Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/os-2018-20
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
01 Mar 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Ocean Science (OS).
Wind induced variability in the Northern Current (North-Western Mediterranean Sea) as depicted by a multi-platform observing system
Maristella Berta1, Lucio Bellomo2,3, Annalisa Griffa1,4, Marcello Magaldi1,5, Anne Molcard2,3, Carlo Mantovani1, Gian Pietro Gasparini1, Julien Marmain6, Anna Vetrano1, Laurent Béguery7, Mireno Borghini1, Yves Barbin8, Joel Gaggelli8, and Céline Quentin8 1CNR-ISMAR, Lerici, Italy
2MIO, Université de Toulon, CNRS, IRD, La Garde, France
3MIO, Aix-Marseille Université, CNRS, IRD, Marseille, France
4RSMAS, University of Miami, Miami, FL, USA
5Johns Hopkins University, Baltimore, MD, USA
6Degreane Horizon, Cuers, France
7ACSA, 9 Europarc, 13590 Meyreuil, France
8MIO, CNRS, Aix-Marseille Université, Université de Toulon, IRD, Marseille, France
Abstract. The variability and evolution of the Northern Current (NC) in the area off Toulon is studied for two weeks in December 2011 using data from a glider, a HF radar network, vessel surveys, a meteo station, and an atmospheric model. The NC variability is dominated by a synoptic response to wind events, even though a seasonal trend is also observed, transitioning from late summer to fall-winter conditions. With weak winds the current is mostly zonal and in geostrophic balance even at the surface, with a zonal transport associated to the NC of ≈ 1 Sv. Strong westerly wind events (longer than 2–3 days) induce an interplay between the direct wind induced ageostrophic response and the geostrophic component: upwelling is observed, with offshore surface transport, surface cooling, flattening of the isopycnals and reduced zonal geostrophic transport (0.5–0.7 Sv). The sea surface response to wind events, as observed by the HF radar, shows total currents rotated at ≈ −55° to −90° to the right of the wind. Performing a decomposition between geostrophic and geostrophic components of the surface currents, the wind driven ageostrophic component is found to rotate of ≈ −25° to −30° to the right of the wind. The ageostrophic component magnitude corresponds to ≈ 2 % of the wind speed.
Citation: Berta, M., Bellomo, L., Griffa, A., Magaldi, M., Molcard, A., Mantovani, C., Gasparini, G. P., Marmain, J., Vetrano, A., Béguery, L., Borghini, M., Barbin, Y., Gaggelli, J., and Quentin, C.: Wind induced variability in the Northern Current (North-Western Mediterranean Sea) as depicted by a multi-platform observing system, Ocean Sci. Discuss., https://doi.org/10.5194/os-2018-20, in review, 2018.
Maristella Berta et al.
Maristella Berta et al.
Maristella Berta et al.

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Short summary
The variability of the Northern Current (NC) in the NW Med Sea is studied using data from observations and models. The NC variability is dominated by a synoptic response to wind events, even though a seasonal trend is also observed. The combination of autonomous observing platforms with classical marine surveys provides high resolution datasets useful for specific scientific purposes but also for practical applications such as the management of marine shared resources in the Mediterranean Sea.
The variability of the Northern Current (NC) in the NW Med Sea is studied using data from...
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