Signature of the coastal circulation variability in the altimetric data in the southern Bay of Biscay during winter and fall 2004

Gaëlle Herbert (1) , Nadia Ayoub (2) , Patrick Marsaleix (3) , Florent Lyard (2)

1 LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales
2 ECOLA - Echanges Côte-Large
3 LAERO - Laboratoire d'aérologie

The upper circulation in the southern Bay of Biscay is analysed over winter and fall 2004 using a coastal altimetric dataset, moorings, sea surface temperature (SST) observations and a regional simulation from the SYMPHONIE model. The aim is to determine whether altimetric data can detect occurrences of a slope current (the Iberian Poleward Current, IPC). We first analyse in situ and SST data. The results show pulses of a warm surface poleward flow (IPC) limited to the westernmost part of the northern Spanish coast. Along-track TOPEX/Poseidon and Jason-1 data are analysed over three 'events' (Jan., Feb., and Oct. 2004). Altimetric data can depict the main pulses. They provide some information on their spatial variability but the present in situ dataset is not dense enough to assess this information. Local inconsistencies between neighbouring tracks may be related to uncertainties in altimetric corrections. The simulated fields are consistent with the in situ observations. They allow us to better understand the IPC subsurface properties and its signature in altimetric data. The ability of altimetry to monitor IPC pulses under any atmospheric conditions or when the SST signature is weak makes it an essential component for the IPC observing system in addition to satellite SST and moorings data.

Mots clés: Symphonie numerical model; TOPEX/Poseidon and Jason-1 altimetry; Coastal ocean circulation; Iberian Poleward Current; Bay of Biscay

Domaines: Océanographie

Gaëlle Herbert, Nadia Ayoub, Patrick Marsaleix, Florent Lyard. Signature of the coastal circulation variability in the altimetric data in the southern Bay of Biscay during winter and fall 2004. Journal of Marine Systems, 2011, 88 (2), pp.139-158. ⟨10.1016/j.jmarsys.2011.03.004⟩. ⟨hal-00766461⟩