scholarly journals The effect of basal melting of the Shirase Glacier Tongue on the CO 2 system in Lützow‐Holm Bay, East Antarctica

2021 ◽  
Author(s):  
Masaaki Kiuchi ◽  
Daiki Nomura ◽  
Daisuke Hirano ◽  
Takeshi Tamura ◽  
Gen Hashida ◽  
...  
Keyword(s):  
East Antarctica ◽  
Glacier Tongue ◽  
Basal Melting

scholarly journals New velocity map and mass-balance estimate of Mertz Glacier, East Antarctica, derived from Landsat sequential imagery

2003 ◽  
Vol 49 (167) ◽  
pp. 503-511 ◽  
Author(s):  
Etienne Berthier ◽  
Bruce Raup ◽  
Ted Scambos
Keyword(s):  
Velocity Field ◽  
Drainage Basin ◽  
Flow Speed ◽  
East Antarctica ◽  
Landsat Images ◽  
Mean Velocity ◽  
Speed Increase ◽  
Glacier System ◽  
Show Evidence ◽  
Basal Melting

AbstractAutomatic feature tracking on two Landsat images (acquired inJanuary 2000 and December 2001) generates a complete and accurate velocity field of Mertz Glacier, East Antarctica. This velocity field shows two main tributaries to the ice stream. Between the tributaries, a likely obstruction feature in the bedrock results in a slow-down of the flow. A third Landsat image, acquired in 1989 and combined with the 2000 image, permits the determination of the glacier mean velocity during the 1990s. Although some parts of the Mertz Glacier system show evidence of slight speed increase, we conclude that the Mertz flow speed is constant within our uncertainty (35 m a−1). Using this complete velocity field, new estimates of the ice discharge flux, 17.8 km3 a−1 (16.4 Gt a−1), and of the basal melting of the tongue, 11 m a−1 of ice, are given. Our results lead to an apparent imbalance of the drainage basin (ice discharge 3.5 km3 a−1 lower than the accumulation). Considering previous studies in the Mertz Glacier area, we then discuss the uncertainty of this imbalance and the problems with accumulation mapping for this region.

scholarly journals Thermohaline structure and circulation beneath the Langhovde Glacier ice shelf in East Antarctica

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Masahiro Minowa ◽  
Shin Sugiyama ◽  
Masato Ito ◽  
Shiori Yamane ◽  
Shigeru Aoki
Keyword(s):  
Freezing Point ◽  
East Antarctica ◽  
Ice Shelf ◽  
Rate Estimate ◽  
Ice Shelves ◽  
Plume Water ◽  
Warm Deep Water ◽  
Glacier Ice ◽  
Basal Melting

AbstractBasal melting of ice shelves is considered to be the principal driver of recent ice mass loss in Antarctica. Nevertheless, in-situ oceanic data covering the extensive areas of a subshelf cavity are sparse. Here we show comprehensive structures of temperature, salinity and current measured in January 2018 through four boreholes drilled at a ~3-km-long ice shelf of Langhovde Glacier in East Antarctica. The measurements were performed in 302–12 m-thick ocean cavity beneath 234–412 m-thick ice shelf. The data indicate that Modified Warm Deep Water is transported into the grounding zone beneath a stratified buoyant plume. Water at the ice-ocean interface was warmer than the in-situ freezing point by 0.65–0.95°C, leading to a mean basal melt rate estimate of 1.42 m a−1. Our measurements indicate the existence of a density-driven water circulation in the cavity beneath the ice shelf of Langhovde Glacier, similar to that proposed for warm-ocean cavities of larger Antarctic ice shelves.

scholarly journals Strong ice-ocean interaction beneath Shirase Glacier Tongue in East Antarctica

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Daisuke Hirano ◽  
Takeshi Tamura ◽  
Kazuya Kusahara ◽  
Kay I. Ohshima ◽  
Keith W. Nicholls ◽  
...  
Keyword(s):  
East Antarctica ◽  
Glacier Tongue

scholarly journals Brief communication: Impacts of a developing polynya off Commonwealth Bay, East Antarctica, triggered by grounding of iceberg B09B

2016 ◽  
Vol 10 (6) ◽  
pp. 2603-2609 ◽  
Author(s):  
Christopher J. Fogwill ◽  
Erik van Sebille ◽  
Eva A. Cougnon ◽  
Chris S. M. Turney ◽  
Steve R. Rintoul ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Bottom Water ◽  
High Salinity ◽  
Satellite Observations ◽  
East Antarctica ◽  
Shelf Water ◽  
Antarctic Bottom Water ◽  
Glacier Tongue

Abstract. The dramatic calving of the Mertz Glacier tongue in 2010, precipitated by the movement of iceberg B09B, reshaped the oceanographic regime across the Mertz Polynya and Commonwealth Bay, regions where high-salinity shelf water (HSSW) – the precursor to Antarctic bottom water (AABW) – is formed. Here we present post-calving observations that suggest that this reconfiguration and subsequent grounding of B09B have driven the development of a new polynya and associated HSSW production off Commonwealth Bay. Supported by satellite observations and modelling, our findings demonstrate how local icescape changes may impact the formation of HSSW, with potential implications for large-scale ocean circulation.

scholarly journals Interpretation of basal ice conditions from radio-echo soundings in the eastern Heimefrontfjella and the southern Vestfjella mountain ranges, East Antarctica

1993 ◽  
Vol 17 ◽  
pp. 312-316 ◽  
Author(s):  
Per Holmlund
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Vertical Component ◽  
Ablation Rate ◽  
East Antarctica ◽  
Radio Waves ◽  
Mountain Areas ◽  
Surface Mass ◽  
Ice Conditions ◽  
Basal Melting

Differences in radio-echoes received from the base of the ice sheet covering two different mountain areas in Dronning Maud Land, East Antarctica, are herein interpreted as differences in the physical properties in the ice and differences in basal conditions. An abnormally strong signal can be caused either by unusually little absorption of radio waves within the ice or by water at the base of the glacier. One of the areas studied is totally covered by a 400–1400 m thick ice sheet. The altitude of the surface is about 2800 m a.s.l. The second area is a nunatak area situated relatively closer to the coast. The ice thickness in the valleys is about 500 m and the altitude of the surface is about 400 m. The annual mean surface temperature for the areas is about −30° and −17°C respectively. In both cases ice depths are moderate and flow rates low, and it is thus probable that the ice is frozen to the bed. However, in the colder locality I believe the strong echo is caused by low or negligible rate of mass flux. In the lower area strong bottom echoes are believed to be a cause of negative mass balance at the surface of the blue ice areas. The negative surface mass balance reverses the vertical component of ice flow and it also changes the temperature distribution within the ice. Basal melting conditions may thus occur at locations where the ablation rate is high. This process may also have important implications on the development of land forms under cold ice sheets.

scholarly journals Interpretation of basal ice conditions from radio-echo soundings in the eastern Heimefrontfjella and the southern Vestfjella mountain ranges, East Antarctica

1993 ◽  
Vol 17 ◽  
pp. 312-316
Author(s):  
Per Holmlund
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Vertical Component ◽  
Ablation Rate ◽  
East Antarctica ◽  
Radio Waves ◽  
Mountain Areas ◽  
Surface Mass ◽  
Ice Conditions ◽  
Basal Melting

Differences in radio-echoes received from the base of the ice sheet covering two different mountain areas in Dronning Maud Land, East Antarctica, are herein interpreted as differences in the physical properties in the ice and differences in basal conditions. An abnormally strong signal can be caused either by unusually little absorption of radio waves within the ice or by water at the base of the glacier.One of the areas studied is totally covered by a 400–1400 m thick ice sheet. The altitude of the surface is about 2800 m a.s.l. The second area is a nunatak area situated relatively closer to the coast. The ice thickness in the valleys is about 500 m and the altitude of the surface is about 400 m.The annual mean surface temperature for the areas is about −30° and −17°C respectively. In both cases ice depths are moderate and flow rates low, and it is thus probable that the ice is frozen to the bed.However, in the colder locality I believe the strong echo is caused by low or negligible rate of mass flux. In the lower area strong bottom echoes are believed to be a cause of negative mass balance at the surface of the blue ice areas. The negative surface mass balance reverses the vertical component of ice flow and it also changes the temperature distribution within the ice. Basal melting conditions may thus occur at locations where the ablation rate is high. This process may also have important implications on the development of land forms under cold ice sheets.

scholarly journals On Mertz and Ninnis Glaciers, East Antarctica

1996 ◽  
Vol 42 (142) ◽  
pp. 447-453 ◽  
Author(s):  
Gerd Wendler ◽  
Kristina Ahlnäs ◽  
Craig S. Lingle
Keyword(s):  
Remote Sensing ◽  
Synthetic Aperture Radar ◽  
Surface Structure ◽  
East Antarctica ◽  
Synthetic Aperture ◽  
Areal Extent ◽  
Glacier Tongue ◽  
Time Period ◽  
Tip Of The Tongue ◽  
Aperture Radar

AbstractTwo large glacier tongues, which extend substantially across the coastline of King George V Land in East Antarctica, have been studied by remote sensing (synthetic aperture radar, JERS-1). The tongue of Mertz Glacier is in a state of advance, while the Ninnis Glacier tongue is retreating. Some more specific points are: The distinctive surface structure and the form of the glacier tongues indicates that they are floating.While the tongue of Ninnis Glacier has lost about two-thirds of its area since 1913, the Mertz Glacier tongue has advanced substantially and has about doubled its areal extent over the same time period.The annual movement of the tongue of Mertz Glacier was determined as about 1.2 km. This is close to the value of the advance of the tip of the tongue since 1963, which was determined as 0.9 km year−1.

scholarly journals On Mertz and Ninnis Glaciers, East Antarctica

1996 ◽  
Vol 42 (142) ◽  
pp. 447-453 ◽  
Author(s):  
Gerd Wendler ◽  
Kristina Ahlnäs ◽  
Craig S. Lingle
Keyword(s):  
Remote Sensing ◽  
Synthetic Aperture Radar ◽  
Surface Structure ◽  
East Antarctica ◽  
Synthetic Aperture ◽  
Areal Extent ◽  
Glacier Tongue ◽  
Time Period ◽  
Tip Of The Tongue ◽  
Aperture Radar

AbstractTwo large glacier tongues, which extend substantially across the coastline of King George V Land in East Antarctica, have been studied by remote sensing (synthetic aperture radar, JERS-1). The tongue of Mertz Glacier is in a state of advance, while the Ninnis Glacier tongue is retreating. Some more specific points are:The distinctive surface structure and the form of the glacier tongues indicates that they are floating.While the tongue of Ninnis Glacier has lost about two-thirds of its area since 1913, the Mertz Glacier tongue has advanced substantially and has about doubled its areal extent over the same time period.The annual movement of the tongue of Mertz Glacier was determined as about 1.2 km. This is close to the value of the advance of the tip of the tongue since 1963, which was determined as 0.9 km year−1.

scholarly journals Spatial and temporal variations in basal melting at Nivlisen ice shelf, East Antarctica, derived from phase-sensitive radars

2019 ◽  
Author(s):  
Katrin Lindbäck ◽  
Geir Moholdt ◽  
Keith W. Nicholls ◽  
Tore Hattermann ◽  
Bhanu Pratap ◽  
...  
Keyword(s):  
Deep Ocean ◽  
Temporal Variations ◽  
East Antarctica ◽  
Spatial And Temporal Variations ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Deep Ocean Water ◽  
Dronning Maud Land ◽  
Phase Sensitive ◽  
Basal Melting

Abstract. Thinning rates of ice shelves vary widely around Antarctica and basal melting is a major component in ice shelf mass loss. In this study, we present records of basal melting, at unique spatial and temporal resolution for East Antarctica, derived from autonomous phase-sensitive radars. These records show spatial and temporal variations of ice shelf basal melting in 2017 and 2018 at Nivlisen, central Dronning Maud Land. The annually averaged melt rates are in general moderate (~ 0.8 m yr-1). Radar profiling of the ice-shelf shows variable ice thickness from smooth beds to basal crevasses and channels. The highest melt rates (3.9 m yr-1) were observed close to a grounded feature near the ice shelf front. Daily time-varying measurements reveal a seasonal melt signal 4 km from the ice shelf front, at an ice draft of 130 m, where the highest daily melt rates occurred in summer (up to 5.6 m yr-1). This seasonality indicates that summer-warmed ocean surface water was pushed by wind beneath the ice shelf front. We observed a different melt regime 35 km into the ice-shelf cavity, at an ice draft of 280 m, with considerably lower melt rates (annual average of 0.4 m yr-1) and no seasonality. We conclude that warm deep ocean water at present has limited effect on the basal melting of Nivlisen. On the other hand, a warming in surface waters, as a result of diminishing sea-ice cover has the potential to increase basal melting near the ice-shelf front. Many ice shelves like Nivlisen are stabilized by pinning points at their ice fronts and these areas may be vulnerable to future change.

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