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| Titel |
Towards a Parameterization of Dust Devils for Weather and Climate models |
| VerfasserIn |
Bradley Jemmett-Smith, Peter Knippertz, John Marsham, Carl Gilkeson, Siegfried Raasch, Maren Weismuller, Fabian Hoffmann |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106516
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| Publikation (Nr.) |
 EGU/EGU2015-6191.pdf |
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| Zusammenfassung |
| Mineral dust is a key constituent in the climate system. Airborne mineral dust forms the
largest component of the global aerosol budget by mass and subsequently affects climate,
weather and biogeochemical processes. There remains large uncertainty in the quantitative
estimates of the dust cycle.
Dry-convective-vortices and non-rotating plumes of high winds (dust devils and dusty
plumes) serve as effective mechanisms for dust uplift. These micro-scale boundary-layer
phenomena occur over length scales of several hundred metres or less and are therefore
unresolved by current weather and climate models. Their short lifetime and small scale make
dust devils and dusty plumes difficult to observe routinely. Subsequently their contribution to
the global dust cycle is highly uncertain.
One key contributing factor to this uncertainty is the lack of knowledge regarding the
behaviour of dry-convective-vortices under different meteorological conditions and their
subsequent impact on dust uplift. Limited observations from field campaigns provide some
useful information, but recently our modelling capabilities have increased to a point, where
realistic model simulations of dust devils and dusty plumes can be run on a relatively large
domain to investigate this problem much more systematically. Here we use data obtained
from world-leading high-resolution (2 m horizontal grid spacing over a 4 km2 domain) large
eddy model simulations of numerous dust devil-like vortices performed with the PALM
model.
By measuring the effects of dry-convective-vortices on horizontal wind speed
distributions, we show that dry-convective-vortices are the main source of dust uplifting
winds within the mesoscale domain (when no mean background wind is applied). We then
investigate the effects of different meteorological (background wind, surface heat flux) and
surface conditions (inhomogeneities) on dry-convective-vortices and the subsequent impacts
on horizontal wind speed distributions. These relationships will form the basis
to develop a dust devil parameterization for use in weather and climate models. |
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