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| Titel |
Validation of numerical waves models in strong currents, a tribute to Owen Phillips. |
| VerfasserIn |
Fabrice Ardhuin, Aron Roland |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250049901
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| Zusammenfassung |
| Today's numerical wave models are least accurate in swell-dominated contitions and in coastal
environments, in particular in enclosed basins. Recent development have brought considerable
improvements in swell-dominated conditions thanks to a better understanding of swell energy
dissipation (Ardhuin et al. Geophys. Res. Lett. 2009) and work is ongoing to also correct
biases on the spatial distribution of swell fields (Delpey et al., J. Geophys. Res. 2010).
The coastal areas present several challenges in terms of forcing fields (winds and currents),
numerical constraints (high resolution needed at the shoreline) and still poorly represented physical
processes (wave breaking, bottom friction). Here we analyse in detail the behaviour of waves over strongly
varying current from the laboratory scale (Lai et al., J. Geophys. Res. 1989) to the coastal ocean, using
the best possible numerical schemes and
field observations from the French Atlantic coast with incoming significant wave heights up to 12~m
and tidal currents exceeding 3 m/s in some places. It is found that both the conservative
(refraction and 'bunching') and dissipative effects play an important role. As ancitipated by
Phillips (J. Phys. Oceanogr. 1984), a non-linear dissipation term can provide a good reproduction of
observed tidal-induced modulations of wave heights and periods, where more traditional forms (e.g. Bidlot
et al., Tech. Rep. 2005) suffer from unphysical steepness definitions.
We also find that the directional spreading of waves is systematically and strongly underestimated
in the presence of strong currents. We attribute this effect to a non-modeled scattering of waves. |
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