Internal solitary waves on the NW African shelf: A heuristic approach to localize diapycnal mixing hotspots
Por:
Gentil M., Floc'h F., Meunier T., Ruiz-Angulo A., Roudaut G., Perrot Y., Lebourges-Dhaussy A.
Publicada:
1 ene 2021
Resumen:
Turbulent mixing on continental shelves plays roles in the structure and dynamics of marine ecosystems, nutrient cycling, primary production and dispersion of pollutants. Describing and understanding internal wave dynamics enables improved mapping of mixing over continental shelves, especially in complex environments where many processes may interact, such as in upwelling systems. This paper describes internal wave propagation and dissipation in the Moroccan upwelling system using a comprehensive set of hydrographic observations made during two in situ surveys. The acoustic backscatter of the echosounder is shown to be a rapid and convenient survey tool for detecting internal solitary waves (ISWs) on large spatial scales, through the high-frequency oscillation of the zooplankton layer during nighttime conditions. Along ISW trains, enhanced diapycnal mixing episodes are observed with increased dissipation coefficients in the thermocline (O(10-7 W kg-1)), associated with overturning up to 6 m. Mixing due to internal wave soliton packets shows large spatial and temporal variability, but contributes to the overall mixing processes and is responsible for large intermittent variations in the thermocline position. The joint use of a multifrequency echosounder and a current profiler ADCP allows mixing to be quantified (via the Richardson number) on large spatial scales. Validation and use of this method in other coastal regions could be useful to determine regional mixing parameterization in numerical models. © 2021 Elsevier Ltd
Filiaciones:
Gentil M.:
Univ Perpignan Via Domitia, Centre de Recherche et de Formation sur les Environnements Méditerranéens, UMR5110, 52 avenue Paul Alduy, Perpignan, F-66860, France
Univ Brest, CNRS, Géosciences Océan, UMR6538, Plouzané, F-29280, France
Floc'h F.:
Univ Brest, CNRS, Géosciences Océan, UMR6538, Plouzané, F-29280, France
Meunier T.:
Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Ruiz-Angulo A.:
Institute of Earth Sciences, University of Iceland, 102 Reykjavik, Iceland
Roudaut G.:
Institut de la Recherche pour le Développement, Laboratoire de l'Environnement MArin - UMR LEMAR/IRD/UBO/CNRS/Ifremer, Plouzané, France
Perrot Y.:
Institut de la Recherche pour le Développement, Laboratoire de l'Environnement MArin - UMR LEMAR/IRD/UBO/CNRS/Ifremer, Plouzané, France
Lebourges-Dhaussy A.:
Institut de la Recherche pour le Développement, Laboratoire de l'Environnement MArin - UMR LEMAR/IRD/UBO/CNRS/Ifremer, Plouzané, France
Bronze
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