Changes in Antarctic Bottom Water properties in the western South Atlantic in the late 1980s

1996 ◽  
Vol 101 (C4) ◽  
pp. 8957-8970 ◽  
Author(s):  
Victoria J. Coles ◽  
Michael S. McCartney ◽  
Donald B. Olson ◽  
William M. Smethie
Keyword(s):  
Bottom Water ◽  
South Atlantic ◽  
Antarctic Bottom Water ◽  
Water Properties

scholarly journals Trends in the deep Southern Ocean (1958-2010): Implications for Antarctic Bottom Water properties and volume export

2013 ◽  
Vol 118 (9) ◽  
pp. 4213-4227 ◽  
Author(s):  
Marina Azaneu ◽  
Rodrigo Kerr ◽  
Mauricio M. Mata ◽  
Carlos A. E. Garcia
Keyword(s):  
Southern Ocean ◽  
Bottom Water ◽  
Antarctic Bottom Water ◽  
Water Properties

scholarly journals An update of anthropogenic CO2 storage rates in the western South Atlantic basin and the role of Antarctic Bottom Water

2012 ◽  
Vol 94 ◽  
pp. 197-203 ◽  
Author(s):  
A.F. Ríos ◽  
A. Velo ◽  
P.C. Pardo ◽  
M. Hoppema ◽  
F.F. Pérez
Keyword(s):  
Bottom Water ◽  
Co2 Storage ◽  
South Atlantic ◽  
Antarctic Bottom Water ◽  
Atlantic Basin ◽  
Anthropogenic Co2

scholarly journals Assessment of the representation of Antarctic Bottom Water properties in the ECCO2 reanalysis

Ocean Science ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 923-946 ◽  
Author(s):  
M. Azaneu ◽  
R. Kerr ◽  
M. M. Mata
Keyword(s):  
Southern Ocean ◽  
Ocean Circulation ◽  
Bottom Water ◽  
Potential Temperature ◽  
World Ocean ◽  
Volume Transport ◽  
Weddell Sea ◽  
Antarctic Bottom Water ◽  
Water Properties ◽  
The Absolute

Abstract. We analyzed the ability of the Estimating the Circulation and Climate of the Ocean – Phase II (ECCO2) reanalysis to represent the hydrographic properties and variability of Antarctic Bottom Water (AABW) in the Southern Ocean. We used a 20-year (1992–2011) observational database to perform comparisons of hydrographic properties and reanalysis output for the same time period. Four case studies based on current meter data and the AABW volume transport estimates previously reported in the literature were also evaluated. The opening and maintenance of an oceanic polynya in the Weddell Sea sector is observed after 2004 in the reanalysis product. Moreover, intense deep water production due to deep convection occurs, which leads to a scenario in which the Weddell Sea is flooded with AABW. For this reason, our analyses focused on the period that was identified as more reliable (1992–2004). The main Southern Ocean oceanographic features, as well as the characteristic shape of the regional potential temperature–salinity (θ–S) diagrams, are coincident with observations. However, the reanalysis output produces surface waters that are generally denser than observations due to the reproduction of waters that are generally saltier than expected, which probably resulted from the strong seasonality of sea ice concentrations. Bottom waters are warmer and less dense, while intermediate waters are statistically closest to the observations. The differences in bottom water properties are partially due to the inability of the reanalysis to properly reproduce the formation and export of dense waters from the shelf and the consequent absence of the densest AABW variety for most of the analyzed period. Despite differences in the absolute values, the upper AABW limit (γn ≥ 28.27 kg m−3) and AABW occupied area estimates are coincident with the observations in the World Ocean Circulation Experiment (WOCE) repeat sections SR2 and SR4. Moreover, the AABW volume export and current velocity variability are correlated with the observed time series in the most important region of dense water export (i.e., the Weddell Sea). Despite the consistency in terms of variability, the absolute volume transport and velocity estimates are underrepresented in all cases.

scholarly journals Assessment of the ECCO2 reanalysis on the representation of Antarctic Bottom Water properties

2014 ◽  
Vol 11 (2) ◽  
pp. 1023-1091 ◽  
Author(s):  
M. Azaneu ◽  
R. Kerr ◽  
M. M. Mata
Keyword(s):  
Southern Ocean ◽  
Case Studies ◽  
Bottom Water ◽  
Potential Temperature ◽  
Volume Transport ◽  
Reanalysis Data ◽  
Weddell Sea ◽  
Good Representation ◽  
Antarctic Bottom Water ◽  
Water Properties

Abstract. We analyzed the ability of the Estimating the Circulation and Climate of the Ocean – Phase II (ECCO2) reanalysis to represent the hydrographic properties and variability of the Antarctic Bottom Water (AABW) in the Southern Ocean. We used a twenty-year observational database to perform comparisons of hydrographic properties and reanalysis data for the same time period (1992–2011). In addition, we evaluated four case studies based on current meter data and the AABW volume transport estimates previously reported in the literature. The main Southern Ocean oceanographic features, as well as the characteristic shape of the regional potential temperature–salinity (θ–S) diagrams, are adequately represented by the reanalysis. However, the opening of an oceanic polynya in the Weddell Sea Sector, which has been clearly visible since 2005, contributed to an unrealistic representation of the hydrographic properties of the Southern Ocean primarily after 2004. In this sense, our analyses focused on the period that was identified as more reliable (1992–2004). In general, the reanalysis data showed surface waters that were warmer, saltier, and denser than observations, which may have resulted from the absence of Ice Shelf Water and from the overestimation of sea ice concentrations that limit oceanic heat loss during austral winters. Intermediate waters were generally colder, fresher, and denser than observations, whereas deep waters were warmer and less dense. These differences in deep water properties were partially a result of the inability to reproduce the densest AABW variety by reanalysis for most of the analyzed period and also because of the model's relatively coarse vertical resolution. Despite differences in absolute values, the upper AABW limit (γn ≥ 28.27 kg m−3) and AABW occupied area were well represented in the WOCE repeat sections SR2 and SR4 for the studied periods. In section WOCE SR3, however, the estimates from the differences were not as well correlated, and the AABW layer thickness was underrepresented. The case studies showed a good representation of the AABW volume export and current velocity variability in the most important region of dense water export (i.e., the Weddell Sea). The exception is the AABW volume transport near the Kerguelen Plateau, in which the rugged local bathymetry and the relatively coarse model resolution hampered a fair representation of the transport variability by the reanalysis. Despite the consistency in terms of variability, absolute volume transport, and velocity, estimates were underrepresented in all cases. Moreover, the reanalysis was capable of reproducing the general variability pattern and trends of the AABW hydrographic properties reported by previous studies. Therefore, the ECCO2 data from the 1992–2004 period was considered adequate for investigating the circulation of the AABW and variability of the hydrographic properties, whereas data from the latter period (2005–2011) must be given careful attention.

Antarctic Bottom Water temperature changes in the western South Atlantic from 1989 to 2014

2014 ◽  
Vol 119 (12) ◽  
pp. 8567-8577 ◽  
Author(s):  
Gregory C. Johnson ◽  
Kristene E. McTaggart ◽  
Rik Wanninkhof
Keyword(s):  
Water Temperature ◽  
Bottom Water ◽  
South Atlantic ◽  
Antarctic Bottom Water ◽  
Bottom Water Temperature ◽  
Temperature Changes

scholarly journals Thermohaline structure of Antarctic Bottom Water \vspace *{.6ex} in the abyssal basins of the South Atlantic

2019 ◽  
Vol 19 (5) ◽  
pp. 1-9 ◽  
Author(s):  
D. I. Frey ◽  
E. G. Morozov ◽  
I. Ansorge ◽  
V. V. Fomin ◽  
N. A. Diansky ◽  
...  
Keyword(s):  
Bottom Water ◽  
South Atlantic ◽  
Antarctic Bottom Water ◽  
The South ◽  
Thermohaline Structure

Warming trend in Antarctic Bottom Water in the Vema Channel in the South Atlantic

2021 ◽  
Author(s):  
Edmo J. D. Campos ◽  
Mathias C. Caspel ◽  
Walter Zenk ◽  
Eugene G. Morozov ◽  
Dmitry I. Frey ◽  
...  
Keyword(s):  
Bottom Water ◽  
Warming Trend ◽  
South Atlantic ◽  
Antarctic Bottom Water ◽  
The South

Major Change in Atlantic Deep and Bottom Waters 700,000 yr Ago: Benthonic Foraminiferal Evidence from the South Atlantic

1982 ◽  
Vol 17 (1) ◽  
pp. 26-38 ◽  
Author(s):  
L. C. Peterson ◽  
G. P. Lohmann
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Bottom Water ◽  
Sediment Cores ◽  
North Atlantic Deep Water ◽  
South Atlantic ◽  
Antarctic Bottom Water ◽  
The South ◽  
Circumpolar Deep Water ◽  
Bottom Waters

AbstractIn the modern South Atlantic the transition between deep water and bottom water is marked by a clear change in the associated benthonic foraminiferal fauna. Uvigerina and Globocassidulina characterize oxygen-poor Circumpolar Deep Water which has long been isolated from the surface. Planulina and miliolids are found associated with the more newly formed, oxygen-rich North Atlantic Deep Water. Antarctic Bottom Water is characterized by “Epistominella” umbonifera. Analysis of the benthonic foraminiferal faunas in two sediment cores recovered from the Vema and Hunter Channels in the western South Atlantic shows that the level of the transition between deep and bottom waters shallowed sharply about 700,000 yr ago. This rise indicates a sharp, sustained increase in the volume of bottom water flowing through the South Atlantic after this time. Prior to about 700,000 yr ago, the amount of Antarctic Bottom Water entering the western South Atlantic was greatly reduced and Circumpolar Deep Water apparently accounted for the bulk of northward flow. Production of southward-flowing North Atlantic Deep Water seems not to have been affected. The timing of this change in circulation regime suggests a possible causal link to similar changes in records of terrestrial and sea-surface climate.

scholarly journals Ventilation of the abyss in the Atlantic sector of the Southern Ocean

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Camille Hayatte Akhoudas ◽  
Jean-Baptiste Sallée ◽  
F. Alexander Haumann ◽  
Michael P. Meredith ◽  
Alberto Naveira Garabato ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Bottom Water ◽  
Climate Models ◽  
Deep Ocean ◽  
Analytical Framework ◽  
Weddell Sea ◽  
Global Ocean ◽  
Shelf Water ◽  
Antarctic Bottom Water ◽  
Atlantic Sector

AbstractThe Atlantic sector of the Southern Ocean is the world’s main production site of Antarctic Bottom Water, a water-mass that is ventilated at the ocean surface before sinking and entraining older water-masses—ultimately replenishing the abyssal global ocean. In recent decades, numerous attempts at estimating the rates of ventilation and overturning of Antarctic Bottom Water in this region have led to a strikingly broad range of results, with water transport-based calculations (8.4–9.7 Sv) yielding larger rates than tracer-based estimates (3.7–4.9 Sv). Here, we reconcile these conflicting views by integrating transport- and tracer-based estimates within a common analytical framework, in which bottom water formation processes are explicitly quantified. We show that the layer of Antarctic Bottom Water denser than 28.36 kg m$$^{-3}$$ - 3 $$\gamma _{n}$$ γ n is exported northward at a rate of 8.4 ± 0.7 Sv, composed of 4.5 ± 0.3 Sv of well-ventilated Dense Shelf Water, and 3.9 ± 0.5 Sv of old Circumpolar Deep Water entrained into cascading plumes. The majority, but not all, of the Dense Shelf Water (3.4 ± 0.6 Sv) is generated on the continental shelves of the Weddell Sea. Only 55% of AABW exported from the region is well ventilated and thus draws down heat and carbon into the deep ocean. Our findings unify traditionally contrasting views of Antarctic Bottom Water production in the Atlantic sector, and define a baseline, process-discerning target for its realistic representation in climate models.

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