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

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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Spatial Structure and Intra-Annual Variability of Weddell Sea Front based on the Data of NOAA OISST Reanalysis

Ekologicheskaya bezopasnost pribrezhnoy i shel fovoy zon morya ◽

10.22449/2413-5577-2020-4-89-102 ◽

2020 ◽

Author(s):

Yu. V. Artamonov ◽

E. A. Skripaleva ◽

N. V. Nikolsky ◽

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Keyword(s):

Spatial Structure ◽

Antarctic Peninsula ◽

Time Lag ◽

Water Area ◽

Weddell Sea ◽

The South ◽

Orkney Islands ◽

Bransfield Strait ◽

South Orkney Islands ◽

The Antarctic

Based on the NOAA OISST reanalysis data, the spatial structure of the Weddell Sea Front in the climatic field of the sea surface temperature was analyzed and the seasonal variability of front’s characteristics was estimated. The spatial position of the frontal zone in the Weddell Sea was analyzed using distributions of the total horizontal temperature gradient. The characteristics of the front (the position of the gradients' extrema corresponding to the front, their magnitude and temperature on the front axis) were determined for each month on the profiles of meridional and zonal temperature gradients along meridians and parallels with a discreteness of 2.5° of longitude and 0.25° of latitude. It is shown that the interaction of Weddell Sea cold waters, which are transported by currents northward along the Antarctic Peninsula coasts, with the warmer waters of the eastern shelf of the Antarctic Peninsula and the Bransfield Strait surface water causes formation of two branches of the Weddell Sea Front. These branches round from a vast shelf at the Antarctic Peninsula tip and the Joinville archipelago the south and north and are traced further east along the boundaries of the bottom rise located approximately between 62.5S and 64.5S. To the south of the South Orkney Islands shelf, the two branches merge into one front, which follows to the east along the depth dump of the relative shallow between the South Orkney and South Sandwich Islands. In the seasonal cycle of the Weddell Sea Front intensity, a time lag was revealed of the front intensification period in the direction from west to east. In Bransfield Strait the front is most intense in February, between the Antarctic Peninsula tip and the South Orkney Islands – in March, east of the South Orkney Islands – in April. The branch of the Weddell Sea Front off the northeastern of the Antarctic Peninsula coasts intensifies in November – January, in the western part of the water area east of the James Ross and Snow Hill Islands – in January – February.

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The diet of the Antarctic fur seal Arctocephalus gazella at the South Orkney Islands in ten consecutive years

Polar Biology ◽

10.1007/s00300-015-1836-3 ◽

2016 ◽

Vol 39 (7) ◽

pp. 1197-1206 ◽

Cited By ~ 2

Author(s):

Ricardo Casaux ◽

Mariana Juares ◽

Alejandro Carlini ◽

Aldo Corbalán

Keyword(s):

Arctocephalus Gazella ◽

The South ◽

Antarctic Fur Seal ◽

Orkney Islands ◽

Fur Seal ◽

South Orkney Islands ◽

The Antarctic

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A new macroflora from the South Orkney Islands, Antarctica: evidence of an Early to Middle Jurassic age for the Powell Island Conglomerate

Antarctic Science ◽

10.1017/s0954102000000249 ◽

2000 ◽

Vol 12 (2) ◽

pp. 185-195 ◽

Cited By ~ 15

Author(s):

David J. Cantrill

Keyword(s):

Antarctic Peninsula ◽

Middle Jurassic ◽

Initial Phase ◽

The South ◽

Orkney Islands ◽

Continental Deposits ◽

Geological Evolution ◽

South Orkney Islands ◽

Break Up ◽

The Antarctic

A macroflora from John Peaks, Powell Island, contains Sagenopteris nilssoniana, Cladophlebis oblonga, Brachyphyllum sp., Elatocladus confertus, and Sphenopteris sp. The macroflora is best correlated with the Botany Bay Group flora, suggesting an Early to Middle Jurassic age for the Powell Island Conglomerate. This age supports new interpretations for the geological evolution of the Antarctic Peninsula that suggest the initial phase of Gondwana break-up was manifested as small rift grabens with continental deposits.

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The cryptostigmatid mite Halozetes belgicae (Michael) in the maritime Antarctic

Antarctic Science ◽

10.1017/s0954102091000093 ◽

1991 ◽

Vol 3 (1) ◽

pp. 53-59 ◽

Cited By ~ 4

Author(s):

L.B. Minto ◽

G.J. Shepherd ◽

M.B. Usher

Keyword(s):

South Shetland Islands ◽

Maritime Antarctic ◽

The South ◽

Macquarie Island ◽

Shetland Islands ◽

Orkney Islands ◽

South Orkney Islands ◽

South Sandwich Islands ◽

The Antarctic ◽

Morphometrical Study

Halozetes belgicae is distributed widely in the Subantarctic and maritime Antarctic, with subspecies described from Macquarie Island and the South Sandwich Islands. A morphometrical study, based largely on the development of the setae, indicates that the nominate subspecies is confined to the Antarctic Peninsula and its offshore islands (including the South Shetland Islands), whilst specimens from the South Orkney Islands are probably consubspecific with individuals on the South Sandwich Islands. In comparison with other studies of the Acari, the results strengthen the case for the recognition of a South Orkadian biogeographical zone.

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III.—Polychæta of the family Nereidæ, collected by the Scottish National Antarctic Expedition (1902–1904).

Transactions of the Royal Society of Edinburgh ◽

10.1017/s0080456800017269 ◽

1914 ◽

Vol 50 (1) ◽

pp. 41-48 ◽

Cited By ~ 6

Author(s):

L. N. G. Ramsay

Keyword(s):

Deep Water ◽

Falkland Islands ◽

The South ◽

Orkney Islands ◽

The Family ◽

Antarctic Expedition ◽

South Orkney Islands ◽

Chief Interest ◽

The Antarctic

The collection of Nereidæ brought home by the Scotia proves to be of considerable interest. As other expeditions have indicated, the family is but poorly represented in the antarctic or sub-antarctic regions; and although a large number of specimens were collected at the South Orkney Islands, these have all proved to belong to one species, N. kerguelensis M'Int. No nereids were obtained at any of the deep-water stations farther south—the family being decidedly littoral in its range.The chief interest, however, lies in the material collected so assiduously throughout the vessel's wanderings. Six other species were obtained, including one from the Falkland Islands, hitherto undescribed.

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Ocean currents as a potential dispersal pathway for Antarctica’s most persistent non-native terrestrial insect

Polar Biology ◽

10.1007/s00300-020-02792-2 ◽

2021 ◽

Author(s):

Jesamine C. Bartlett ◽

P. Convey ◽

K. A. Hughes ◽

S. E. Thorpe ◽

S. A. L. Hayward

Keyword(s):

Antarctic Peninsula ◽

Native Species ◽

Sea Water ◽

Ocean Current ◽

The South ◽

Near Surface ◽

Orkney Islands ◽

Signy Island ◽

South Orkney Islands ◽

The Antarctic

AbstractThe non-native midge Eretmoptera murphyi is Antarctica’s most persistent non-native insect and is known to impact the terrestrial ecosystems. It inhabits by considerably increasing litter turnover and availability of soil nutrients. The midge was introduced to Signy Island, South Orkney Islands, from its native South Georgia, and routes of dispersal to date have been aided by human activities, with little known about non-human-assisted methods of dispersal. This study is the first to determine the potential for dispersal of a terrestrial invertebrate species in Antarctica by combining physiological sea water tolerance data with quantitative assessments of ocean current journey times. Fourth instar larvae tolerated sea water submergence for up to 21 days, but submerged egg sacs had significantly reduced hatching success. Using near-surface drifter data, we conclude that ocean current dispersal from Signy Island would not present a risk of species transfer beyond the South Orkney Islands on the tested timescales. However, if E. murphyi were to be introduced to the South Shetlands Islands or Adelaide Island, which are located offshore of the Antarctic Peninsula, there would be a risk of successful oceanic dispersal to neighbouring islands and the Antarctic Peninsula mainland. This study emphasises the need for effective biosecurity measures and demonstrates the role that currently undocumented pathways may have in dispersing non-native species.

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The polar ship Scotia

Polar Record ◽

10.1017/s0032247405004237 ◽

2005 ◽

Vol 41 (2) ◽

pp. 131-140 ◽

Cited By ~ 2

Author(s):

Angus B. Erskine ◽

Kjell-G. Kjær

Keyword(s):

North Atlantic ◽

Weddell Sea ◽

Biological Research ◽

Orkney Islands ◽

Antarctic Expedition ◽

South Orkney Islands ◽

Antarctic Continent ◽

The Uk ◽

The Antarctic ◽

The Great War

The ship that the oceanographer Dr William Speirs Bruce used on the Scottish National Antarctic Expedition, 1902–04, was originally a sealer named Hekla, built in Norway in 1872. In 1889 the Norwegian skipper Ragnvald Knudsen explored the northeast coast of Greenland between latitudes 74° and 75°, and in 1891–92 the ship was used by the Danish naval officer, Lieutenant C. Ryder, to explore the inner recesses of Scoresby Sund, finally visiting Angmagssalik. In 1902, re-named Scotia and captained by Tam Robertson from Peterhead, she sailed to the Weddell Sea under the leadership of Bruce. The southern winter of 1903 was spent at Laurie Island in the South Orkney Islands, and in March–April 1904 the party discovered 150 miles of previously unknown coastline of the Antarctic continent, reaching a farthest south of 74°01′S, 22°00′W. An extensive programme of marine survey and biological research was carried out. Back in the UK, Bruce sold the ship, and she returned to sealing, based in Dundee until appointed to be the first international North Atlantic Ice Patrol ship after the tragedy of Titanic. The Great War caused her to become a freighter in the English Channel area until she caught fire and was burnt out on a sandbank in the Bristol Channel on 18 January 1916.

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Antarctic Place-names given by the Scottish National Antarctic Expedition, 1902–04

Polar Record ◽

10.1017/s0032247400041309 ◽

1943 ◽

Vol 4 (26) ◽

pp. 61-62 ◽

Cited By ~ 1

Author(s):

R. N. Rudmose Brown

Keyword(s):

Place Names ◽

The South ◽

Orkney Islands ◽

Antarctic Expedition ◽

South Orkney Islands ◽

Antarctic Continent ◽

Scientific Results ◽

The Antarctic

The following place-names in the South Orkney Islands and the Antarctic Continent were proposed by Dr W. S. Bruce; they were first published in the maps accompanying his paper in the Scottish Geographical Magazine for June 1905, and in the Reports on the Scientific Results of the Voyage of S.Y. Scotia, 1902–04 (Edinburgh, 1907–).

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