Surface water circulation patterns in the southeastern bay of biscay: new evidences from hf radar data

Type Article
Date 2014-02
Language English
Author(s) Solabarrieta Lohitzune1, Rubio Anna1, Castanedo Sonia2, Medina Raul2, Charria GuillaumeORCID3, Hernandez Carl1
Affiliation(s) 1 : AZTI Tecnalia, Pasaia 20110, Gipuzkoa, Spain.
2 : Inst Hidraul Ambiental IH Cantabria, Santander 39011, Spain.
3 : IFREMER, DYNECO Lab Phys Hydrodynam & Sedimentaire, F-29280 Plouzane, France.
Source Continental Shelf Research (0278-4343) (Pergamon-elsevier Science Ltd), 2014-02 , Vol. 74 , P. 60-76
DOI 10.1016/j.csr.2013.11.022
WOS© Times Cited 41
Keyword(s) HF radar, Surface circulation patterns, Seasonal and mesoscale variability, Inertial currents, Bay of Biscay, Iberian Poleward Current (IPC)
Abstract High Frequency (HF) radar stations have been working operationally in the southeastern part of the Bay of Biscay since 2009. The (2) systems provide hourly surface currents, with 5 km spatial resolution and a radial coverage lying close to 180 km. The detailed and quantitative description of the spatial patterns observed by the HF radar offers new evidence on the main ocean processes, at different time scales, affecting a study area where surface currents show marked temporal and spatial variability. A clear seasonality in terms of sea surface currents and along-slope circulation is observed, with cyclonic and anticyclonic patterns during the winter and summer months, respectively. From the analysis of low-pass filtered currents, a key component of this seasonal variability is associated with the surface signature of the slope current (Iberian Poleward Current (IPC)). Clearly intensified over the upper part of the slope, this current circulates eastward off the Spanish coast and northward over the French shelves in winter.

Examination of the HF radar current fields reveals the presence of mesoscale structures over the area. At higher frequencies, an EOF (Empirical Orthogonal Function) analysis of the inertial band-pass filtered data is used to study the complex spatial and temporal patterns associated with these processes and to evaluate quantitatively the relative contribution of the high frequency to the total variability, in space and time. Overall, inertial currents represent between 10 and 40% of the total variability; their contribution is significantly greater in summer and over the deeper part of the slope. Tides contribute much less than the total Kinetic Energy (KE), although their contribution over the shelf can be higher than that of the inertial oscillations, during winter.
Full Text
File Pages Size Access
Author's final draft 52 596 KB Open access
17 7 MB Access on demand
Top of the page