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| Titel |
Testing the performance of state-of-the-art dust emission schemes using DO4Models field data |
| VerfasserIn |
K. Haustein, R. Washington, J. King, G. Wiggs, D. S. G. Thomas, F. D. Eckardt, R. G. Bryant, L. Menut |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 2 ; Nr. 8, no. 2 (2015-02-19), S.341-362 |
| Datensatznummer |
250116113
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| Publikation (Nr.) |
 copernicus.org/gmd-8-341-2015.pdf |
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| Zusammenfassung |
| Within the framework of the Dust Observations for Models (DO4Models) project,
the performance of three commonly used dust emission schemes is investigated
in this paper using a box model environment. We constrain the model with
field data (surface and dust particle properties as well as meteorological
parameters) obtained from a dry lake bed with a crusted surface in Botswana
during a 3 month period in 2011. Our box model results suggest that all
schemes fail to reproduce the observed horizontal dust flux. They
overestimate the magnitude of the flux by several orders of magnitude. The
discrepancy is much smaller for the vertical dust emission flux, albeit still
overestimated by up to an order of magnitude. The key parameter for this
mismatch is the surface crusting which limits the availability of erosive
material, even at higher wind speeds. The second-most important parameter is
the soil size distribution. Direct dust entrainment was inferred to be
important for several dust events, which explains the smaller gap between
modelled and measured vertical dust fluxes. We conclude that both features,
crusted surfaces and direct entrainment, need to be incorporated into dust
emission schemes in order to represent the entire spectra of source
processes. We also conclude that soil moisture exerts a key control on the
threshold shear velocity and hence the emission threshold of dust in the
model. In the field, the state of the crust is the controlling mechanism for
dust emission. Although the crust is related to the soil moisture content to
some extent, we are not as yet able to deduce a robust correlation between
state of crust and soil moisture. |
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