Transfer faults in the western Ross Sea: new evidence from the McMurdo Sound/Ross Ice Shelf aeromagnetic survey (GANOVEX VI)

1994 ◽  
Vol 6 (3) ◽  
pp. 359-364 ◽  
Author(s):  
D. Damaske ◽  
J. Behrendt ◽  
A. McCafferty ◽  
R. Saltus ◽  
U. Meyer
Keyword(s):  
Ross Sea ◽  
Rift System ◽  
Ice Shelf ◽  
Aeromagnetic Survey ◽  
Southern Boundary ◽  
Ross Ice Shelf ◽  
The North ◽  
West Antarctic ◽  
Transfer Faults ◽  
Western Ross Sea

Aeromagnetic data collected on the GANOVEX IV and GANOVEX VI expeditions are combined in this report to give a synoptic view of the western Ross Sea, Antarctica. The addition of the new GANOVEX VI data allows the identification of the southern boundary of the “Ross Sea Unit” — a magnetic unit containing rift-fabric anomalies of the West Antarctic rift system in the Victoria Land basin. Although this boundary has a similar WSW–ENE orientation to the northern boundary, as identified in the GANOVEX IV survey, the newly identified southern magnetic unit (called the “Ross Island and Ice Shelf Edge Unit”) includes evidence of the S–N rift-fabric that is not found in the north, i.e. the rift-fabric continues farther south. The linear boundaries themselves are interpreted as transfer faults as proposed by previous workers for the tectonic development of the Ross Sea area.

Effects of giant icebergs on two emperor penguin colonies in the Ross Sea, Antarctica

2007 ◽  
Vol 19 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Gerald L. Kooyman ◽  
David G. Ainley ◽  
Grant Ballard ◽  
Paul J. Ponganis
Keyword(s):  
Ross Sea ◽  
Emperor Penguin ◽  
Ice Shelf ◽  
West Antarctic Ice Sheet ◽  
North West ◽  
Ross Ice Shelf ◽  
The North ◽  
West Antarctic ◽  
South West ◽  
Wintering Areas

The arrival in January 2001 in the south-west Ross Sea of two giant icebergs, C16 and B15A, subsequently had dramatic affects on two emperor penguin colonies. B15A collided with the north-west tongue of the Ross Ice Shelf at Cape Crozier, Ross Island, in the following months and destroyed the penguins' nesting habitat. The colony totally failed in 2001, and years after, with the icebergs still in place, exhibited reduced production that ranged from 0 to 40% of the 1201 chicks produced in 2000. At Beaufort Island, 70 km NW of Crozier, chick production declined to 6% of the 2000 count by 2004. Collisions with the Ross Ice Shelf at Cape Crozier caused incubating adults to be crushed, trapped in ravines, or to abandon the colony and, since 2001, to occupy poorer habitat. The icebergs separated Beaufort Island from the Ross Sea Polynya, formerly an easy route to feeding and wintering areas. This episode has provided a glimpse of events which have probably occurred infrequently since the West Antarctic Ice Sheet began to retreat 12 000 years ago. The results allow assessment of recovery rates for one colony decimated by both adult and chick mortality, and the other colony by adult abandonment and chick mortality.

Modelling the ocean circulation beneath the Ross Ice Shelf

2003 ◽  
Vol 15 (1) ◽  
pp. 13-23 ◽  
Author(s):  
DAVID M. HOLLAND ◽  
STANLEY S. JACOBS ◽  
ADRIAN JENKINS
Keyword(s):  
Ocean Circulation ◽  
General Circulation ◽  
Ross Sea ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Shelf Water ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
The North ◽  
Ice Shelf Water

We applied a modified version of the Miami isopycnic coordinate ocean general circulation model (MICOM) to the ocean cavity beneath the Ross Ice Shelf to investigate the circulation of ocean waters in the sub-ice shelf cavity, along with the melting and freezing regimes at the base of the ice shelf. Model passive tracers are utilized to highlight the pathways of waters entering and exiting the cavity, and output is compared with data taken in the cavity and along the ice shelf front. High Salinity Shelf Water on the western Ross Sea continental shelf flows into the cavity along the sea floor and is transformed into Ice Shelf Water upon contact with the ice shelf base. Ice Shelf Water flows out of the cavity mainly around 180°, but also further east and on the western side of McMurdo Sound, as observed. Active ventilation of the region near the ice shelf front is forced by seasonal variations in the density structure of the water column to the north, driving rapid melting. Circulation in the more isolated interior is weaker, leading to melting at deeper ice and refreezing beneath shallower ice. Net melting over the whole ice shelf base is lower than other estimates, but is likely to increase as additional forcings are added to the model.

scholarly journals An Analysis of Low-Level Jets in the Greater Ross Ice Shelf Region Based on Numerical Simulations

2008 ◽  
Vol 136 (11) ◽  
pp. 4188-4205 ◽  
Author(s):  
Mark W. Seefeldt ◽  
John J. Cassano
Keyword(s):  
Wind Speed ◽  
Ross Sea ◽  
Ice Shelf ◽  
Self Organizing Maps ◽  
Low Level ◽  
Ross Ice Shelf ◽  
The North ◽  
Low Level Jets ◽  
Shelf Region ◽  
Strong Seasonality

Abstract An analysis of the presence and location of low-level jets (LLJs) across the Ross Ice Shelf region in Antarctica is presented based on the analysis of archived output from the real-time Antarctic Mesoscale Prediction System (AMPS). The method of self-organizing maps (SOMs) is used to objectively identify different patterns in column-averaged wind speed (over the approximately lowest 1200 m of the atmosphere) as an identifier to the location of LLJs. The results indicate three primary LLJs in the region. The largest and most dominant LLJ is along the Transantarctic Mountains by the Siple Coast and the southern end of the Ross Ice Shelf. The second LLJ extends from the base of Byrd Glacier and curves to the north passing by the eastern extremes of Ross Island. The third LLJ extends from the base of Reeves Glacier and curves to the north across the western Ross Sea. A strong seasonality is observed in the frequency and intensity of the LLJs with the highest values for wind speed and the size of the LLJ at a maximum during the winter and spring months.

scholarly journals Late Pleistocene interactions of East and West Antarctic Ice-flow Regimes: evidence from the McMurdo Ice Shelf

1996 ◽  
Vol 42 (142) ◽  
pp. 486-500 ◽  
Author(s):  
Thomas B. Kellogg ◽  
Terry Hughes ◽  
Davida E. Kellogg
Keyword(s):  
Ross Sea ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Ice Streams ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
West Antarctic ◽  
Grounding Line ◽  
Glacier Ice ◽  
East And West

AbstractWe present new interpretations of deglaciation in McMurdo Sound and the western Ross Sea, with observationally based reconstructions of interactions between East and West Antarctic ice at the last glacial maximum (LGM), 16000, 12000, 8000 and 4000 BP. At the LGM, East Antarctic ice from Mulock Glacier split; one branch turned westward south of Ross Island but the other branch rounded Ross Island before flowing southwest into McMurdo Sound. This flow regime, constrained by an ice saddle north of Ross Island, is consistent with the reconstruction of Stuiver and others (1981a). After the LGM, grounding-line retreat was most rapid in areas with greatest water depth, especially along the Victoria Land coast. By 12000 BP, the ice-now regime in McMurdo Sound changed to through-flowing Mulock Glacier ice, with lesser contributions from Koettlitz, Blue and Ferrar Glaciers, because the former ice saddle north of Ross Island was replaced by a dome. The modern flew regime was established ∼4000 BP. Ice derived from high elevations on the Polar Plateau but now stranded on the McMurdo Ice Shelf, and the pattern of the Transantarctic Mountains erratics support our reconstructions of Mulock Glacier ice rounding Minna Bluff but with all ice from Skelton Glacier ablating south of the bluff. They are inconsistent with Drewry’s (1979) LGM reconstruction that includes Skelton Glacier ice in the McMurdo-Sound through-flow. Drewry’s (1979) model closely approximates our results for 12000-4000 BP. Ice-sheet modeling holds promise for determining whether deglaciation proceeded by grounding-line retreat of an ice sheet that was largely stagnant, because it never approached equilibrium flowline profiles after the Ross Ice Shelf grounded, or of a dynamic ice sheet with flowline profiles kept low by active ice streams that extended northward from present-day outlet glaciers after the Ross Ice Shelf grounded.

scholarly journals Widespread collapse of the Ross Ice Shelf during the late Holocene

2016 ◽  
Vol 113 (9) ◽  
pp. 2354-2359 ◽  
Author(s):  
Yusuke Yokoyama ◽  
John B. Anderson ◽  
Masako Yamane ◽  
Lauren M. Simkins ◽  
Yosuke Miyairi ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Late Holocene ◽  
Ross Sea ◽  
Sediment Cores ◽  
Ocean Modeling ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Ross Ice Shelf ◽  
Grounding Line ◽  
Western Ross Sea

The stability of modern ice shelves is threatened by atmospheric and oceanic warming. The geologic record of formerly glaciated continental shelves provides a window into the past of how ice shelves responded to a warming climate. Fields of deep (−560 m), linear iceberg furrows on the outer, western Ross Sea continental shelf record an early post-Last Glacial Maximum episode of ice-shelf collapse that was followed by continuous retreat of the grounding line for ∼200 km. Runaway grounding line conditions culminated once the ice became pinned on shallow banks in the western Ross Sea. This early episode of ice-shelf collapse is not observed in the eastern Ross Sea, where more episodic grounding line retreat took place. More widespread (∼280,000 km2) retreat of the ancestral Ross Ice Shelf occurred during the late Holocene. This event is recorded in sediment cores by a shift from terrigenous glacimarine mud to diatomaceous open-marine sediment as well as an increase in radiogenic beryllium (10Be) concentrations. The timing of ice-shelf breakup is constrained by compound specific radiocarbon ages, the first application of this technique systematically applied to Antarctic marine sediments. Breakup initiated around 5 ka, with the ice shelf reaching its current configuration ∼1.5 ka. In the eastern Ross Sea, the ice shelf retreated up to 100 km in about a thousand years. Three-dimensional thermodynamic ice-shelf/ocean modeling results and comparison with ice-core records indicate that ice-shelf breakup resulted from combined atmospheric warming and warm ocean currents impinging onto the continental shelf.

scholarly journals Late Pleistocene interactions of East and West Antarctic Ice-flow Regimes: evidence from the McMurdo Ice Shelf

1996 ◽  
Vol 42 (142) ◽  
pp. 486-500
Author(s):  
Thomas B. Kellogg ◽  
Terry Hughes ◽  
Davida E. Kellogg
Keyword(s):  
Ross Sea ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Ice Streams ◽  
Mcmurdo Sound ◽  
Ross Ice Shelf ◽  
West Antarctic ◽  
Grounding Line ◽  
Glacier Ice ◽  
East And West

AbstractWe present new interpretations of deglaciation in McMurdo Sound and the western Ross Sea, with observationally based reconstructions of interactions between East and West Antarctic ice at the last glacial maximum (LGM), 16000, 12000, 8000 and 4000 BP. At the LGM, East Antarctic ice from Mulock Glacier split; one branch turned westward south of Ross Island but the other branch rounded Ross Island before flowing southwest into McMurdo Sound. This flow regime, constrained by an ice saddle north of Ross Island, is consistent with the reconstruction of Stuiver and others (1981a). After the LGM, grounding-line retreat was most rapid in areas with greatest water depth, especially along the Victoria Land coast. By 12000 BP, the ice-now regime in McMurdo Sound changed to through-flowing Mulock Glacier ice, with lesser contributions from Koettlitz, Blue and Ferrar Glaciers, because the former ice saddle north of Ross Island was replaced by a dome. The modern flew regime was established ∼4000 BP. Ice derived from high elevations on the Polar Plateau but now stranded on the McMurdo Ice Shelf, and the pattern of the Transantarctic Mountains erratics support our reconstructions of Mulock Glacier ice rounding Minna Bluff but with all ice from Skelton Glacier ablating south of the bluff. They are inconsistent with Drewry’s (1979) LGM reconstruction that includes Skelton Glacier ice in the McMurdo-Sound through-flow. Drewry’s (1979) model closely approximates our results for 12000-4000 BP. Ice-sheet modeling holds promise for determining whether deglaciation proceeded by grounding-line retreat of an ice sheet that was largely stagnant, because it never approached equilibrium flowline profiles after the Ross Ice Shelf grounded, or of a dynamic ice sheet with flowline profiles kept low by active ice streams that extended northward from present-day outlet glaciers after the Ross Ice Shelf grounded.

scholarly journals Environmental and Oceanographic Conditions at the Continental Margin of the Central Basin, Northwestern Ross Sea (Antarctica) Since the Last Glacial Maximum

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 155
Author(s):  
Fiorenza Torricella ◽  
Romana Melis ◽  
Elisa Malinverno ◽  
Giorgio Fontolan ◽  
Mauro Bussi ◽  
...  
Keyword(s):  
Continental Margin ◽  
Ross Sea ◽  
Time Interval ◽  
Central Basin ◽  
Ice Shelf ◽  
Last Glacial ◽  
Ross Ice Shelf ◽  
Sedimentary Sequences ◽  
Ash Layer ◽  
The Last Glacial

The continental margin is a key area for studying the sedimentary processes related to the advance and retreat of the Ross Ice Shelf (Antarctica); nevertheless, much remains to be investigated. The aim of this study is to increase the knowledge of the last glacial/deglacial dynamics in the Central Basin slope–basin system using a multidisciplinary approach, including integrated sedimentological, micropaleontological and tephrochronological information. The analyses carried out on three box cores highlighted sedimentary sequences characterised by tree stratigraphic units. Collected sediments represent a time interval from 24 ka Before Present (BP) to the present time. Grain size clustering and data on the sortable silt component, together with diatom, silicoflagellate and foraminifera assemblages indicate the influence of the ice shelf calving zone (Unit 1, 24–17 ka BP), progressive receding due to Circumpolar Deep Water inflow (Unit 2, 17–10.2 ka BP) and (Unit 3, 10.2 ka BP–present) the establishment of seasonal sea ice with a strengthening of bottom currents. The dominant and persistent process is a sedimentation controlled by contour currents, which tend to modulate intensity in time and space. A primary volcanic ash layer dated back at around 22 ka BP is correlated with the explosive activity of Mount Rittmann.

New determinations of tides on the north-western Ross Ice Shelf

2020 ◽  
pp. 1-14
Author(s):  
Richard D. Ray ◽  
Kristine M. Larson ◽  
Bruce J. Haines
Keyword(s):  
Time Series ◽  
Tide Gauge ◽  
High Rate ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
The North ◽  
Global Positioning ◽  
North Western

Abstract New determinations of ocean tides are extracted from high-rate Global Positioning System (GPS) solutions at nine stations sitting on the Ross Ice Shelf. Five are multi-year time series. Three older time series are only 2–3 weeks long. These are not ideal, but they are still useful because they provide the only in situ tide observations in that sector of the ice shelf. The long tide-gauge observations from Scott Base and Cape Roberts are also reanalysed. They allow determination of some previously neglected tidal phenomena in this region, such as third-degree tides, and they provide context for analysis of the shorter datasets. The semidiurnal tides are small at all sites, yet M2 undergoes a clear seasonal cycle, which was first noted by Sir George Darwin while studying measurements from the Discovery expedition. Darwin saw a much larger modulation than we observe, and we consider possible explanations - instrumental or climatic - for this difference.

scholarly journals A Cross-Sectional Model for West Antarctica

1984 ◽  
Vol 5 ◽  
pp. 95-99 ◽  
Author(s):  
B. J. McInnes ◽  
W. F. Budd
Keyword(s):  
Ross Sea ◽  
Dynamic State ◽  
Ice Thickness ◽  
Cross Sectional ◽  
West Antarctic Ice Sheet ◽  
Ross Ice Shelf ◽  
West Antarctic ◽  
Mass Fluxes ◽  
Ice Stream B ◽  
The One

The dynamic state of the West Antarctic ice sheet has been termed the grand problem of glaciology. An attempt is presented to assess it by simulating the observed ice thickness and ice velocities along a cross-section from ice stream B (Ross Sea) to Pine Island Glacier (Pine Island Bay) with a numerical model developed from the one described by Budd and McInnes (1978). A kinematic analysis with topographical and regime data from various sources shows the mass fluxes observed near the grounding line of the Ross Ice Shelf to be of the order expected for steady-state balance. Deformation of the ice accounts for only a small fraction of the observed flow there. Simulations (to be described in detail elsewhere) with the Budd/McInnes surging mechanism can approximate the existing ice thickness as a post-surge feature but fail to reproduce the high balance velocities. Both these velocities and the existing ice-thickness profile are simulated successfully as a state of steady sliding, with parameterizations involving the ice thickness above that corresponding to buoyancy and realistically assumed longitudinal strain-rates. A range of results is presented to illustrate the sensitivity of the simulation to changes in various parameters.

scholarly journals Electromagnetic Sounding of Bottom Crevasses on the Ross Ice Shelf, Antarctica

1979 ◽  
Vol 24 (90) ◽  
pp. 321-330 ◽  
Author(s):  
Kenneth C. Jezek ◽  
Charles R. Bentley ◽  
John W. Clough
Keyword(s):  
Flow Direction ◽  
Ice Shelf ◽  
Electromagnetic Sounding ◽  
West Antarctic Ice Sheet ◽  
North West ◽  
Ross Ice Shelf ◽  
North East ◽  
West Antarctic ◽  
Ice Stream B ◽  
Folded Dipole

AbstractDuring the 1976—77 season of the Ross Ice Shelf Geophysical and Glaciological Survey, a series of vertical electromagnetic sounding profiles of subsurface features was completed at station J-9. The survey comprised three five-kilometer north-west-south-east profiles separated by one kilometer and six two-kilometer north-east-south-west profiles, and was carried out on the surface using 35 MHz and 50 MHz radar systems. Folded-dipole antennae were used and oriented to detect reflectors both along and perpendicular to the profile path. This was done to facilitate the interpretation of the data, which indicated a complex system of bottom crevasses. Measurements of the positions, heights, and shapes of these crevasses showed at least two sets of crevasses varying in both strike and size. The larger crevasses, about 120 m high and oriented more or less normal to the flow direction, are probably associated with the movement of ice stream B across the grounding line between the West Antarctic ice sheet and the Ross Ice Shelf. A satisfactory explanation for the secondary set of crevasses, about 60 m high and forming an angle of 60° ±10° with the first set, has not yet been found.

Sign in / Sign up

Export Citation Format

Share Document