Correction to “Ocean tides in the Weddell Sea: New observations on the Filchner-Ronne and Larsen C ice shelves and model validation”

In the austral winter of 1979-80, a German Antarctic expedition was sent by ship to the Filchner and Ronne ice shelves in order to find a suitable site for the establishment of a permanent Antarctic station. During this expedition, investigations were carried out on sea ice in the Weddell Sea in order to evaluate the accessibility of the site for icebreaking ships which are intended to convey construction materials to the site and, later on, to supply the station annually.This paper covers the results of investigations on sea-ice conditions during the voyage along the ice shelves from Cape Fiske (at the base of the Antarctic Peninsula) to Atka Bay with emphasis on sea-ice conditions in the area about 100 km north-west of Berkner Island (Fig.1.). In addition to the drift conditions (speed, direction), a special feature of multi-year sea ice is described. The main part of the paper deals with mechanical properties such as flexural strength, uniaxial compressive strength and Young’s modulus of columnar-grained sea ice from the southern border of the Weddell Sea. Salinities and temperatures were measured over the depth of the ice and used for calculating the flexural strength and the Young’s modulus of the ice. The uniaxial compressive strength was investigated as a function of strain-rate, brine volume and temperature on a closed-loop testing machine on samples which were carried back from Antarctica to Hamburg.

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On the freshening of the northwestern Weddell Sea continental shelf

Ocean Science ◽

10.5194/os-7-305-2011 ◽

2011 ◽

Vol 7 (3) ◽

pp. 305-316 ◽

Cited By ~ 50

Author(s):

H. H. Hellmer ◽

O. Huhn ◽

D. Gomis ◽

R. Timmermann

Keyword(s):

Sea Ice ◽

Continental Shelf ◽

Weddell Sea ◽

Central Basin ◽

Thermal Front ◽

Late 20Th Century ◽

Ice Shelves ◽

Ice Retreat ◽

Reduced Salt ◽

Sea Ice Retreat

Abstract. We analyzed hydrographic data from the northwestern Weddell Sea continental shelf of the three austral winters 1989, 1997, and 2006 and two summers following the last winter cruise. During summer a thermal front exists at ~64° S separating cold southern waters from warm northern waters that have similar characteristics as the deep waters of the central basin of the Bransfield Strait. In winter, the whole continental shelf exhibits southern characteristics with high Neon (Ne) concentrations, indicating a significant input of glacial melt water. The comparison of the winter data from the shallow shelf off the tip of the Antarctic Peninsula, spanning a period of 17 yr, shows a salinity decrease of 0.09 for the whole water column, which has a residence time of <1 yr. We interpret this freshening as being caused by a combination of reduced salt input due to a southward sea ice retreat and higher precipitation during the late 20th century on the western Weddell Sea continental shelf. However, less salinification might also result from a delicate interplay between enhanced salt input due to sea ice formation in coastal areas formerly occupied by Larsen A and B ice shelves and increased Larsen C ice loss.

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Ice-shelf – ocean interactions at Fimbul Ice Shelf, Antarctica from oxygen isotope ratio measurements

Ocean Science ◽

10.5194/os-4-89-2008 ◽

2008 ◽

Vol 4 (1) ◽

pp. 89-98 ◽

Cited By ~ 14

Author(s):

M. R. Price ◽

K. J. Heywood ◽

K. W. Nicholls

Keyword(s):

Water Column ◽

Continental Slope ◽

Significant Contribution ◽

Weddell Sea ◽

Oxygen Isotope Ratio ◽

Ice Shelf ◽

Ice Shelves ◽

Greenwich Meridian ◽

Melt Water ◽

Ice Shelf Water

Abstract. Melt water from the floating ice shelves at the margins of the southeastern Weddell Sea makes a significant contribution to the fresh water budget of the region. In February 2005 a multi-institution team conducted an oceanographic campaign at Fimbul Ice Shelf on the Greenwich Meridian as part of the Autosub Under Ice programme. This included a mission of the autonomous submarine Autosub 25 km into the cavity beneath Fimbul Ice Shelf, and a number of ship-based hydrographic sections on the continental shelf and adjacent to the ice shelf front. The measurements reveal two significant sources of glacial melt water at Fimbul Ice Shelf: the main cavity under the ice shelf and an ice tongue, Trolltunga, that protrudes from the main ice front and out over the continental slope into deep water. Glacial melt water is concentrated in a 200 m thick Ice Shelf Water (ISW) layer below the base of the ice shelf at 150–200 m, with a maximum glacial melt concentration of up to 1.16%. Some glacial melt is found throughout the water column, and much of this is from sources other than Fimbul Ice Shelf. However, at least 0.2% of the water in the ISW layer cannot be accounted for by other processes and must have been contributed by the ice shelf. Just downstream of Fimbul Ice Shelf we observe locally created ISW mixing out across the continental slope. The ISW formed here is much less dense than that formed in the southwest Weddell Sea, and will ultimately contribute a freshening (and reduction in δ18O) to the upper 100–150 m of the water column in the southeast Weddell Sea.

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Evolution of under Water Sides of Ice Shelves and Icebergs

Annals of Glaciology ◽

10.1017/s0260305500000574 ◽

1987 ◽

Vol 9 ◽

pp. 176-182 ◽

Cited By ~ 5

Author(s):

Olav Orheim

Keyword(s):

Vertical Wall ◽

Weddell Sea ◽

Mature Stage ◽

List Type ◽

Near Surface ◽

Ice Shelves ◽

Side Scan Sonar ◽

Water Line ◽

Formative Stage ◽

The Face

A systematic programme of side-scan sonar and plumb- line soundings was carried out in the Weddell Sea area in 1985 to measure the under-water sides of ice shelves and icebergs. From these observations the following model is suggested for the evolution of the ice front:(1)Initial stage: fracturing of the ice shelves takes place along smooth, curvi-linear segments with vertical faces.(2)Formative stage: the freshly formed vertical face is eroded both by wave and swell action around the water line, by small calvings from the undercut, overhanging subaerial face, and by submarine melting. The melting has a minimum at 50–100 m depth, and increases with depth to a rate of around 10 m a−1at 200 m, This is about twice the rate of erosion at the water line. The variation in melting with depth results from a combination of summer melting by near-surface water, and year-round melting by water masses that are increasingly warmer than the pressure melting-point with depth.(3)Mature stage: this stage is reached after a few years of exposure. The backward erosion of the face leads to a shape with a prominent under-water “nose” with a maximum projection to more than 50 m at 50–100 m depth. The ramp above this slopes upwards to meet the vertical wall about 5 m below the water line. The ice below the nose is melted back beyond the above-water face. There is no net buoyancy and ice shelves at this mature stage are generallynotup-warped at the front.

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Sea-Ice Investigations In The Weddell Sea During The German Antarctic Expedition 1979-80

Annals of Glaciology ◽

10.3189/s0260305500005553 ◽

1983 ◽

Vol 4 ◽

pp. 246-252

Author(s):

Joachim Schwarz

Keyword(s):

Compressive Strength ◽

Flexural Strength ◽

Sea Ice ◽

Young’S Modulus ◽

Uniaxial Compressive Strength ◽

Young's Modulus ◽

Weddell Sea ◽

Ice Shelves ◽

Antarctic Expedition ◽

Ice Conditions

In the austral winter of 1979-80, a German Antarctic expedition was sent by ship to the Filchner and Ronne ice shelves in order to find a suitable site for the establishment of a permanent Antarctic station. During this expedition, investigations were carried out on sea ice in the Weddell Sea in order to evaluate the accessibility of the site for icebreaking ships which are intended to convey construction materials to the site and, later on, to supply the station annually.This paper covers the results of investigations on sea-ice conditions during the voyage along the ice shelves from Cape Fiske (at the base of the Antarctic Peninsula) to Atka Bay with emphasis on sea-ice conditions in the area about 100 km north-west of Berkner Island (Fig.1.). In addition to the drift conditions (speed, direction), a special feature of multi-year sea ice is described. The main part of the paper deals with mechanical properties such as flexural strength, uniaxial compressive strength and Young’s modulus of columnar-grained sea ice from the southern border of the Weddell Sea. Salinities and temperatures were measured over the depth of the ice and used for calculating the flexural strength and the Young’s modulus of the ice. The uniaxial compressive strength was investigated as a function of strain-rate, brine volume and temperature on a closed-loop testing machine on samples which were carried back from Antarctica to Hamburg.

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Submarine landforms on the Weddell Sea shelf imaged at high resolution using AUVs

10.5194/egusphere-egu2020-1603 ◽

2020 ◽

Author(s):

Julian Dowdeswell ◽

Christine Batchelor ◽

Sasha Montelli ◽

Dag Ottesen ◽

Evelyn Dowdeswell ◽

...

Keyword(s):

High Resolution ◽

Autonomous Underwater Vehicles ◽

Horizontal Resolution ◽

Weddell Sea ◽

Ice Shelves ◽

Glacial Landform ◽

Glacial Landforms ◽

The Antarctic ◽

The Last Glacial Maximum ◽

The Last Glacial

Multibeam echo-sounders were deployed from Autonomous Underwater Vehicles (AUVs) flying close to the seafloor of the Weddell Sea shelf in order to investiagte the glacial landforms there with a view to understanding processes and patterns associated with deglaciation from the Last Glacial Maximum on the eastern side of the Antarctic Peninsula. A horizontal resolution of 0.5 m (using conventional mulitbeam systems), and in some cases 0.05 m (using interferometric multibeam equipment), allowed delicate seafloor landforms to be mapped in several areas of the shelf beyond the Larsen C and former Larsen A and B ice shelves. A number of glacial landform assemblages were observed, including suites of delicate ridges associated with grounding-zone wedges and the grounding of icebergs on the shelf. These landforms are probably related to the action of tides moving the ice up and down through a series of tidal cycles. At the highest spatial resolution, individual dropstones derived from rain-out during the melting of floating ice were imaged clearly. Imaging the seafloor at such high resolution allows both very detailed descriptions of submarine landform morphology and also the complexity of such landforms and landform assemblages to be better understood, aiding the interpretation of the glacial and related processes that led to their formation.

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Recent glacial advance in the western Weddell Sea Sector driven by anomalous sea ice circulation

10.5194/egusphere-egu2020-7801 ◽

2020 ◽

Author(s):

Frazer Christie ◽

Toby Benham ◽

Julian Dowdeswell

Keyword(s):

Sea Ice ◽

Antarctic Peninsula ◽

Ice Sheet ◽

Weddell Sea ◽

Landsat 8 ◽

Ice Shelf ◽

Total Contribution ◽

Antarctic Ice Sheet ◽

Ice Shelves ◽

The Antarctic

The Antarctic Peninsula is one of the most rapidly warming regions on Earth. There, the recent destabilization of the Larsen A and B ice shelves has been directly attributed to this warming, in concert with anomalous changes in ocean circulation. Having rapidly accelerated and retreated following the demise of Larsen A and B, the inland glaciers once feeding these ice shelves now form a significant proportion of Antarctica&#8217;s total contribution to global sea-level rise, and have become an exemplar for the fate of the wider Antarctic Ice Sheet under a changing climate. Together with other indicators of glaciological instability observable from satellites, abrupt pre-collapse changes in ice shelf terminus position are believed to have presaged the imminent disintegration of Larsen A and B, which necessitates the need for routine, close observation of this sector in order to accurately forecast the future stability of the Antarctic Peninsula Ice Sheet. To date, however, detailed records of ice terminus position along this region of Antarctica only span the observational period c.1950 to 2008, despite several significant changes to the coastline over the last decade, including the calving of giant iceberg A-68a from Larsen C Ice Shelf in 2017.Here, we present high-resolution, annual records of ice terminus change along the entire western Weddell Sea Sector, extending southwards from the former Larsen A Ice Shelf on the eastern Antarctic Peninsula to the periphery of Filchner Ice Shelf. Terminus positions were recovered primarily from Sentinel-1a/b, TerraSAR-X and ALOS-PALSAR SAR imagery acquired over the period 2009-2019, and were supplemented with Sentinel-2a/b, Landsat 7 ETM+ and Landsat 8 OLI optical imagery across regions of complex terrain.Confounding Antarctic Ice Sheet-wide trends of increased glacial recession and mass loss over the long-term satellite era, we detect glaciological advance along 83% of the ice shelves fringing the eastern Antarctic Peninsula between 2009 and 2019. With the exception of SCAR Inlet, where the advance of its terminus position is attributable to long-lasting ice dynamical processes following the disintegration of Larsen B, this phenomenon lies in close agreement with recent observations of unchanged or arrested rates of ice flow and thinning along the coastline. Global climate reanalysis and satellite passive-microwave records reveal that this spatially homogenous advance can be attributed to an enhanced buttressing effect imparted on the eastern Antarctic Peninsula&#8217;s ice shelves, governed primarily by regional-scale increases in the delivery and concentration of sea ice proximal to the coastline.

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Modelling the impact of ocean warming on melting and water masses of ice shelves in the Eastern Weddell Sea

Ocean Dynamics ◽

10.1007/s10236-010-0262-x ◽

2010 ◽

Vol 60 (3) ◽

pp. 479-489 ◽

Cited By ~ 7

Author(s):

Malte Thoma ◽

Klaus Grosfeld ◽

Keith Makinson ◽

Manfred A. Lange

Keyword(s):

Ocean Warming ◽

Weddell Sea ◽

Water Masses ◽

Ice Shelves ◽

The Impact ◽

Eastern Weddell Sea

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Bathymetry and acoustic facies beneath the former Larsen-A and Prince Gustav ice shelves, north-west Weddell Sea

Antarctic Science ◽

10.1017/s095410200100044x ◽

2001 ◽

Vol 13 (3) ◽

pp. 312-322 ◽

Cited By ~ 31

Author(s):

Carol J. Pudsey ◽

Jeffrey Evans ◽

Eugene W. Domack ◽

Peter Morris ◽

Rodolfo A. Del Valle

Keyword(s):

Continental Shelf ◽

Weddell Sea ◽

Shelf Edge ◽

Ice Shelf ◽

Ice Shelves ◽

North West ◽

Preliminary Results ◽

The Past ◽

Acoustic Facies ◽

Marine Mud

We present preliminary results of the first detailied surveys of the former Larsen-A Ice Shelf, Larsen Inlet and southern Prince Gustav Channel, where disintegration of small ice shelves in the past ten years has exposed the seafloor. Glacial troughs in the Larsen-A area, Larsen Inlet and Prince Gustav Channel reach 900–1100 m depth and have hummocky floors. Farther south-east, the continental shelf is shallower (400–500 m) and its surface is fluted to smooth, with the density of iceberg furrowing increasing towards the shelf edge. Acoustic profiles show a drape of transparent sediment 4–8 m thick in Prince Gustav Channel, thinning southwards. In cores, this drape corresponds to diatom-bearing marine and glacial-marine mud. In the Larsen-A area and Larsen Inlet, acoustically opaque sediment includes proximal ice shelf glaciomarine gravelly and sandy muds, and firm to stiff diamicts probably deposited subglacilly. These are overlain by thin (up to 1.3 m) glaciomarine muds, locally with distinctive diatom ooze laminae.

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