Daily scale wintertime sea surface temperature and IPC-Navidad variability in the southern Bay of Biscay from 1981 to 2010

Type Article
Date 2013
Language English
Author(s) Esnaola G.1, Saenz J.2, 3, Zorita E.4, Fontan A.1, Valencia V.1, Lazure PascalORCID5
Affiliation(s) 1 : AZTI Tecnalia, Div Marine Res, Pasaia 20110, Gipuzkoa, Spain.
2 : Univ Basque Country UPV EHU, Fac Sci & Technol, Dept Appl Phys 2, Leioa 48940, Spain.
3 : Res Ctr Expt Marine Biol & BioTechnol PIE UPV EHU, Plentzia 48620, Spain.
4 : Helmholtz Zentrum Geesthacht, Inst Coastal Res, D-21502 Geesthacht, Germany.
5 : IFREMER, Dept DYNECO, Ctr Brest, F-29280 Plouzane, France.
Source Ocean Science (1812-0784) (Copernicus Gesellschaft Mbh), 2013 , Vol. 9 , N. 4 , P. 655-679
DOI 10.5194/os-9-655-2013
WOS© Times Cited 7
Abstract The combination of remotely sensed gappy Sea surface temperature (SST) images with the missing data filling DINEOF (data interpolating empirical orthogonal functions) technique, followed by a principal component analysis of the reconstructed data, has been used to identify the time evolution and the daily scale variability of the wintertime surface signal of the Iberian Poleward Current (IPC), or Navidad, during the 1981-2010 period. An exhaustive comparison with the existing bibliography, and the vertical temperature and salinity profiles related to its extremes over the Bay of Biscay area, show that the obtained time series accurately reflect the IPC-Navidad variability. Once a time series for the evolution of the SST signal of the current over the last decades is well established, this time series is used to propose a physical mechanism in relation to the variability of the IPC-Navidad, involving both atmospheric and oceanic variables. According to the proposed mechanism, an atmospheric circulation anomaly observed in both the 500 hPa and the surface levels generates atmospheric surface level pressure, wind-stress and heat-flux anomalies. In turn, those surface level atmospheric anomalies induce mutually coherent SST and sea level anomalies over the North Atlantic area, and locally, in the Bay of Biscay area. These anomalies, both locally over the Bay of Biscay area and over the North Atlantic, are in agreement with several mechanisms that have separately been related to the variability of the IPC-Navidad, i.e. the south-westerly winds, the joint effect of baroclinicity and relief (JEBAR) effect, the topographic beta effect and a weakened North Atlantic gyre.
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