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Characterization of internal tide incoherence : Eulerian versus Lagrangian perspectives
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  • Zoé Caspar-Cohen,
  • Aurélien Ponte,
  • Noé Lahaye,
  • Xavier Carton,
  • Xiaolong Yu,
  • Sylvie Le Gentil
Zoé Caspar-Cohen
LOPS-Ifremer, LOPS-Ifremer

Corresponding Author:[email protected]

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Aurélien Ponte
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Noé Lahaye
Inria & IRMAR, campus universitaire de Beaulieu, Inria & IRMAR, campus universitaire de Beaulieu
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Xavier Carton
Université de Brest, Université de Brest
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Xiaolong Yu
Ifremer, Ifremer
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Sylvie Le Gentil
Ifremer, Ifremer
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The Lagrangian and Eulerian surface current signatures of a low-mode internal tide propagating through a turbulent balanced flow are compared in idealized numerical simulations. Lagrangian and Eulerian total (i.e. coherent plus incoherent) tidal amplitudes are found to be similar. Compared to Eulerian diagnostics, the Lagrangian tidal signal is more incoherent with comparable or smaller incoherence timescales and larger incoherent amplitudes. The larger level of incoherence in Lagrangian data is proposed to result from the deformation of Eulerian internal tide signal induced by drifter displacements. Based on the latter hypothesis, a theoretical model successfully predicts Lagrangian autocovariances by relating Lagrangian and Eulerian autocovariances and the properties of the internal tides and jet. These results have implications for the separation of balanced flow and internal tides signals in the sea level data collected by the future Surface Water and Ocean Topography (SWOT) satellite mission.
Jun 2022Published in Journal of Physical Oceanography volume 52 issue 6 on pages 1245-1259. 10.1175/JPO-D-21-0088.1