Wind-induced variability in the Northern Current (northwestern Mediterranean Sea) as depicted by a multi-platform observing system - Archive ouverte HAL Access content directly
Journal Articles OCEAN SCIENCE Year : 2018

Wind-induced variability in the Northern Current (northwestern Mediterranean Sea) as depicted by a multi-platform observing system

, (1) , , , (1) , , , , , , , (1) , (1) , (1)
1
Maristella Berta
  • Function : Author
Annalisa Griffa
  • Function : Author
Marcello G. Magaldi
  • Function : Author
Carlo Mantovani
  • Function : Author
Gian Pietro Gasparini
  • Function : Author
Julien Marmain
  • Function : Author
Anna Vetrano
  • Function : Author
Laurent Béguery
  • Function : Author
Mireno Borghini
  • Function : Author

Abstract

The variability and evolution of the Northern Current (NC) in the area off Toulon is studied for 2 weeks in December 2011 using data from a glider, a high-frequency (HF) radar network, vessel surveys, a weather station, and an atmospheric model. The NC variability is dominated by a synoptic response to wind events, even though the dataset also evidences early stages of transition 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 with 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 ageostrophic components of the surface currents, the wind-driven ageostrophic component is found to rotate by ≈ -25 to -30° to the right of the wind. The ageostrophic component magnitude corresponds to ≈2 % of the wind speed.
Fichier principal
Vignette du fichier
os-14-689-2018.pdf (2.89 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-03668088 , version 1 (14-05-2022)

Licence

Attribution - CC BY 4.0

Identifiers

Cite

Maristella Berta, Lucio Bellomo, Annalisa Griffa, Marcello G. Magaldi, Anne Molcard, et al.. Wind-induced variability in the Northern Current (northwestern Mediterranean Sea) as depicted by a multi-platform observing system. OCEAN SCIENCE, 2018, 14, pp.689-710. ⟨10.5194/os-14-689-2018⟩. ⟨insu-03668088⟩
63 View
5 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More