scholarly journals Volume transport of the Antarctic Circumpolar Current: Production and validation of a 20 year long time series obtained from in situ and satellite observations

2014 ◽  
Vol 119 (8) ◽  
pp. 5407-5433 ◽  
Author(s):  
Zoé Koenig ◽  
Christine Provost ◽  
Ramiro Ferrari ◽  
Nathalie Sennéchael ◽  
Marie-Hélène Rio
Keyword(s):  
Time Series ◽  
Antarctic Circumpolar Current ◽  
Volume Transport ◽  
Satellite Observations ◽  
Long Time Series ◽  
Long Time ◽  
Current Production ◽  
Circumpolar Current ◽  
The Antarctic

scholarly journals Topographic Control of Southern Ocean Gyres and the Antarctic Circumpolar Current: A Barotropic Perspective

2019 ◽  
Vol 49 (12) ◽  
pp. 3221-3244 ◽  
Author(s):  
Ryan D. Patmore ◽  
Paul R. Holland ◽  
David R. Munday ◽  
Alberto C. Naveira Garabato ◽  
David P. Stevens ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Antarctic Circumpolar Current ◽  
Large Scale ◽  
Volume Transport ◽  
Topographic Features ◽  
Conservation Of Momentum ◽  
Ridge Width ◽  
Circumpolar Current ◽  
The Antarctic ◽  
Ridge Geometry

AbstractIn the Southern Ocean the Antarctic Circumpolar Current is significantly steered by large topographic features, and subpolar gyres form in their lee. The geometry of topographic features in the Southern Ocean is highly variable, but the influence of this variation on the large-scale flow is poorly understood. Using idealized barotropic simulations of a zonal channel with a meridional ridge, it is found that the ridge geometry is important for determining the net zonal volume transport. A relationship is observed between ridge width and volume transport that is determined by the form stress generated by the ridge. Gyre formation is also highly reliant on the ridge geometry. A steep ridge allows gyres to form within regions of unblocked geostrophic (f/H) contours, with an increase in gyre strength as the ridge width is reduced. These relationships among ridge width, gyre strength, and net zonal volume transport emerge to simultaneously satisfy the conservation of momentum and vorticity.

scholarly journals Modeling a turbulence effect in formation of the Antarctic Circumpolar Current

2006 ◽  
Vol 24 (12) ◽  
pp. 3191-3196 ◽  
Author(s):  
J. Heinloo ◽  
A. Toompuu
Keyword(s):  
Simple Model ◽  
Antarctic Circumpolar Current ◽  
Volume Transport ◽  
Hydrographic Data ◽  
Geostrophic Balance ◽  
Turbulence Effect ◽  
Additive Correction ◽  
Circumpolar Current ◽  
Set Up ◽  
The Antarctic

Abstract. A simple model to determine a turbulence effect in formation of the Antarctic Circumpolar Current (ACC) is suggested. The model is founded on the theory of rotationally anisotropic turbulence and is set up as a generalization of the geostrophic description of the Antarctic Circumpolar Current (ACC). It predicts the turbulence effect as an additive correction to the flow velocity predicted by the geostrophic balance. The correction, calculated from the optimally analyzed hydrographic data in the Southern Ocean, results in an increased ACC total baroclinic volume transport and in a shift in the current velocity maximum to the south, if compared with the pure geostrophic estimate.

Characterization of the ocean mesoscale eddies in the Antarctic Circumpolar Current from in situ, model and remotely sensed data

2020 ◽  
Author(s):  
Yuri Cotroneo ◽  
Lavinia Patara ◽  
Milena Menna ◽  
Pierpaolo Falco ◽  
Jan Klaus Rieck ◽  
...  
Keyword(s):  
Antarctic Circumpolar Current ◽  
Mesoscale Eddies ◽  
Ocean Dynamics ◽  
Joint Analysis ◽  
Spatial And Temporal Variability ◽  
The South ◽  
Eddy Characteristics ◽  
Circumpolar Current ◽  
The Antarctic

<p>Mesoscale variability and associated eddy fluxes play crucial roles in the ocean dynamics, transport of water mass properties and ecology of the upper ocean. In the Southern Hemisphere, where the nearly zonal flow of the Antarctic Circumpolar Current (ACC) acts as a barrier to the direct poleward transport toward the Antarctica, the eddy flux across the ACC is the main mechanism that guarantees the heat budget and distributes physical and biogeochemical properties between subtropical and polar regions. We focused on a high dynamical region located between the South-West Indian Ridge and the South Pacific Ridge. In this area, the interaction between the ACC and the major bathymetric features produces relatively large values of eddy kinetic energy and eddy heat fluxes as well as a relevant forcing for the ACC path.</p><p>The aim of this study is to evaluate the actual efficiency of mesoscale eddies to exchange heat and other properties across the different ACC fronts and to describe the vertical properties of the eddies, their tracks and evolution. To this end, we used in-situ and satellite data in conjunction with a hindcast simulation from 1958 to 2018 performed with a 1/10° ocean biogeochemistry model.</p><p>Eddies are identified and tracked in both the model output and altimetry data while their thermohaline properties and vertical extension are described using model outputs and in situ data, which include available repeated XBT sections (i.e. New Zealand – Antarctica and Hobart – Antarctica) and Argo float profiles located inside these structures.</p><p>Thanks to the joint analysis of model and observational data, we are able to 1) assess the ability of the 1/10° ocean model of simulating the eddy field properties, and to 2) better interpret the spatial and temporal variability of the observed eddy characteristics in the larger and longer framework of the ocean simulation.</p>

Consistency of observed sea surface height changes, bottom pressure changes and temperature, salinity variations in a South Atlantic transect of the Antarctic Circumpolar Current

2020 ◽  
Author(s):  
Alisa Yakhontova ◽  
Roelof Rietbroek ◽  
Jens Schröter ◽  
Nadja Jonas ◽  
Christina Lück ◽  
...  
Keyword(s):  
Antarctic Circumpolar Current ◽  
Sea Surface Height ◽  
South Atlantic ◽  
Sea Surface ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Satellite Gravimetry ◽  
Circumpolar Current ◽  
The Antarctic

<p>Improved estimates of temperature, salinity, and sea surface height changes are computed from radar altimetry, satellite gravimetry and Argo profiles, and validated by the in situ ocean bottom pressure measurements in a South Atlantic transect of the Antarctic Circumpolar current. Using satellite gravimetry and altimetry observations, separate contributions to the global sea level can be estimated, but a regional solution is more challenging. Furthermore, Argo derived steric sea level change suffers from spatio-temporal sampling problems, and some signals are not well captured, e.g. in the deeper ocean below 2000m, around the boundary currents, in the Arctic or in the shelf/coastal regions. Jointly processing radar altimetry, Argo and data from the Gravity Recovery and Climate Experiment (GRACE), would allow to correct the deficiencies of the individual datasets, and produce observation based estimates of consistent temperature, salinity and sea surface height changes. In order to pave the way for an advanced joint inversion scheme that additionally resolves for temperature and salinity, the observation equations are formulated which link the satellite observations to temperature and salinity at depth. Observations in the South Atlantic region are compared with simulations from the FESOM model in terms of variability and the model data is used to find the spatial coherence of the signals at the sites with the surrounding ocean. The experiment is performed in the Southern Atlantic Ocean, where the estimates can be validated using an array of in situ ocean bottom pressure observations.</p>

scholarly journals Swirling Eddies in the Antarctic May Have Global Impacts

Eos ◽  
2017 ◽  
Author(s):  
Lily Strelich
Keyword(s):  
Antarctic Circumpolar Current ◽  
Volume Transport ◽  
Current Effect ◽  
New Model ◽  
Global Impacts ◽  
Circumpolar Current ◽  
The Antarctic

A new model examines how eddies in the Antarctic Circumpolar Current effect volume transport of the world's strongest current.

scholarly journals Subantarctic and Polar Fronts of the Antarctic Circumpolar Current and Southern Ocean Heat and Freshwater Content Variability: A View from Argo

2016 ◽  
Vol 46 (3) ◽  
pp. 749-768 ◽  
Author(s):  
Donata Giglio ◽  
Gregory C. Johnson
Keyword(s):  
Southern Ocean ◽  
Antarctic Circumpolar Current ◽  
Potential Temperature ◽  
Local Maximum ◽  
Potential Density ◽  
Argo Data ◽  
Circumpolar Current ◽  
The Antarctic ◽  
Ekman Upwelling

AbstractArgo profiling floats initiated a revolution in observational physical oceanography by providing numerous, high-quality, global, year-round, in situ (0–2000 dbar) temperature and salinity observations. This study uses Argo’s unprecedented sampling of the Southern Ocean during 2006–13 to describe the position of the Antarctic Circumpolar Current’s Subantarctic and Polar Fronts, comparing and contrasting two different methods for locating fronts using the same dataset. The first method locates three fronts along dynamic height contours, each corresponding to a local maximum in vertically integrated shear. The second approach locates the fronts using specific features in the potential temperature field, following Orsi et al. Results from the analysis of Argo data are compared to those from Orsi et al. and other more recent studies. Argo spatial resolution is not adequate to resolve annual and interannual movements of the fronts on a circumpolar scale since they are on the order of 1° latitude (Kim and Orsi), which is smaller than the resolution of the gridded product analyzed. Argo’s four-dimensional coverage of the Southern Ocean equatorward of ~60°S is used to quantify variations in heat and freshwater content there with respect to the time-mean front locations. These variations are described during 2006–13, considering both pressure and potential density ranges (within different water masses) and relations to wind forcing (Ekman upwelling and downwelling).

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

2019 ◽  
Vol 31 (1) ◽  
pp. 37-51 ◽  
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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