Intense warm and saline upper ocean inflow in the southern Bay of Biscay in autumn–winter 2006–2007

• Published in: Continental Shelf Research
• Main Authors: Le Cann, Bernard, Serpette, Alain
• Other Authors: Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Centre Militaire d'Océanographie, EPSHOM
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: Slope and shelf currents; Wind forcing; Eastern boundary currents; Climate and interannual variability Hydrography; Bay of Biscay (NortheasternAtlantic); [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Northeast Atlantic
• Online Access: https://hal.science/hal-00385168; https://doi.org/10.1016/j.csr.2008.11.015

International audience Unusually warm and saline near-surface inflow was observed in the southern Bay of Biscay (Northeast Atlantic) in autumn–winter 2006–2007. These anomalies were swiftly entraine deast ward through the Iberian Poleward Current flowing over the slope and shelf. Here, we present a quasi-synoptic three dimensional view of this event, which started as early as August 2006. In situ hydrological and Lagrangian measurements were used to describe its characteristics. The warm anomaly was surface intensified over the shelf, with surface temperature above 17 °C, a monthly anomaly over 1 °C compared to the 1994–2006 period. The saline anomaly was maximum around 100–200 m deep, over the upper slope with values above 35.9 psu. Slope and shelf were seen to exhibit a complex structure of eastward (poleward) and westward (equatorward) currents. Maximum currents, observed near surface, over the upper slope in the eastern part of the Bay of Biscay, were determined to exceed 1.3 m s-1. This current system eventually became unstable, thereby promoting strong exchange of properties between coastal and deep ocean. The event was coincident with abnormal southerly wind conditions west of Iberia in autumn 2006, and with the unusually warm autumn–winter weather over western Europe. Adynamical analysis relying on wind forcing west and north of Iberia is proposed.