Surface currents in the Alderney Race from high-frequency radar measurements and three-dimensional modelling

Type Article
Date 2020-08
Language English
Author(s) Lopez G.1, Bennis Anne-Claire1, Barbin Y.2, Sentchev A.3, Benoit L.1, Marié Louis4
Affiliation(s) 1 : Morphodynamique Continentale et Côtière (M2C), CNRS UMR 6143, Univ. Caen Normandie, 14000 Caen, France
2 : Retired from Institut Méditerranéen d’Oceanologie (MIO), CNRS UMR 7294, IRD, Univ. Toulon, Univ. Aix-Marseille, 83041, Toulon, France
3 : Laboratory of Oceanology and Geosciences, University Littoral Côte d’Opale, Univ. Lille, CNRS UMR 8187 LOG, Wimereux 62930, France
4 : Laboratoire d’Océanographie Physique et Spatiale (LOPS), CNRS UMR 6523, Univ. Brest, Ifremer, IRD, 29280 Plouzané, France
Source Philosophical Transactions Of The Royal Society A-mathematical Physical And Engineering Sciences (1364-503X) (The Royal Society), 2020-08 , Vol. 378 , N. 2178 , P. 20190494 (20p.)
DOI 10.1098/rsta.2019.0494
WOS© Times Cited 4
Note This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.
Keyword(s) HF radar, surface current, Alderney Race, MARS 3D, WW3, high-frequency radar
Abstract

Two weeks of high-frequency radar measurements collected at the Alderney Race are compared with the results of a three-dimensional fully coupled wave–current model. Spatial current measurements are rare in this site, otherwise well investigated through modelling. Thus, the radar measurements offer a unique opportunity to examine the spatial reliability of numerical results, and can help to improve our understanding of the complex currents in the area. Comparison of observed and modelled surface current velocities showed a good agreement between the methods, represented by root mean squared errors ranging from 14 to 40 cm s−1 and from 18 to 60 cm s−1 during neap and spring tides, respectively. Maximum errors were found in shallow regions with consistently high current velocities, represented by mean neap and spring magnitudes of 1.25 m s−1 and 2.7 m s−1, respectively. Part of the differences between modelled and observed surface currents in these areas are thought to derive from limitations in the k-epsilon turbulence model used to simulate vertical mixing, when the horizontal turbulent transport is high. In addition, radar radial currents showed increased variance over the same regions, and might also be contributing to the discrepancies found. Correlation analyses yielded magnitudes above 0.95 over the entire study area, with better agreement during spring than during neap tides, probably because of an increase in the phase lag between radar and model velocities during the latter.

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Lopez G., Bennis Anne-Claire, Barbin Y., Sentchev A., Benoit L., Marié Louis (2020). Surface currents in the Alderney Race from high-frequency radar measurements and three-dimensional modelling. Philosophical Transactions Of The Royal Society A-mathematical Physical And Engineering Sciences, 378(2178), 20190494 (20p.). Publisher's official version : https://doi.org/10.1098/rsta.2019.0494 , Open Access version : https://archimer.ifremer.fr/doc/00643/75516/