Regional modeling of internal-tide dynamics around New Caledonia – Part 1: Coherent internal-tide characteristics and sea surface height signature

Type Article
Date 2023-08-29
Language English
Author(s) Bendinger ArneORCID1, Cravatte SophieORCID1, 2, Gourdeau Lionel1, Brodeau Laurent3, Albert Aurélie3, Tchilibou Michel1, Lyard Florent1, Vic ClementORCID4
Affiliation(s) 1 : Université de Toulouse, LEGOS (CNES/CNRS/IRD/UPS), Toulouse, France
2 : IRD, Centre IRD de Nouméa, New Caledonia
3 : Université Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, Institut des Géosciences de l’Environnement, Grenoble, France
4 : Laboratoire d’Océanographie Physique et Spatiale, Univ. Brest, CNRS, Ifremer, IRD, Plouzané, France
Source Ocean Science (1812-0792) (Copernicus GmbH), 2023-08-29 , Vol. 19 , N. 4 , P. 1315-1338
DOI 10.5194/os-19-1315-2023

The southwestern tropical Pacific exhibits a complex bathymetry and represents a hot spot of internal-tide generation. Based on a tailored high-resolution regional model, we investigate for the first time the internal-tide field around the New Caledonia islands through energy budgets that quantify the coherent internal-tide generation, propagation, and dissipation. A total of 15.27 GW is converted from the barotropic to the baroclinic M2 tide with the main conversion sites associated with the most prominent bathymetric structures such as continental slopes and narrow passages in the north (2.17 GW) and ridges and seamounts south of New Caledonia (3.92 GW). The bulk of baroclinic energy is generated in shallow waters around 500 m depth and on critical to supercritical slopes, highlighting the limitations of linear semi-analytical models in those areas. Despite the strongly dominant mode-1 generation, more than 50 % of the locally generated energy either dissipates in the near field close to the generation sites or loses coherence. The remaining baroclinic energy propagates within well-defined tidal beams with baroclinic energy fluxes of up to 30 kW m−1 toward the open ocean. The New Caledonia site represents a challenge for SWOT (Surface Water and Ocean Topography) observability of balanced motion in the presence of internal tides with sea surface height (SSH) signatures >6 cm at similar wavelengths. We show for our study region that a correction of SSH for the coherent internal tide potentially increases the observability of balanced motion from wavelengths >160 km to well below 100 km.

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Bendinger Arne, Cravatte Sophie, Gourdeau Lionel, Brodeau Laurent, Albert Aurélie, Tchilibou Michel, Lyard Florent, Vic Clement (2023). Regional modeling of internal-tide dynamics around New Caledonia – Part 1: Coherent internal-tide characteristics and sea surface height signature. Ocean Science, 19(4), 1315-1338. Publisher's official version : , Open Access version :