The physical environmental conditions for biogeochemical differences along the Antarctic Circumpolar Current in the Atlantic Sector during late austral summer 2012

Abstract The vertical dispersion of a tracer released on a density surface near 1500-m depth in the Antarctic Circumpolar Current west of Drake Passage indicates that the diapycnal diffusivity, averaged over 1 yr and over tens of thousands of square kilometers, is (1.3 ± 0.2) × 10−5 m2 s−1. Diapycnal diffusivity estimated from turbulent kinetic energy dissipation measurements about the area occupied by the tracer in austral summer 2010 was somewhat less, but still within a factor of 2, at (0.75 ± 0.07) × 10−5 m2 s−1. Turbulent diapycnal mixing of this intensity is characteristic of the midlatitude ocean interior, where the energy for mixing is believed to derive from internal wave breaking. Indeed, despite the frequent and intense atmospheric forcing experienced by the Southern Ocean, the amplitude of finescale velocity shear sampled about the tracer was similar to background amplitudes in the midlatitude ocean, with levels elevated to only 20%–50% above the Garrett–Munk reference spectrum. These results add to a long line of evidence that diapycnal mixing in the interior middepth ocean is weak and is likely too small to dictate the middepth meridional overturning circulation of the ocean.

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Changes in the Atlantic Sector of the Southern Ocean estimated from the CESM Last Millennium Ensemble

Antarctic Science ◽

10.1017/s0954102018000433 ◽

2019 ◽

Vol 31 (1) ◽

pp. 37-51 ◽

Cited By ~ 2

Author(s):

Ilana Wainer ◽

Peter R. Gent

Keyword(s):

Time Series ◽

Standard Deviation ◽

Wind Stress ◽

Antarctic Circumpolar Current ◽

Current System ◽

Intermediate Water ◽

Atlantic Sector ◽

Southward Shift ◽

Circumpolar Current ◽

The Antarctic

AbstractThe changes in the Antarctic Circumpolar Current system associated with the Polar, sub-Antarctic and Subtropical Fronts in the Atlantic are examined in a ten-member ensemble using the Community Earth System Model. Results for the ensemble average mean show that the Polar Front at 25°W shifts to the south by 0.8° during 1970–2000 compared to its mean latitude over the period 1050–1950. This shift is significant because it is more than twice the standard deviation of the mean latitude time series during 1050–1950. The shift is caused by a slight southward displacement of the Antarctic Circumpolar Current, which in turn is caused by a southward shift in the latitude of the maximum zonal wind stress. The sub-Antarctic Front also shows a small southward shift after 1970, with a maximum latitudinal displacement of 0.2°. However, this shift is not significant compared to the standard deviation of the time series during 1050–1950. The Subtropical Front does not change its latitude during 1970–2000 compared to 1050–2000 because there is very little change in the wind-stress curl in the subtropics. Differences in temperature and salinity throughout the water column at 25°W reveal that during 1970–2000 there is freshening of Antarctic Intermediate Water, whereas the Circumpolar Deep Water becomes saltier.

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Nonlinear Differential Equations Modeling the Antarctic Circumpolar Current

Journal of Mathematical Fluid Mechanics ◽

10.1007/s00021-021-00618-7 ◽

2021 ◽

Vol 23 (4) ◽

Author(s):

Jifeng Chu ◽

Kateryna Marynets

Keyword(s):

Fixed Point ◽

Differential Equations ◽

Boundary Conditions ◽

Topological Degree ◽

Antarctic Circumpolar Current ◽

Fixed Point Theorems ◽

Nonlinear Differential Equations ◽

Existence Results ◽

Circumpolar Current ◽

The Antarctic

AbstractThe aim of this paper is to study one class of nonlinear differential equations, which model the Antarctic circumpolar current. We prove the existence results for such equations related to the geophysical relevant boundary conditions. First, based on the weighted eigenvalues and the theory of topological degree, we study the semilinear case. Secondly, the existence results for the sublinear and superlinear cases are proved by fixed point theorems.

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