Rock material from the Weddell Sea Floor of the South Ocean

2007 ◽  
Vol 1 (5) ◽  
pp. 435-443 ◽  
Author(s):  
N. A. Kurentsova ◽  
T. I. Frolova ◽  
G. B. Udintsev ◽  
I. A. Roshchina
Keyword(s):  
Weddell Sea ◽  
Rock Material ◽  
The South ◽  
Sea Floor ◽  
South Ocean

The role of tides on the carbonate chemistry of a coastal polynya in the south-eastern Weddell Sea

2021 ◽  
Author(s):  
Elise Droste ◽  
Melchor González Dávila ◽  
Juana Magdalena Santana Casiano ◽  
Mario Hoppema ◽  
Gerd Rohardt ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Weddell Sea ◽  
Water Masses ◽  
Total Alkalinity ◽  
The South ◽  
Carbonate Chemistry ◽  
Large Variability ◽  
South Eastern ◽  
Coastal Polynya ◽  
Eastern Weddell Sea

<p>Tides have a large impact on coastal polynyas around Antarctica. We investigate the effect of semi-diurnal tidal cycles on the seawater carbonate chemistry in a coastal polynya hugging the Ekström Ice Shelf in the south-eastern Weddell Sea. This region experiences some of the strongest tides in the Southern Ocean. We assess the implications for the contribution of coastal polynyas to the carbon dioxide (CO<sub>2</sub>) air-sea flux of the Weddell Sea.</p><p>Two site visits, in January 2015 and January 2019, are intercompared in terms of the dissolved inorganic carbon (DIC) concentration, total alkalinity, pH, and CO<sub>2</sub> partial pressure (pCO<sub>2</sub>). The tides induce large variability in the carbonate chemistry of the coastal polynya in the austral summer: DIC concentrations vary between 2174 and 2223 umol kg<sup>-1</sup>.</p><p>The tidal fluctuation in the DIC concentration can swing the polynya from a sink to a source of atmospheric CO<sub>2 </sub>on a semi-diurnal timescale. We attribute these changes to the mixing of different water masses. The amount of variability induced by tides depends on – and is associated with – large scale oceanographic and biogeochemical processes that affect the characteristics and presence of the water masses being mixed, such as the rate of sea ice melt.</p><p>Sampling strategies in Antarctic coastal polynyas should always take tidal influences into account. This would help to reduce biases in our understanding of how coastal polynyas contribute to the CO<sub>2</sub> uptake by the Southern Ocean.</p>

scholarly journals Sources And Movement of Icebergs in the South-West Ross Sea, Antarctica

1989 ◽  
Vol 12 ◽  
pp. 85-88 ◽  
Author(s):  
Harry Keys ◽  
Dennis Fowler
Keyword(s):  
Small Proportion ◽  
Ross Sea ◽  
The South ◽  
Ice Shelf ◽  
Sea Floor ◽  
Ross Ice Shelf ◽  
South West ◽  
Fast Ice ◽  
Western Side ◽  
Coastal Strip

The shape, surface features, composition, and thickness of icebergs trapped annually in a 200 km long coastal strip of fast ice have been examined to determine their sources and movement. The thin western ice front of the Ross Ice Shelf seems to produce about 40% of the icebergs while local glaciers produce the remainder. The ice-shelf icebergs are carried west towards Ross Island then north up the western side of the Ross Sea. A small proportion of them gets trapped mainly by grounding on shallow areas of the sea floor which protrude across the regional long-shore currents.

Atmospheric forcing of coastal polynyas in the south-western Weddell Sea

2015 ◽  
Vol 27 (4) ◽  
pp. 388-402 ◽  
Author(s):  
Verena Haid ◽  
Ralph Timmermann ◽  
Lars Ebner ◽  
Günther Heinemann
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Reanalysis Data ◽  
Ocean Model ◽  
Weddell Sea ◽  
Small Scale ◽  
Atmospheric Conditions ◽  
Atmospheric Forcing ◽  
The South ◽  
Ice Production

AbstractThe development of coastal polynyas, areas of enhanced heat flux and sea ice production strongly depend on atmospheric conditions. In Antarctica, measurements are scarce and models are essential for the investigation of polynyas. A robust quantification of polynya exchange processes in simulations relies on a realistic representation of atmospheric conditions in the forcing dataset. The sensitivity of simulated coastal polynyas in the south-western Weddell Sea to the atmospheric forcing is investigated with the Finite-Element Sea ice-Ocean Model (FESOM) using daily NCEP/NCAR reanalysis data (NCEP), 6 hourly Global Model Europe (GME) data and two different hourly datasets from the high-resolution Consortium for Small-Scale Modelling (COSMO) model. Results are compared for April to August in 2007–09. The two coarse-scale datasets often produce the extremes of the data range, while the finer-scale forcings yield results closer to the median. The GME experiment features the strongest winds and, therefore, the greatest polynya activity, especially over the eastern continental shelf. This results in higher volume and export of High Salinity Shelf Water than in the NCEP and COSMO runs. The largest discrepancies between simulations occur for 2008, probably due to differing representations of the ENSO pattern at high southern latitudes. The results suggest that the large-scale wind field is of primary importance for polynya development.

scholarly journals Sea-floor and sea-ice conditions in the western Weddell Sea, Antarctica, around the wreck of Sir Ernest Shackleton's Endurance

2020 ◽  
Vol 32 (4) ◽  
pp. 301-313 ◽  
Author(s):  
Julian A. Dowdeswell ◽  
Christine L. Batchelor ◽  
Boris Dorschel ◽  
Toby J. Benham ◽  
Frazer D.W. Christie ◽  
...  
Keyword(s):  
Sea Ice ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Weddell Sea ◽  
Energy Conditions ◽  
Mass Wasting ◽  
Sea Floor ◽  
Fine Grained ◽  
Ice Conditions ◽  
Sedimentary System

AbstractMarine-geophysical evidence on sea-floor morphology and shallow acoustic stratigraphy are used to examine the substrate around the location at which Sir Ernest Shackleton's ship Endurance sank in 1915 and on the continental slope-shelf sedimentary system above this site in the western Weddell Sea. Few signs of turbidity-current and mass-wasting activity are found near or upslope of the wreck site, and any such activity was probably linked to full-glacial higher-energy conditions when ice last advanced across the continental shelf. The wreck is well below the maximum depth of iceberg keels and will not have been damaged by ice-keel ploughing. The wreck has probably been draped by only a few centimetres of fine-grained sediment since it sank in 1915. Severe modern sea-ice conditions hamper access to the wreck site. Accessing and investigating the wreck of Endurance in the Weddell Sea therefore represents a significant challenge. An ice-breaking research vessel is required, and even this would not guarantee that the site could be reached. Heavy sea-ice cover at the wreck site, similar to that encountered by Agulhus II during the Weddell Sea Expedition 2019, would also make the launch and recovery of autonomous underwater vehicles and remotely operated vehicles deployed to investigate the Endurance wreck problematic.

Scavenging by megabenthos and demersal fish on the South Georgia slope

2002 ◽  
Vol 14 (1) ◽  
pp. 16-24 ◽  
Author(s):  
Cynthia Yau ◽  
Martin A. Collins ◽  
Phil M. Bagley ◽  
Inigo Everson ◽  
Imants G. Priede
Keyword(s):  
Demersal Fish ◽  
The South ◽  
Low Light ◽  
Sea Floor ◽  
Video Cameras ◽  
South Georgia ◽  
Pectoral Fins ◽  
Camera Systems ◽  
South West ◽  
Antimora Rostrata

The scavenging megafauna of the South Georgia and Shag Rocks slope in the south-west Atlantic (625–1519 m) were investigated using autonomous baited camera systems. Two surveys were conducted: the first in 1997 (13 deployments) used a conventional 35 mm stills camera with a 200 J flash, whilst the second in 2000 (15 deployments) used low-light digital video cameras. The scavenging community responded rapidly to the arrival of bait on the sea floor and was dominated by stone crabs (Lithodidae) and toothfish (Dissostichus eleginoides). Stone crabs took up residence around the bait until it was consumed, with a maximum number of 108 in the field of view after four hours. The most frequently observed crab species was Paralomis formosa. Paralomis spinosissima, Neolithodes diomedea and Lithodes sp., were also observed. Toothfish were the most frequently observed scavenging fish and were seen during all but one deployment, typically making brief visits (1–2 min) to the bait, but appeared startled by the flash in the 1997 survey. Labriform swimming (sculling with the pectoral fins) was the principal form of locomotion in toothfish (0.22 body lengths (BL) sec−1), but they were capable of more rapid sub-carangiform (using caudal trunk and fin) motion (3 BL sec−1) when startled. Other scavenging fish observed included the blue-hake Antimora rostrata, grenadiers (Macrourus spp.), skates, liparids and zoarcids.

scholarly journals Variability of the Antarctic Slope Current System in the Northwestern Weddell Sea

2017 ◽  
Vol 47 (12) ◽  
pp. 2977-2997 ◽  
Author(s):  
Marina Azaneu ◽  
Karen J. Heywood ◽  
Bastien Y. Queste ◽  
Andrew F. Thompson
Keyword(s):  
Current System ◽  
Water Layer ◽  
Bottom Layer ◽  
Weddell Sea ◽  
The South ◽  
Orkney Islands ◽  
Dense Water ◽  
South Orkney Islands ◽  
Antarctic Slope Current ◽  
The Antarctic

AbstractThe dense water outflow from the Antarctic continental shelf is closely associated with the strength and position of the Antarctic Slope Front. This study explores the short-term and spatial variability of the Antarctic Slope Front system and the mechanisms that regulate cross-slope exchange using highly temporally and spatially resolved measurements from three ocean gliders deployed in 2012. The 22 sections along the eastern Antarctic Peninsula and west of the South Orkney Islands are grouped regionally and composited by isobaths. There is consistency in the front position around the Powell Basin, varying mostly between the 500- and 800-m isobaths. In most of the study area the flow is bottom intensified. The along-slope transport of the Antarctic Slope Current (upper 1000 m) varies between 0.2 and 5.9 Sv (1 Sv ≡ 106 m3 s−1) and does not exhibit a regional pattern. The magnitude of the velocity field shows substantial variability, up to twice its mean value. Higher eddy kinetic energy (0.003 m2 s−2) is observed in sections with dense water, possibly because of baroclinic instabilities in the bottom layer. Distributions of potential vorticity show an increase toward the shelf along isopycnals and also in the dense water layer. Glider sections located west of the South Orkney Islands indicate a northward direction of the flow associated with the Weddell Front, which differs from previous estimates of the mean circulation. This study provides some of the first observational confirmation of the high-frequency variability associated with an active eddy field that has been suggested by recent numerical simulations in this region.

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