Internal and forced variability along a section between Greenland and Portugal in the CLIPPER Atlantic model
|Author(s)||Treguier Anne-Marie1, Gourcuff Claire5, Lherminier Pascale5, Mercier Herle1, Barnier Bernard2, Madec Gurvan3, Molines Jean-Marc2, Penduff Thierry2, Czeschel Lars4, Boning Claus4|
|Affiliation(s)||1 : CNRS, IFREMER, UBO, Lab Phys Oceans, Brest, France.
2 : Univ Grenoble 1, Lab Ecoulements Geophys & Ind, Grenoble, France.
3 : Univ Paris 06, LOCEAN, Lab Oceanog & Climat, Paris, France.
4 : IFM GEOMAR, Kiel, Germany.
|Source||Ocean Dynamics (1616-7341) (Springer), 2006-12 , Vol. 56 , N. 5-6 , P. 568-580|
|WOS© Times Cited||12|
|Keyword(s)||Ocean model, Thermohaline circulation, North Atlantic, Climate variability, Oceanography|
|Abstract||Numerical models are used to estimate the meridional overturning and transports along the paths of two hydrographic cruises, carried out in 1997 and 2002 from Greenland to Portugal. We have examined the influence of the different paths of the two cruises and found that it could explain 0.4 to 2 Sv of difference in overturning (the precise value is model-dependent). Models show a decrease in the overturning circulation between 1997 and 2002, with different amplitudes. The CLIPPER ATL6 model reproduces well the observed weakening of the overturning in density coordinates between the cruises; in the model, the change is due to the combination of interannual and high-frequency forcing and internal variability associated with eddies and meanders. Examination of the z-coordinate overturning reveals model-data discrepancies: the vertical structure in the models does not change as much as the observed one. The East Greenland current variability is mainly wind-forced in the ATL6 model, while fluctuations due to eddies and instabilities explain a large part of the North Atlantic Current variability. The time-residual transport of dense water and heat due to eddy correlations between currents and properties is small across this section, which is normal to the direction of the main current.|