THE SANTANDER ATLANTIC TIME-SERIES A deep water observatory representative of the Eastern North Atlanctic.

Alicia Lavin1, Raquel Somavilla2, Cesar González-Pola3, Carmen Rodriguez Sra4, Elena Tel Dr4, Daniel Cano5, Amaia Viloria5, Elena Marcos5, Rocío Graña6 and Ignacio Reguera4, (1)Spanish Institute of Oceanography, IEO, Centro Oceanográfico de Santander, Santander, Spain, (2)Spanish Institute of Oceanography (IEO, CSIC), Physical Oceanography, Santander, Spain, (3)Spanish Institute of Oceanography, Physical Oceanography, Gijon, Spain, (4)IEO, Spain, (5)Spanish Institute of Oceanography (IEO, CSIC), Santander, Spain, (6)Spanish Institute of Oceanography-CSIC, Gijón, Spain
Abstract:
In 1886, Don Augusto González de Linares founded the Santander Biological station, one of the first marine biology stations around the world. Santander was the ideal environment because it provided very easy access to the study of deep sea species. Just a few dozen kilometers away from the coast, the seabed is already 3,000 m deep. 134 years later, this fact still makes Santander a privileged site for ocean research.

In order to reinforce its contribution to the global ocean observing system, the Spanish Institute of Oceanography (IEO) deployed in June 2007 an oceanic-meteorological buoy (AGL Buoy) in the southern Bay of Biscay, whose mooring position at 2800 m depth was chosen to coincide with the position of a standard section- the Santander standard section- running since 1991 by the IEO.

Thus, the Santander-Atlantic-Time-Series (SATS) including the AGL buoy data and its oceanographic station have provided -for more than 12 years now- repeated high-frequency observations of interlinked meteorological, oceanographic and biogeochemical variables that enable to obtain a comprehensive description of ocean processes from the seafloor to the atmosphere at a site representative of the mid-latitudes of the Eastern North Atlantic.

In the mid-2000s, extraordinary convective mixing events transformed ENA modal waters into a much saltier, warmer, and denser variety, transferring upper ocean heat and salt gained slowly over time to deeper layers. Increasing densities altered the ocean circulation patterns reversing the southward regional flow and enhancing the access of saltier southern waters to higher latitudes. Since the mid-2010s, saltening trends reversed. Annually averaged, the freshening is accompanied by above average temperatures, but persistent cold outbreaks at the end of the winter are enabling to develop very deep winter mixed layers in this new regime too. New ENA modal waters are warmer and remarkably fresher. The implications for North Atlantic circulation are still not known.

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