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| Arzel, Olivier; Huck, Thierry. |
| Atmospheric stochastic forcing associated with the North Atlantic Oscillation (NAO) and intrinsic ocean modes associated with the large-scale baroclinic instability of the North Atlantic Current (NAC) are recognized as two strong paradigms for the existence of the Atlantic Multidecadal Oscillation (AMO). The degree to which each of these factors contribute to the low-frequency variability of the North Atlantic is the central question in this paper. This issue is addressed here using an ocean general circulation model run under a wide range of background conditions extending from a super-critical regime where the oceanic variability spontaneously develops in the absence of any atmospheric noise forcing to a damped regime where the variability requires some... |
| Tipo: Text |
Palavras-chave: Instability; Rossby waves; Climate variability; Interdecadal variability; Multidecadal variability; North Atlantic Oscillation. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00599/71138/69452.pdf |
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| Arzel, Olivier; Huck, Thierry. |
| A simplified coupled ocean-atmosphere model, consisting of a one-layer bidimensional ocean model and a one-layer unidimensional energy balance atmospheric model [J. Clim. 13 (2000) 232] is used to study the unstable interactions between zonal winds and ocean gyres. In a specific range of parameters, decadal variability is found. Anomalies, quite homogeneous zonally, show small-scale wavelength in latitude: perturbations emerge and grow at the southern limb of the intergyre boundary and propagate southward before decaying. The wind stress anomalies are proportional to the meridional gradient of the atmospheric temperature anomalies: this ratio acts as a positive amplification factor, as confirmed by a parameter sensitivity analysis. Assuming... |
| Tipo: Text |
Palavras-chave: Ocean atmosphere system; Air sea interaction; Air sea coupling; Ocean circulation. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-647.pdf |
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| Hochet, Antoine; Huck, Thierry; Arzel, Olivier; Sevellec, Florian; Colin De Verdiere, Alain; Mazloff, Matthew; Cornuelle, Bruce. |
| The North Atlantic is characterized by basin-scale multidecadal fluctuations of the sea surface temperature with periods ranging from 20 to 70 years. One candidate for such a variability is a large-scale baroclinic instability of the temperature gradients across the Atlantic associated with the North Atlantic Current. Because of the long time scales involved, most of the studies devoted to this problem are based on low resolution numerical models leaving aside the effect of explicit meso-scale eddies. How high-frequency motions associated with the meso-scale eddy field affect the basin-scale low-frequency variabiliy is the central question of this study. This issue is addressed using an idealized configuration of an Ocean General Circulation Model at... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00635/74701/74640.pdf |
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