Deep Argo reveals bottom water properties and pathways in the Australian‐Antarctic Basin

2021 ◽  
Author(s):  
Annie Foppert ◽  
Stephen R. Rintoul ◽  
Sarah G. Purkey ◽  
Nathalie Zilberman ◽  
Taiyo Kobayashi ◽  
...  
Keyword(s):  
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 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.

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 Seasonal variability of bottom water properties off Adélie Land, Antarctica

2000 ◽  
Vol 105 (C3) ◽  
pp. 6531-6540 ◽  
Author(s):  
Yasushi Fukamachi ◽  
Masaaki Wakatsuchi ◽  
Keisuke Taira ◽  
Shoji Kitagawa ◽  
Shuki Ushio ◽  
...  
Keyword(s):  
Seasonal Variability ◽  
Bottom Water ◽  
Water Properties

scholarly journals Impact of West Antarctic ice shelf melting on Southern Ocean hydrography

2020 ◽  
Vol 14 (7) ◽  
pp. 2205-2216
Author(s):  
Yoshihiro Nakayama ◽  
Ralph Timmermann ◽  
Hartmut H. Hellmer
Keyword(s):  
Southern Ocean ◽  
Bottom Water ◽  
Ross Sea ◽  
Model Simulation ◽  
Weddell Sea ◽  
Shelf Water ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Water Properties ◽  
West Antarctic

Abstract. Previous studies show accelerations of West Antarctic glaciers, implying that basal melt rates of these glaciers were previously small and increased in the middle of the 20th century. This enhanced melting is a likely source of the observed Ross Sea (RS) freshening, but its long-term impact on the Southern Ocean hydrography has not been well investigated. Here, we conduct coupled sea ice–ice shelf–ocean simulations with different levels of ice shelf melting from West Antarctic glaciers. Freshening of RS shelf and bottom water is simulated with enhanced West Antarctic ice shelf melting, while no significant changes in shelf water properties are simulated when West Antarctic ice shelf melting is small. We further show that the freshening caused by glacial meltwater from ice shelves in the Amundsen and Bellingshausen seas can propagate further downstream along the East Antarctic coast into the Weddell Sea. The freshening signal propagates onto the RS continental shelf within a year of model simulation, while it takes roughly 5–10 and 10–15 years to propagate into the region off Cape Darnley and into the Weddell Sea, respectively. This advection of freshening modulates the shelf water properties and possibly impacts the production of Antarctic Bottom Water if the enhanced melting of West Antarctic ice shelves continues for a longer period.

Physico-chemical water properties and flora diversity under the old mining load influence (Rudnansky creek, Slovakia)

2015 ◽  
Vol 10 (2) ◽  
pp. 123-131
Author(s):  
Lenka Angelovičová ◽  
Zuzana Boguská ◽  
Danica Fazekašová
Keyword(s):  
Water Properties ◽  
Physico Chemical ◽  
Flora Diversity ◽  
Chemical Water
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