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Lundi 22 octobre - Jet Jumping: Variability in the Southern Ocean fronts

Par semsou — Dernière modification 12/02/2013 12:30
Quand ? Le 22/10/2012,
de 11:00 à 12:00
Où ? Coriolis
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Participants Chris Chapman (Australian National University)
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Chris Chapman (Australian National University)

 

Title : Jet Jumping: Variability in the Southern Ocean fronts

 

Abstract : Recent observations of the Southern Ocean from fixed moorings and satellite altimetry have revealed that the jets, or “fronts” that make up the Antarctic Circumpolar Current show peculiar variability in the vicinity of large, sub-surface topographic features.  Two (or more) jets that pass near the same topographic feature display anti-correlated behavior, where one jet will increase in strength at the expense of others.  This variability can manifest itself in dramatic ways, with a particular jet changing ``preference” for a topographic feature.  For example, a jet that previously skirted a plateau to the north, can very rapidly shift to skirt the plateau to the south.  Shifts in the latitudinal position of jets of more than 10 degrees have been observed.    


We will present a simple framework explaining this behavior, built on the results of an idealized numerical model. We posit that it is the interaction of turbulent eddies and topographically driven flow in the abyssal layers that explains the observed variation in mean currents observed at the surface and middle layers.  The feedback of eddy – mean flow will also be discussed.   

 

 

 

 

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