispersion Modelling Environment (NAME) has been used to simulate
the evolution of the ash cloud emitted by the Eyjafjallajökull volcano
during the period 4–18 May 2010. In the NAME simulations the processes
controlling the evolution of the concentration and particle size distribution
include sedimentation and deposition of particles, horizontal dispersion and
vertical wind shear. For travel times between 24 and 72 h, a 1/t
relationship describes the evolution of the concentration at the centre of
the ash cloud and the particle size distribution remains fairly constant.
Although NAME does not represent the effects of microphysical processes, it
can capture the observed decrease in concentration with travel time in this
period. This suggests that, for this eruption, microphysical processes play a
small role in determining the evolution of the distal ash cloud. Quantitative
comparison with observations shows that NAME can simulate the observed column-integrated mass if around 4% of the total emitted mass is assumed to be
transported as far as the UK by small particles (< 30 μm
diameter). NAME can also simulate the observed particle size distribution if
a distal particle size distribution that contains a large fraction of
< 10 μm diameter particles is used, consistent with the idea
that phraetomagmatic volcanoes, such as Eyjafjallajökull, emit very fine
particles. |
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