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| Titel |
Storm surge and wave simulations in the Gulf of Mexico using a consistent drag relation for atmospheric and storm surge models |
| VerfasserIn |
D. Vatvani, N. C. Zweers, M. Ormondt, A. J. Smale, H. Vries, V. K. Makin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 12, no. 7 ; Nr. 12, no. 7 (2012-07-27), S.2399-2410 |
| Datensatznummer |
250011000
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| Publikation (Nr.) |
 copernicus.org/nhess-12-2399-2012.pdf |
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| Zusammenfassung |
To simulate winds and water levels, numerical weather prediction (NWP) and
storm surge models generally use the traditional bulk relation for wind
stress, which is characterized by a wind drag coefficient. A still commonly
used drag coefficient in those models, some of them were developed in the
past, is based on a relation, according to which the magnitude of the
coefficient is either constant or increases monotonically with increasing
surface wind speed (Bender, 2007; Kim et al., 2008; Kohno and Higaki, 2006). The NWP and surge
models are often tuned independently from each other in order to obtain good
results. Observations have indicated that the magnitude of the drag
coefficient levels off at a wind speed of about 30 m s−1, and then decreases
with further increase of the wind speed. Above a wind speed of approximately
30 m s−1, the stress above the air-sea interface starts to saturate. To
represent the reducing and levelling off of the drag coefficient, the
original Charnock drag formulation has been extended with a correction term.
In line with the above, the Delft3D storm surge model is tested using both
Charnock's and improved Makin's wind drag parameterization to evaluate the
improvements on the storm surge model results, with and without inclusion of
the wave effects. The effect of waves on storm surge is included by
simultaneously simulating waves with the SWAN model on identical model grids
in a coupled mode. However, the results presented here will focus on the
storm surge results that include the wave effects.
The runs were carried out in the Gulf of Mexico for Katrina and Ivan
hurricane events. The storm surge model was initially forced with H*wind
data (Powell et al., 2010) to test the effect of the Makin's wind drag
parameterization on the storm surge model separately. The computed wind,
water levels and waves are subsequently compared with observation data.
Based on the good results obtained, we conclude that, for a good reproduction
of the storm surges under hurricane conditions, Makin's new drag
parameterization is favourable above the traditional Charnock relation.
Furthermore, we are encouraged by these results to continue the studies and
establish the effect of improved Makin's wind drag parameterization in the
wave model.
The results from this study will be used to evaluate the relevance of
extending the present towards implementation of a similar wind drag
parameterization in the SWAN wave model, in line with our aim to apply a
consistent wind drag formulation throughout the entire storm surge modelling
approach. |
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