Assessment of the coastal dynamics in a nested zoom and feedback on the boundary current: the North-Western Mediterranean Sea case
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The Northern Current (hereafter NC), the major current in the North-Western Mediterranean (hereafter NWM) basin, has been largely investigated in the litterature for its mesoscale features. Its behaviour in the Var region can strongly condition the downstream flow along the Gulf of Lions shelf and Spain coast, making this zone a key area. However, the sub-mesoscale dynamics of the area and its potential impacts on the rest of the flow are not well known. This work reveals the potential interest of better simulating high-resolution dynamics in a restricted area and how this could improve the circulation representation in a larger area. To address this question, a very high resolution configuration (1/192∘) nested in an already existing high-resolution configuration (1/64∘) has been developed, using the NEMO model. Comparisons with observations show that the very high-resolution changes only weakly the mean NC characteristics but can significantly modify individual mesoscale events such as eddies and meanders occurring in the zoomed area. Furthermore, the coastal dynamics and episodic intrusions of a NC secondary branch inside a semi-enclosed bay appear to be significantly enhanced. In a second stage, the assessment of the feedback of this improved dynamics on the regional mesoscale dynamics is shown, this being allowed by the two-way coupling option of the embedded configuration using AGRIF.
KeywordsNorth-Western Mediterranean Sea Northern Current Mesoscale impact NEMO AGRIF nesting Two-way coupling
This study is a contribution to the MAREMED project, supported by LEFE-GMMC programme and to the CADOR project, financed by Toulon Provence Mediterranée. The calculations were performed using NEC-SX8 from GENCI-IDRIS resources (Grants 2015011707). Declerck A. PhD grants is supported by the French Ministry of Research. The authors acknowledge the MISTRALS/HyMeX, MERMeX and MOOSE database teams (ESPRI/IPSL and SEDOO/Observatoire Midi-Pyrénées) for their help in accessing the glider data and the Coriolis project and programmes that contribute to it (http://www.coriolis.eu.org) for having collected and made freely available the data. ADCP data are distributed by the French INSU within the SAVED project and SST product by the MyOcean project. The authors also wish to thank Mercator-Océan and Météo-France for providing numerical data and A. Petrenko for kindly providing the JULIO ADCP mooring data.
The authors wish to thank the two anonymous reviewers for their valuable comments and suggestions that greatly helped to improve the manuscript.
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