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| Titel |
The influence of fine ash on the dispersal of a volcanic cloud |
| VerfasserIn |
U. Niemeier, C. Timmreck, J. S. Rast, H. F. Graf, S. Kinne |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025152
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| Zusammenfassung |
| Volcanic eruptions exert a strong forcing on the Earth System caused by the emissions of ash
and SO2. The life time of the emitted volcanic aerosol varies between a few weeks for fine
ash and several years for sulfate in the stratosphere, causing strong radiative effects with
consequences for atmospheric processes.
While several model studies concerning volcanic sulfate aerosol exist, not much is known
about the impact of fine volcanic ash on atmospheric dynamics and composition. To study the
influence of the fine ash on the transport, dispersion and evolution of the volcanic aerosol
cloud, interactive simulations of a volcanic eruption in a global climate model are performed
with the middle atmosphere general circulation model MAECHAM5 including the
global aerosol module HAM. HAM calculates the aerosol microphysics of sulfate
and other species and their source and sink processes. In addition a fine volcanic
ash module for MAECHAM5 has been developed, which contains the emission
of volcanic ash, transport, sedimentation and deposition of the ash and its impact
on radiative processes. The ash size distribution is described with one log-normal
distribution.
Model studies have been performed for two different volcanos in the tropics and high
northern latitudes. Due to different meteorological conditions, the impact of the ash cloud on
dispersion and radiation is quite different. |
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