scholarly journals Mean Antarctic Circumpolar Current transport measured in Drake Passage

2016 ◽  
Vol 43 (22) ◽  
Author(s):  
K. A. Donohue ◽  
K. L. Tracey ◽  
D. R. Watts ◽  
M. P. Chidichimo ◽  
T. K. Chereskin
Keyword(s):  
Antarctic Circumpolar Current ◽  
Drake Passage ◽  
Current Transport ◽  
Circumpolar Current

scholarly journals Thermohaline and Wind Forcing of a Circumpolar Channel withBlocked Geostrophic Contours

2002 ◽  
Vol 32 (9) ◽  
pp. 2520-2540 ◽  
Author(s):  
Daniel Borowski ◽  
Rüdiger Gerdes ◽  
Dirk Olbers
Keyword(s):  
Potential Energy ◽  
Antarctic Circumpolar Current ◽  
Drake Passage ◽  
Wind Forcing ◽  
Wind Effect ◽  
Current Transport ◽  
Leading Order ◽  
Meridional Gradient ◽  
Circumpolar Current ◽  
The Antarctic

Abstract The Antarctic Circumpolar Current is governed by unique dynamics. Because the latitude belt of Drake Passage is not zonally bounded by continents, the Sverdrup theory does not apply to the Antarctic Circumpolar Current. However, most of the geostrophic contours are blocked at Drake Passage, which provides an important dynamic constraint for the vorticity equation of the depth averaged flow. This study addresses the effects of thermohaline and wind forcing on the large-scale transport of a circumpolar current with blocked geostrophic contours. Various numerical experiments with three different idealized model geometries were conducted. Based on the results and theoretical arguments, the authors promote an indirect wind effect on the circumpolar current: while the direct effects of the wind in driving the circumpolar current through a vertical transfer of the applied wind stress are of minor importance, the wind does substantially influence the circumpolar current transport through its effects on the density field. This indirect wind effect is discussed in two steps. First, at the latitudes of the circumpolar current and longitudes where the geostrophic contours are blocked, the meridional gradient of the mass transport streamfunction is to leading order balanced by the meridional gradient of the baroclinic potential energy. This balance implies that the total transport is to leading order baroclinic and that the deep transport is small. For this statement, some theoretical arguments are offered. Second, a simplified analytical model is used to obtain the distribution of the baroclinic potential energy. Assuming an advective–diffusive balance for the densities in the deep downwelling northern branch of the Deacon cell, this model reproduces the qualitative dependence of the circumpolar current transport on the imposed wind and thermohaline forcing as well as on the turbulent diffusivities.

scholarly journals Intrinsic variability of the Antarctic Circumpolar Current system: low- and high-frequency fluctuations of the Argentine Basin flow

Ocean Science ◽  
2014 ◽  
Vol 10 (2) ◽  
pp. 201-213 ◽  
Author(s):  
G. Sgubin ◽  
S. Pierini ◽  
H. A. Dijkstra
Keyword(s):  
High Frequency ◽  
Antarctic Circumpolar Current ◽  
Current System ◽  
Low Frequency ◽  
Drake Passage ◽  
Ocean Model ◽  
Intrinsic Variability ◽  
Circumpolar Current ◽  
The Antarctic ◽  
Argentine Basin

Abstract. In this paper, the variability of the Antarctic Circumpolar Current system produced by purely intrinsic nonlinear oceanic mechanisms is studied through a sigma-coordinate ocean model, implemented in a large portion of the Southern Ocean at an eddy-permitting resolution under steady surface heat and momentum fluxes. The mean transport through the Drake Passage and the structure of the main Antarctic Circumpolar Current fronts are well reproduced by the model. Intrinsic variability is found to be particularly intense in the Subantarctic Front and in the Argentine Basin, on which further analysis is focused. The low-frequency variability at interannual timescales is related to bimodal behavior of the Zapiola Anticyclone, with transitions between a strong and collapsed anticyclonic circulation in substantial agreement with altimeter observations. Variability on smaller timescales shows clear evidence of topographic Rossby-wave propagation along the eastern and southern flanks of the Zapiola Rise and of mesoscale eddies, also in agreement with altimeter observations. The analysis of the relationship between the low- and high-frequency variability suggests possible mechanisms of mutual interaction.

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