Evidence for a Deep Western Boundary Current in the South Indian Ocean

1971 ◽  
Vol 229 (1) ◽  
pp. 18-19 ◽  
Author(s):  
B. A. WARREN
Keyword(s):  
Indian Ocean ◽  
Western Boundary Current ◽  
Western Boundary ◽  
Boundary Current ◽  
The South ◽  
South Indian Ocean ◽  
Deep Western Boundary Current ◽  
South Indian

scholarly journals Deep Western Boundary Current transport variability in the South Atlantic: preliminary results from a pilot array at 34.5° S

2012 ◽  
Vol 9 (2) ◽  
pp. 977-1008 ◽  
Author(s):  
C. S. Meinen ◽  
A. R. Piola ◽  
R. C. Perez ◽  
S. L. Garzoli
Keyword(s):  
Annual Cycle ◽  
Statistical Significance ◽  
South Atlantic ◽  
Western Boundary Current ◽  
Meridional Overturning Circulation ◽  
Western Boundary ◽  
Model Output ◽  
Boundary Current ◽  
The South ◽  
Deep Western Boundary Current

Abstract. The first direct estimates of the temporal variability of the absolute transport of the Deep Western Boundary Current (DWBC) at 34.5° S in the South Atlantic Ocean are obtained using just under one year of data from a line of four pressure-equipped inverted echo sounders. Hydrographic sections collected in 2009 and 2010 confirm the presence of the DWBC, one of the main deep pathways of the Meridional Overturning Circulation, based on neutral density, temperature, salinity, and oxygen values. Both observations confirm that the DWBC reconstitutes itself after breaking into eddies in the western sub-tropical Atlantic near 8° S. The amplitude and spectral character of the DWBC transport variability are comparable with those observed at 26.5° N, where longer records exist, with the DWBC at 34.5° S exhibiting a transport standard deviation of 25 Sv and variations of ~40 Sv occurring within periods as short as a few days. There is little indication of an annual cycle in the DWBC transports, although the observation record is too short to be definitive, and the dominant time scale during the first year of the experiment was about 9–10 days. A "Monte Carlo-style" analysis using 27 yr of model output from the same location as the observations indicates that another 48–60 months of data will be required to encompass a fairly complete span of deep transport variability. The model suggests the presence of an annual cycle in DWBC transport, however the statistical significance of the annual cycle with even 27 yr of model output is low, suggesting that annual period variations in the model are weak as well.

scholarly journals The fate of the Deep Western Boundary Current in the South Atlantic

2015 ◽  
Vol 103 ◽  
pp. 125-136 ◽  
Author(s):  
Silvia L. Garzoli ◽  
Shenfu Dong ◽  
Rana Fine ◽  
Christopher S. Meinen ◽  
Renellys C. Perez ◽  
...  
Keyword(s):  
South Atlantic ◽  
Western Boundary Current ◽  
Western Boundary ◽  
Boundary Current ◽  
The South ◽  
Deep Western Boundary Current

scholarly journals Deep Western Boundary Current transport variability in the South Atlantic: preliminary results from a pilot array at 34.5° S

Ocean Science ◽  
2012 ◽  
Vol 8 (6) ◽  
pp. 1041-1054 ◽  
Author(s):  
C. S. Meinen ◽  
A. R. Piola ◽  
R. C. Perez ◽  
S. L. Garzoli
Keyword(s):  
Annual Cycle ◽  
Statistical Significance ◽  
South Atlantic ◽  
Western Boundary Current ◽  
Meridional Overturning Circulation ◽  
Western Boundary ◽  
Model Output ◽  
Boundary Current ◽  
The South ◽  
Deep Western Boundary Current

Abstract. The first direct estimates of the temporal variability of the absolute transport in the Deep Western Boundary Current (DWBC) at 34.5° S in the South Atlantic Ocean are obtained using just under one year of data from a line of four pressure-equipped inverted echo sounders. Hydrographic sections collected in 2009 and 2010 confirm, based on neutral density, temperature, salinity, and oxygen values, the presence of the DWBC, one of the main deep pathways of the Meridional Overturning Circulation. Both data sets indicate that the DWBC reconstitutes itself after breaking into eddies in the western sub-tropical Atlantic near 8° S. The amplitude and spectral character of the DWBC transport variability are comparable with those observed in the North Atlantic, where longer records exist, with the DWBC at 34.5° S exhibiting a transport standard deviation of 25 Sv and variations of ∼ 40 Sv occurring within periods as short as a few days. There is little indication of an annual cycle in the DWBC transports, although the observational records are too short to be definitive. A Monte Carlo-style analysis using 27 yr of model output from the same location as the observations indicates that about 48–60 months of data will be required to fully assess the deep transport variability. The model suggests the presence of an annual cycle in DWBC transport, however its statistical significance with even 27 yr of model output is low, suggesting that seasonal variations in the model are weak.

scholarly journals Deep Western Boundary Current in the South China Sea

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Chun Zhou ◽  
Wei Zhao ◽  
Jiwei Tian ◽  
Xiaolong Zhao ◽  
Yuchao Zhu ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Western Boundary Current ◽  
The South China Sea ◽  
Western Boundary ◽  
Boundary Current ◽  
The South ◽  
China Sea ◽  
Deep Western Boundary Current

Variability of the Observed Deep Western Boundary Current in the South China Sea

2020 ◽  
Vol 50 (10) ◽  
pp. 2953-2963
Author(s):  
Muping Zhou ◽  
Guihua Wang ◽  
Wenhu Liu ◽  
Changlin Chen
Keyword(s):  
South China Sea ◽  
South China ◽  
Western Boundary Current ◽  
The South China Sea ◽  
Western Boundary ◽  
Boundary Current ◽  
The South ◽  
Northern Boundary ◽  
China Sea ◽  
Deep Western Boundary Current

AbstractThe existence of a deep western boundary current (DWBC) in the South China Sea (SCS) was verified by direct observations from three current moorings deployed from September 2015 to September 2018. The average current speeds observed in the DWBC were around 1 cm s−1 along the northern boundary and 3 cm s−1 along the western boundary. The DWBC demonstrates significant intraseasonal variability in the 30–120-day-period band, which may come from the variability in the Luzon overflow or the eddies in the deep SCS forced by a stable Luzon overflow. In addition, observations found that this DWBC along the northern boundary can reverse its direction meridionally in the spring. Model results suggest that if the Luzon overflow decreases one-third of its typical transport, this current reversal can occur. This behavior can be explained through “relaxation” theory.

scholarly journals Midlatitude–Equatorial Dynamics of a Grounded Deep Western Boundary Current. Part I: Midlatitude Flow and the Transition to the Equatorial Region

2015 ◽  
Vol 45 (10) ◽  
pp. 2457-2469 ◽  
Author(s):  
Gordon E. Swaters
Keyword(s):  
Bottom Topography ◽  
Zonal Flow ◽  
Ocean Basin ◽  
Equatorial Region ◽  
Western Boundary Current ◽  
Western Boundary ◽  
Boundary Current ◽  
Qualitative Properties ◽  
Deep Western Boundary Current ◽  
The Tropics

AbstractA comprehensive theoretical study of the nonlinear hemispheric-scale midlatitude and cross-equatorial steady-state dynamics of a grounded deep western boundary current is given. The domain considered is an idealized differentially rotating, meridionally aligned basin with zonally varying parabolic bottom topography so that the model ocean shallows on both the western and eastern sides of the basin. Away from the equator, the flow is governed by nonlinear planetary geostrophic dynamics on sloping topography in which the potential vorticity equation can be explicitly solved. As the flow enters the equatorial region, it speeds up and becomes increasingly nonlinear and passes through two distinguished inertial layers referred to as the “intermediate” and “inner” inertial equatorial boundary layers, respectively. The flow in the intermediate equatorial region is shown to accelerate and turn eastward, forming a narrow equatorial jet. The qualitative properties of the solution presented are consistent with the known dynamical characteristics of the deep western boundary currents as they flow from the midlatitudes into the tropics. The predominately zonal flow across the ocean basin in the inner equatorial region (and its exit from the equatorial region) is determined in Part II of this study.

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