Influence of the barotropic mean flow on the width and the structure of the Atlantic Equatorial Deep Jets.

Claus, Martin , Greatbatch, Richard John and Brandt, Peter (2014) Influence of the barotropic mean flow on the width and the structure of the Atlantic Equatorial Deep Jets. Open Access Journal of Physical Oceanography, 44 . pp. 2485-2497. DOI 10.1175/JPO-D-14-0056.1.

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Abstract

A representation of an equatorial basin mode excited in a shallow water model for a single high order baroclinic vertical normal mode is used as a simple model for the equatorial deep jets. The model is linearized about both a state of rest and a barotropic mean flow corresponding to the observed Atlantic Equatorial Intermediate Current System. We found that the eastward mean flow associated with the North and South Intermediate Counter Currents (NICC and SICC, respectively) effectively shields the Equator from off-equatorial Rossby waves. The westward propagation of these waves is blocked and focusing on the Equator due to beta dispersion is prevented. This leads to less energetic jets along the Equator. On the other hand, the westward barotropic mean flow along the Equator reduces the gradient of absolute vorticity and hence widens the cross-equatorial structure of the basin mode. Increasing lateral viscosity predominantly affects the width of the basin modes’ Kelvin wave component in the presence of the mean flow while the Rossby wave is confined by the flanking NICC and SICC. Independent of the presence of the mean flow, the application of sufficient lateral mixing also hinders the focusing of off-equatorial Rossby waves, which is hence an unlikely feature of a low-frequency basin mode in the real ocean.

Document Type: Article
Additional Information: WOS:000341334300013
Keywords: Equatorial deep jets; Atlantic Ocean; Baroclinic flows; Barotropic mean flow; Ocean dynamics; Waves; oceanic; Interannual variability; Tropical variability; INTERNAL WAVE INTERACTIONS; ATLANTIC-OCEAN; VARIABILITY; BASIN MODE;
Research affiliation: OceanRep > SFB 754 > A4
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
OceanRep > SFB 754
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1175/JPO-D-14-0056.1
ISSN: 0022-3670
Projects: MiKlip, MODINI, SFB754, Future Ocean
Date Deposited: 29 Aug 2014 10:42
Last Modified: 12 Apr 2018 12:48
URI: http://oceanrep.geomar.de/id/eprint/25482

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