New geophysical evidences of erosion at the base of the Walvis Ridge by the Antarctic Bottom Water (AABW)

2007 ◽  
Author(s):  
M. A. Gorini* ◽  
J. R. Derntl ◽  
K. Owolabi ◽  
C. G. Silva
Keyword(s):  
Bottom Water ◽  
Antarctic Bottom Water ◽  
Walvis Ridge ◽  
The Antarctic

The features of Antarctic Bottom Water in the fracture zones at 7-10 deg. N of the Mid-Atlantic ridge

2020 ◽  
Author(s):  
Valentina Volkova ◽  
Alexander Demidov ◽  
Fedor Gippius
Keyword(s):  
Bottom Water ◽  
Historical Data ◽  
Water Mass ◽  
Main Task ◽  
Bottom Relief ◽  
Antarctic Bottom Water ◽  
Fracture Zones ◽  
Mid Atlantic Ridge ◽  
Proper Estimation ◽  
The Antarctic

<p>Despite the fact that there are numerous estimates of the Antarctic Bottom Water (AABW) formation and transport, its evolution and distribution pathways are still debatable (Morozov E.G. et al., 2010).</p><p>The main task of this work was to identify the structure and transport of deep and bottom water mass of the fracture zones (7 40', Vernadsky and Doldrums). The research is based on new data (multibeam bottom relief, temperature, salinity, velocity) obtained during the research cruise on the RV "Akademik Nikolaj Strakhov" in October-November 2019 and WODB18 historical data.</p><p>The main result of the research is proper estimation of the AABW and LNADW transport, which takes into consideration the influence of fracture zone morphometry. Accordingly, the preliminary circulation scheme of water masses is obtained.</p>

scholarly journals Can the Topography of Tibetan Plateau Affect the Antarctic Bottom Water?

2021 ◽  
Vol 48 (6) ◽  
Author(s):  
Qin Wen ◽  
Chenyu Zhu ◽  
Zixuan Han ◽  
Zhengyu Liu ◽  
Haijun Yang
Keyword(s):  
Tibetan Plateau ◽  
Bottom Water ◽  
Antarctic Bottom Water ◽  
The Antarctic

Recent recovery of Antarctic Bottom Water formation in the Ross Sea driven by climate anomalies

2021 ◽  
Author(s):  
Alessandro Silvano ◽  
Annie Foppert ◽  
Steve Rintoul ◽  
Paul Holland ◽  
Takeshi Tamura ◽  
...  
Keyword(s):  
Sea Ice ◽  
Continental Shelf ◽  
Bottom Water ◽  
Ross Sea ◽  
Ice Sheet ◽  
Ice Formation ◽  
Depth Range ◽  
Antarctic Bottom Water ◽  
Climate Anomalies ◽  
The Antarctic

<div> <div> <div> <p>Antarctic Bottom Water (AABW) supplies the lower limb of the global overturning circulation, ventilates the abyssal ocean and sequesters heat and carbon on multidecadal to millennial timescales. AABW originates on the Antarctic continental shelf, where strong winter cooling and brine released during sea ice formation produce Dense Shelf Water, which sinks to the deep ocean. The salinity, density and volume of AABW have decreased over the last 50 years, with the most marked changes observed in the Ross Sea. These changes have been attributed to increased melting of the Antarctic Ice Sheet. Here we use in situ observations to document a recovery in the salinity, density and thickness (that is, depth range) of AABW formed in the Ross Sea, with properties in 2018–2019 similar to those observed in the 1990s. The recovery was caused by increased sea ice formation on the continental shelf. Increased sea ice formation was triggered by anomalous wind forcing associated with the unusual combination of positive Southern Annular Mode and extreme El Niño conditions between 2015 and 2018. Our study highlights the sensitivity of AABW formation to remote forcing and shows that climate anomalies can drive episodic increases in local sea ice formation that counter the tendency for increased ice-sheet melt to reduce AABW formation.</p> </div> </div> </div>

scholarly journals The Impact of Open Oceanic Processes on the Antarctic Bottom Water Outflows

2011 ◽  
Vol 41 (10) ◽  
pp. 1941-1957 ◽  
Author(s):  
Shinichiro Kida
Keyword(s):  
Bottom Water ◽  
Water Mass ◽  
Shelf Break ◽  
Weddell Sea ◽  
Antarctic Bottom Water ◽  
Antarctic Continental Shelf ◽  
Deep Channel ◽  
Major Branch ◽  
The Antarctic ◽  
The Impact

Abstract The impact of open oceanic processes on the Antarctic Bottom Water (AABW) outflows is investigated using a numerical model with a focus on outflows that occur through deep channels. A major branch of the AABW outflow is known to occur as an overflow from the Filchner Depression to the Weddell Sea through a deep channel a few hundred kilometers wide and a sill roughly 500 m deep. When this overflow enters the Weddell Sea, it encounters the Antarctic Slope Front (ASF) at the shelf break, a density front commonly found along the Antarctic continental shelf break. The presence of an AABW outflow and the ASF create a v-shaped isopycnal structure across the shelf break, indicating an interaction between the overflow and oceanic processes. Model experiments show the overflow transport to increase significantly when an oceanic wind stress increases the depth of the ASF. This enhancement of overflow transport occurs because the channel walls allow a pressure gradient in the along-slope direction to exist and the overflow transport is geostrophically controlled with its ambient oceanic water at the shelf break. Because the ASF is associated with a lighter water mass that reaches the depth close to that of the channel, an increase in its depth increases the density gradient across the shelf break and therefore the geostrophic overflow transport. The enhancement of overflow transport is also likely to result in a lighter overflow water mass, although such an adjustment of density likely occurs on a much longer time scale than the adjustment of transport.

scholarly journals Decadal Freshening of the Antarctic Bottom Water Exported from the Weddell Sea

2013 ◽  
Vol 26 (20) ◽  
pp. 8111-8125 ◽  
Author(s):  
Loïc Jullion ◽  
Alberto C. Naveira Garabato ◽  
Michael P. Meredith ◽  
Paul R. Holland ◽  
Peggy Courtois ◽  
...  
Keyword(s):  
Bottom Water ◽  
Weddell Sea ◽  
Antarctic Bottom Water ◽  
Atlantic Sector ◽  
Ice Shelves ◽  
Anthropogenic Component ◽  
Deep Layers ◽  
Bottom Waters ◽  
Circumpolar Current ◽  
The Antarctic

Abstract Recent decadal changes in Southern Hemisphere climate have driven strong responses from the cryosphere. Concurrently, there has been a marked freshening of the shelf and bottom waters across a wide sector of the Southern Ocean, hypothesized to be caused by accelerated glacial melt in response to a greater flux of warm waters from the Antarctic Circumpolar Current onto the shelves of West Antarctica. However, the circumpolar pattern of changes has been incomplete: no decadal freshening in the deep layers of the Atlantic sector has been observed. In this study, the authors document a significant freshening of the Antarctic Bottom Water exported from the Weddell Sea, which is the source for the abyssal layer of the Atlantic overturning circulation, and trace its possible origin to atmospheric-forced changes in the ice shelves and sea ice on the eastern flank of the Antarctic Peninsula that include an anthropogenic component. These findings suggest that the expansive and relatively cool Weddell gyre does not insulate the bottom water formation regions in the Atlantic sector from the ongoing changes in climatic forcing over the Antarctic region.

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