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| Ferron, Bruno. |
| The increasing number of oceanic observations calls for the use of synthetic methods to provide consistent analyses of the oceanic variability that will support a better understanding of the underlying mechanisms. In this study, a 1/3 degrees eddy-permitting model of the North Atlantic (from 20 degrees S to 70 degrees N) is combined with a 4D-variational method to estimate the oceanic state from altimeter observations. This resolution allows a better extraction of the physical content of altimeter data since the model spatial scales are more consistent with the data than coarser assimilation exercises because of a lower error in model representativity. Several strategies for the assimilation window are tested through twin experiments carried out under the... |
| Tipo: Text |
Palavras-chave: Ocean modelling; Data assimilation; Variational method; Meso-scale; Sea surface height; Heat transport; Meridional overturning. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00044/15534/12956.pdf |
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| Colin De Verdiere, Alain; Meunier, Thomas; Ollitrault, Michel. |
| A direct method is presented to obtain the meridional overturning and heat transport in oceanic basins from observations under the sole assumptions of geostrophy and hydrostatics. The method is made possible because of the rising Argo float displacements database that can provide a reference level at 1000 dbar for the time mean circulation at 1 degrees x 1 degrees resolution. To achieve the overturning and heat transport objectives, the absolute geostrophic time mean circulation must have nondivergent barotropic transports and this requires the solutions of two Poisson equations with suitable boundary conditions, one for the geopotential at 1000 dbar and one for the barotropic stream function. Applied to the subpolar Atlantic for the period 2000-2009, an... |
| Tipo: Text |
Palavras-chave: Oceanic heat transport; Meridional overturning; Subpolar Atlantic. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00589/70139/68105.pdf |
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| Friedrich, T.; Timmermann, A.; Stichel, T.; Pahnke, K.. |
| Over the past decade, records of the seawater neodymium isotopic composition (epsilon(Nd)) have become a widely used proxy to reconstruct changes in ocean circulation. Our study investigates the transient response of epsilon(Nd) to large-scale ocean circulation changes using an Earth system model of intermediate complexity. It is shown that a weakening of the North Atlantic Deep Water formation results in positive epsilon(Nd) anomalies in the Atlantic and the Pacific below 1000m water depth whereas variations in Antarctic Bottom Water production generate a Pacific-Atlantic dipole pattern of deep ocean epsilon(Nd) changes. Further experiments explore which ocean regions are suitable to record the temporal evolution of the overturning in the North Atlantic... |
| Tipo: Text |
Palavras-chave: Neodymium; Ocean circulation; Meridional overturning; Ocean modeling; Reconstruction. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00289/40055/39405.pdf |
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