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| Titel |
Estimation of friction parameters in gravity currents by data assimilation in a model hierarchy |
| VerfasserIn |
A. Wirth |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 7, no. 2 ; Nr. 7, no. 2 (2011-04-15), S.245-255 |
| Datensatznummer |
250004538
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| Publikation (Nr.) |
 copernicus.org/os-7-245-2011.pdf |
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| Zusammenfassung |
This paper is the last in a series of three investigating the friction
laws and their parametrisation in idealised gravity currents in
a rotating frame. Results on the dynamics of a gravity current (Wirth, 2009) and on the estimation of
friction laws by data assimilation (Wirth and Verron, 2008) are combined to estimate the friction
parameters and discriminate between friction laws in non-hydrostatic
numerical simulations of gravity current dynamics, using data
assimilation and a reduced gravity shallow water model.
I demonstrate, that friction parameters and laws in gravity currents
can be estimated using data assimilation. The results clearly show
that friction follows a linear Rayleigh law for small Reynolds numbers
and the estimated value agrees well with the analytical value obtained
for non-accelerating Ekman layers. A significant and sudden departure
towards a quadratic drag law at an Ekman layer based Reynolds number
of around 800 is shown, in agreement with classical laboratory
experiments. The drag coefficient obtained compares well to friction
values over smooth surfaces. I show that data assimilation can be
used to determine friction parameters and discriminate between
friction laws and that it is a powerful tool in systematically
connecting models within a model hierarchy. |
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