Ice Surface Elevation of Central Marie Byrd Land

1962 ◽  
Vol 4 (31) ◽  
pp. 121-123 ◽  
Author(s):  
J. C. Behrendt ◽  
R. J. Wold ◽  
F. L. Dowling
Keyword(s):  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Surface ◽  
Altimetric Data ◽  
The Antarctic

An ice surface map of central Marie Byrd Land has been compiled from aero-altimetric data taken on 14,000 km. of flight lines during the Antarctic summer of 1960–61 using standard aircraft equipment. A large depression sloping down towards the Filchner Ice Shelf was determined and earlier known features in the area are shown in greater detail.

scholarly journals Ice Surface Elevation of Central Marie Byrd Land

1962 ◽  
Vol 4 (31) ◽  
pp. 121-123
Author(s):  
J. C. Behrendt ◽  
R. J. Wold ◽  
F. L. Dowling
Keyword(s):  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Surface ◽  
Altimetric Data ◽  
The Antarctic

AbstractAn ice surface map of central Marie Byrd Land has been compiled from aero-altimetric data taken on 14,000 km. of flight lines during the Antarctic summer of 1960–61 using standard aircraft equipment. A large depression sloping down towards the Filchner Ice Shelf was determined and earlier known features in the area are shown in greater detail.

scholarly journals Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

2013 ◽  
Vol 7 (3) ◽  
pp. 797-816 ◽  
Author(s):  
T. O. Holt ◽  
N. F. Glasser ◽  
D. J. Quincey ◽  
M. R. Siegfried
Keyword(s):  
Antarctic Peninsula ◽  
Structural Changes ◽  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Shelves ◽  
The North ◽  
Surface Elevation Change ◽  
Elevation Changes ◽  
Negative Surface ◽  
The Antarctic

Abstract. George VI Ice Shelf (GVIIS) is located on the Antarctic Peninsula, a region where several ice shelves have undergone rapid breakup in response to atmospheric and oceanic warming. We use a combination of optical (Landsat), radar (ERS 1/2 SAR) and laser altimetry (GLAS) datasets to examine the response of GVIIS to environmental change and to offer an assessment on its future stability. The spatial and structural changes of GVIIS (ca. 1973 to ca. 2010) are mapped and surface velocities are calculated at different time periods (InSAR and optical feature tracking from 1989 to 2009) to document changes in the ice shelf's flow regime. Surface elevation changes are recorded between 2003 and 2008 using repeat track ICESat acquisitions. We note an increase in fracture extent and distribution at the south ice front, ice-shelf acceleration towards both the north and south ice fronts and spatially varied negative surface elevation change throughout, with greater variations observed towards the central and southern regions of the ice shelf. We propose that whilst GVIIS is in no imminent danger of collapse, it is vulnerable to ongoing atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

scholarly journals Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

2013 ◽  
Vol 7 (1) ◽  
pp. 373-417 ◽  
Author(s):  
T. O. Holt ◽  
N. F. Glasser ◽  
D. J. Quincey ◽  
M. R. Siegfried
Keyword(s):  
Antarctic Peninsula ◽  
Structural Changes ◽  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Shelves ◽  
The North ◽  
Surface Elevation Change ◽  
Elevation Changes ◽  
Negative Surface ◽  
The Antarctic

Abstract. George VI Ice Shelf (GVIIS) is located on the Antarctic Peninsula, a region where several ice shelves have undergone rapid breakup in response to atmospheric and oceanic warming. We use a combination of optical (Landsat), radar (ERS 1/2 SAR) and laser altimetry (GLAS) datasets to examine the response of GVIIS to environmental change and to offer an assessment on its future stability. The spatial and structural changes of GVIIS (ca. 1973 to ca. 2010) are mapped and surface velocities are calculated at different time periods (InSAR and optical feature tracking from 1989 to 2009) to document changes in the ice shelf's flow regime. Surface elevation changes are recorded between 2003 and 2008 using repeat track ICESat acquisitions. We note an increase in fracture extent and distribution at the south ice front, ice-shelf acceleration towards both the north and south ice fronts and spatially varied negative surface elevation change throughout, with greater variations observed towards the central and southern regions of the ice shelf. We propose that whilst GVIIS is in no imminent danger of collapse, it is vulnerable to on-going atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

scholarly journals Changes of Wilkins Ice Shelf over the past 15 years and inferences on its stability

2009 ◽  
Vol 3 (1) ◽  
pp. 41-56 ◽  
Author(s):  
M. Braun ◽  
A. Humbert ◽  
A. Moll
Keyword(s):  
Sar Interferometry ◽  
Tidal Effects ◽  
Ice Shelf ◽  
Structural Mapping ◽  
Ice Shelves ◽  
Ice Surface ◽  
Melt Ponds ◽  
Elevation Data ◽  
Break Up ◽  
The Antarctic

Abstract. The Wilkins Ice Shelf is situated on the Antarctic Peninsula, a region where seven ice shelves disintegrated or retreated between 1995 and 2002. This study combines various remote sensing datasets from Wilkins Ice Shelf, with the aim of detecting its present and recent dynamics as well as recent changes. The survey includes structural mapping, ERS-1/2 SAR interferometry and analysis of ICESat GLAS ice surface elevation data. Ice front retreat rates from 1986 to 2008 showed several distinct break-up events, including one in February 2008, when 40% of a part of the ice shelf that connected two islands broke off. Surface elevations have been used to study tidal effects, crack formation and to estimate the ice thickness over the floating area. The derived interferometric velocities cover the south-eastern part of the ice shelf as well as major tributaries and reveal maximum inflow speeds of up to 330 m a−1. We show that drainage of melt ponds into crevasses were of no relevance for the break-up at Wilkins Ice Shelf. Buoyancy forces caused rift formation before the break-up in February 2008. Additionally, the evolution of failure zones of the order of tenths of kilometres in length in pre-conditioned locations at ice rises is shown. Investigation of the current (February 2009) situation shows that about 3100 km2 at the Northern Wilkins Ice Shelf are endangered, however, there is no visible signature that the remaining 8000 km2 are at risk.

scholarly journals Geostatistical methods for mapping Antarctic ice surfaces at continental and regional scales

2000 ◽  
Vol 30 ◽  
pp. 76-82 ◽  
Author(s):  
Ute Christina Herzfeld ◽  
Ralf Stosius ◽  
Marcus Schneider
Keyword(s):  
Surface Elevation ◽  
Altimeter Data ◽  
Radar Altimeter ◽  
Sea Level Changes ◽  
Ice Streams ◽  
Geostatistical Methods ◽  
Ice Surface ◽  
Geophysical Study ◽  
Satellite Radar ◽  
The Antarctic

AbstractThe Antarctic ice sheet plays a major role in the global system and the large ice streams discharging into the circumpolar sea represent its gateways to the world’s oceans. Satellite radar-altimeter data provide an opportunity for mapping surface elevation at kilometer resolution with meter accuracy. Geostatistical methods have been developed to accomplish this. We distinguish two goals in mapping the Antarctic ice surface: (a) construction of a continent-wide atlas of maps and digital terrain models, and (b) calculation of maps and models suitable for the study of individual glaciers, ice streams and ice shelves. The atlases consist of accurate maps of ice-surface elevation compiled from Seasat, Geosat and ERS-1 altimeter data, covering all of Antarctica surveyed by Geosat (to 72.1° S) and by ERS-1 (to 81.5° S). With a 3 km grid they are the highest-resolution maps available today with continent-wide coverage. The resolution permits geophysical study and facilitates monitoring of changes in ice-surface elevation and changes in flux across the ice-ocean boundary, which is essential for monitoring sea-level changes.

New ice thickness maps of Filchner–Ronne Ice Shelf, Antarctica, with specific focus on grounding lines and marine ice

2007 ◽  
Vol 19 (4) ◽  
pp. 521-532 ◽  
Author(s):  
A. Lambrecht ◽  
H. Sandhäger ◽  
D.G. Vaughan ◽  
C. Mayer
Keyword(s):  
Surface Elevation ◽  
Small Scale ◽  
Ice Thickness ◽  
Line Position ◽  
Ice Shelf ◽  
Ice Surface ◽  
Seismic Sounding ◽  
Grounding Line ◽  
Data Coverage

AbstractFor the Filchner–Ronne Ice Shelf we have compiled measurements of meteoric ice thickness from many institutions, and several different techniques (e.g. radar and seismic sounding) to produce an improved digital map of meteoric ice thickness. This map has high-resolution compared to previous compilations and serves to highlight small-scale geographic features (e.g. ice plains, grounding-line regions). We have also produced a map of the thickness of marine ice bodies beneath the ice shelf by using borehole density data to calibrate an ice thickness to surface-elevation relation, and then comparing maps of ice surface elevation and meteoric ice thickness to infer marine ice thickness. Due to denser data coverage and the improved density-depth relation, the resulting map is a significant improvement on its predecessors and allows insight into the glaciological context of the ice shelf, in particular, into the location of the grounding lines on the southern Ronne Ice Shelf. Here the data were supplemented with barometric determination of surface elevation, which were used to locate the grounding line position. The final delineation of the grounding line position was confirmed by reference to satellite imagery, and revealed that earlier estimates were substantially in error, especially in the area of Foundation Ice Stream and Möllereisstrom.

scholarly journals Modeling the dynamic response of outlet glaciers to observed ice-shelf thinning in the Bellingshausen Sea Sector, West Antarctica

2018 ◽  
Vol 64 (244) ◽  
pp. 333-342 ◽  
Author(s):  
BRENT M. MINCHEW ◽  
G. HILMAR GUDMUNDSSON ◽  
ALEX S. GARDNER ◽  
FERNANDO S. PAOLO ◽  
HELEN A. FRICKER
Keyword(s):  
Dynamic Response ◽  
Mass Loss ◽  
Gravity Anomalies ◽  
Surface Elevation ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Ice Surface ◽  
Mass Losses ◽  
Bellingshausen Sea

ABSTRACTSatellite observations of gravity anomalies, ice-surface elevation and glacier velocity show significant increases in net grounded-ice-mass loss over the past decade along the Bellingshausen Sea sector (BSS), West Antarctica, in areas where warm (>1°C) sea water floods the continental shelf. These observations provide compelling but indirect evidence that mass losses are driven primarily by reduced buttressing from the floating ice shelves caused by ocean-driven ice-shelf thinning. Here, we combine recent observations of ice velocity, thickness and thickness changes with an ice flow model to study the instantaneous dynamic response of BSS outlet glaciers to observed ice-shelf thinning, alone. Our model results show that multiple BSS outlet glaciers respond instantaneously to observed ice-shelf thinning, particularly in areas where ice shelves ground at discrete points. Increases in modeled and observed dynamic mass losses, however, account for ~5% of the mass loss rates estimated from gravity anomalies and changes in ice-surface elevation, suggesting that variations in surface mass balance may be key to understanding recent BSS mass loss. Our approach isolates the impact of ice-shelf thinning on glacier flow and shows that if ice-shelf thinning continues at or above current rates, total BSS mass loss will increase in the next decade.

scholarly journals Boundary conditions of an active West Antarctic subglacial lake: implications for storage of water beneath the ice sheet

2013 ◽  
Vol 7 (3) ◽  
pp. 2979-2999 ◽  
Author(s):  
M. J. Siegert ◽  
N. Ross ◽  
H. Corr ◽  
B. Smith ◽  
T. Jordan ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Surface Elevation ◽  
Altimeter Data ◽  
Radar Altimeter ◽  
Local Flow ◽  
Antarctic Ice Sheet ◽  
Subglacial Lake ◽  
West Antarctic ◽  
Ice Surface ◽  
The Antarctic

Abstract. Repeat-pass IceSat altimetry has revealed 124 discrete surface height changes across the Antarctic Ice Sheet, interpreted to be caused by subglacial lake discharges (surface lowering) and inputs (surface uplift). Few of these active lakes have been confirmed by radio-echo sounding (RES) despite several attempts (notable exceptions are Lake Whillans and three in the Adventure Subglacial Trench). Here we present targeted RES and radar altimeter data from an "active lake" location within the upstream Institute Ice Stream, into which 0.12 km3 of water is calculated to have flowed between October 2003 and February 2008. We use a series of transects to establish an accurate appreciation of the influences of bed topography and ice-surface elevation on water storage potential. The location of surface height change is over the downslope flank of a distinct topographic hollow, where RES reveals no obvious evidence for deep (> 10 m) water. The regional hydropotential reveals a sink coincident with the surface change, however. Governed by the location of the hydrological sink, basal water will likely "drape" over existing topography in a manner dissimilar to subglacial lakes where flat strong specular RES reflections are measured. The inability of RES to detect the active lake means that more of the Antarctic ice sheet bed may contain stored water than is currently appreciated. Variation in ice surface elevation datasets leads to significant alteration in calculations of the local flow of basal water indicating the value of, and need for, high resolution RES datasets in both space and time to establish and characterise subglacial hydrological processes.

scholarly journals Surface lowering of the ice ramp at Rother a Point, Antarctic Peninsula, in response to regional climate change

1998 ◽  
Vol 27 ◽  
pp. 113-118 ◽  
Author(s):  
A. M. Smith ◽  
D. G. Vaughan ◽  
C. S. M. Doake ◽  
A. C. Johnson
Keyword(s):  
Antarctic Peninsula ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Level Line ◽  
Surface Elevation ◽  
Clear Trend ◽  
Surface Mass ◽  
Ice Surface ◽  
Air Temperatures ◽  
The Antarctic

Level-line surveys at a number of sites on the Antarctic Peninsula since the early 1970s have shown a lowering of the ice surface elevation in areas where the climate is warm enough for melting to occur during summer. Results are presented here from annual surveys on the ice ramp at Rothcra Point. Over an 8 year period, a large proportion of the ramp shows a generally steady reduction in surface elevation. The uppermost part of the ramp shows no clear trend. The ice ramp has suffered a mean rate ofsurfaee lowering of 0.32 ma−1 w.e. over the period of the surveys, which is similar to that seen at other sites on the Antarctic Peninsula. Measured ice velocities on the ramp are low, so the surface lowering can be attributed directly to changes in surface mass balance. The Surveys coincide with a period of long-term increase in temperature and ablation seen in meteorological records. Comparison of the observed surface lowering with temperature data shows a good agreement, and we conclude that increasing air temperatures in the region will raise ablation and increase the recession rate of the ice ramp.

scholarly journals Boundary conditions of an active West Antarctic subglacial lake: implications for storage of water beneath the ice sheet

2014 ◽  
Vol 8 (1) ◽  
pp. 15-24 ◽  
Author(s):  
M. J. Siegert ◽  
N. Ross ◽  
H. Corr ◽  
B. Smith ◽  
T. Jordan ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Surface Elevation ◽  
Altimeter Data ◽  
Radar Altimeter ◽  
Local Flow ◽  
Antarctic Ice Sheet ◽  
Subglacial Lake ◽  
West Antarctic ◽  
Ice Surface ◽  
The Antarctic

Abstract. Repeat-pass ICESat altimetry has revealed 124 discrete surface height changes across the Antarctic Ice Sheet, interpreted to be caused by subglacial lake discharges (surface lowering) and inputs (surface uplift). Few of these active lakes have been confirmed by radio-echo sounding (RES) despite several attempts (notable exceptions are Lake Whillans and three in the Adventure Subglacial Trench). Here we present targeted RES and radar altimeter data from an "active lake" location within the upstream Institute Ice Stream, into which at least 0.12 km3 of water was previously calculated to have flowed between October 2003 and February 2008. We use a series of transects to establish an accurate depiction of the influences of bed topography and ice surface elevation on water storage potential. The location of surface height change is downstream of a subglacial hill on the flank of a distinct topographic hollow, where RES reveals no obvious evidence for deep (> 10 m) water. The regional hydropotential reveals a sink coincident with the surface change, however. Governed by the location of the hydrological sink, basal water will likely "drape" over topography in a manner dissimilar to subglacial lakes where flat strong specular RES reflections are measured. The inability of RES to detect the active lake means that more of the Antarctic ice sheet bed may contain stored water than is currently appreciated. Variation in ice surface elevation data sets leads to significant alteration in calculations of the local flow of basal water indicating the value of, and need for, high-resolution altimetry data in both space and time to establish and characterise subglacial hydrological processes.

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