scholarly journals Geostatistical evaluation of satellite radar altimetry for high-resolution mapping of Lambert Glacier, Antarctica

1993 ◽  
Vol 17 ◽  
pp. 77-85 ◽  
Author(s):  
Ute C. Herzfeld ◽  
Craig S. Lingle ◽  
Li-Her Lee
Keyword(s):  
Noise Levels ◽  
Ice Shelf ◽  
High Resolution Mapping ◽  
Amery Ice Shelf ◽  
Resolution Mapping ◽  
Satellite Radar ◽  
Along Track ◽  
Lambert Glacier ◽  
Inland Ice ◽  
Satellite Radar Altimetry

The potential of satellite radar altimetry for high-resolution mapping of Antarctic ice streams is evaluated, using retracked and slope-corrected data from the Lambert Glacier and Amery Ice Shelf area, East Antarctica, acquired by Geosat during the Exact Repeat Mission (ERM), 1986–89. The map area includes lower Lambert Glacier north of 72.18°S, the southern Amery Ice Shelf, and the grounded inland ice sheet on both sides. The Geosat ERM altimetry is found to provide substantially more complete coverage than the 1978 Seasat altimetry, due to improved tracking. Variogram methods are used to estimate the noise levels in the data as a function of position throughout the map area. The spatial structure in the data is quantified by constructing experimental variograms using altimetry from the area of the grounding zone of Lambert Glacier, which is the area chiefly of interest in this topographically complex region. Kriging is employed to invert the along-track height measurements onto a fine-scale 3 km grid. The unsmoothed along-track Geosat ERM altimetry yields spatially continuous maps showing the main topographic features of lower Lambert Glacier, upper Amery Ice Shelf and the adjacent inland ice sheet. The probable position of the grounding line of Lambert Glacier is identified from a break in slope at the grounded ice/floating ice transition. The approximate standard error of the kriged map is inferred from the data noise levels.

scholarly journals Geostatistical evaluation of satellite radar altimetry for high-resolution mapping of Lambert Glacier, Antarctica

1993 ◽  
Vol 17 ◽  
pp. 77-85 ◽  
Author(s):  
Ute C. Herzfeld ◽  
Craig S. Lingle ◽  
Li-Her Lee
Keyword(s):  
Noise Levels ◽  
Ice Shelf ◽  
High Resolution Mapping ◽  
Amery Ice Shelf ◽  
Resolution Mapping ◽  
Satellite Radar ◽  
Along Track ◽  
Lambert Glacier ◽  
Inland Ice ◽  
Satellite Radar Altimetry

The potential of satellite radar altimetry for high-resolution mapping of Antarctic ice streams is evaluated, using retracked and slope-corrected data from the Lambert Glacier and Amery Ice Shelf area, East Antarctica, acquired by Geosat during the Exact Repeat Mission (ERM), 1986–89. The map area includes lower Lambert Glacier north of 72.18°S, the southern Amery Ice Shelf, and the grounded inland ice sheet on both sides. The Geosat ERM altimetry is found to provide substantially more complete coverage than the 1978 Seasat altimetry, due to improved tracking. Variogram methods are used to estimate the noise levels in the data as a function of position throughout the map area. The spatial structure in the data is quantified by constructing experimental variograms using altimetry from the area of the grounding zone of Lambert Glacier, which is the area chiefly of interest in this topographically complex region. Kriging is employed to invert the along-track height measurements onto a fine-scale 3 km grid. The unsmoothed along-track Geosat ERM altimetry yields spatially continuous maps showing the main topographic features of lower Lambert Glacier, upper Amery Ice Shelf and the adjacent inland ice sheet. The probable position of the grounding line of Lambert Glacier is identified from a break in slope at the grounded ice/floating ice transition. The approximate standard error of the kriged map is inferred from the data noise levels.

scholarly journals Digital elevation models for the Lambert Glacier–Amery Ice Shelf system, East Antarctica, from ERS-1 satellite radar altimetry

2000 ◽  
Vol 46 (155) ◽  
pp. 553-560 ◽  
Author(s):  
Helen A. Fricker ◽  
Glenn Hyland ◽  
Richard Coleman ◽  
Neal W. Young
Keyword(s):  
Digital Elevation Models ◽  
Radar Altimeter ◽  
Ice Shelf ◽  
Waveform Data ◽  
Amery Ice Shelf ◽  
Digital Elevation ◽  
Satellite Radar ◽  
Lambert Glacier ◽  
Satellite Radar Altimetry ◽  
Insight Into

AbstractThe Lambert Glacier–Amery Ice Shelf system is a major component of the East Antarctic ice sheet. This paper presents two digital elevation models (DEMs) that have been generated for the Lambert–Amery system from validated European Remote-sensing Satellite (ERS-1) radar altimeter waveform data. The first DEM covers the Amery Ice Shelf only, and was produced using kriging on a 1 km grid. The second is a coarser (5 km) DEM of the entire Lambert–Amery system, generated via simple averaging procedures. The DEMs provide unprecedented surface elevation information for the Lambert–Amery system and allow new insight into the glaciology of the region.

scholarly journals Recent advance of the grounding line of Lambert Glacier, Antarctica, deduced from satellite-radar altimetry

1994 ◽  
Vol 20 ◽  
pp. 43-47 ◽  
Author(s):  
Ute C. Herzfeld ◽  
Craig S. Lingle ◽  
Li-Her Lee
Keyword(s):  
Ordinary Kriging ◽  
Altimeter Data ◽  
Fine Scale ◽  
Radar Altimeter ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Grounding Line ◽  
Satellite Radar ◽  
Lambert Glacier ◽  
Satellite Radar Altimetry

Satellite radar-altimeter data from Seasat (1978) and the Geosat Exact Repeat Mission (1987–89) are evaluated to investigate the question of advance or retreat of Lambert Glacier, Amery Ice Shelf, East Antarctica. New maps based on a fine-scale 3 km grid arc calculated using ordinary kriging. The break in slope at the 100 m elevation contour, relative to the WGS 1984 ellipsoid, is taken as a proxy for the grounding line. Measurements indicate that the irregular grounding line, which includes shoals, advanced approximately 10km between 1978 and 1987‐89, corresponding to a mean advance rate of about 1000 m year-1.

scholarly journals Recent advance of the grounding line of Lambert Glacier, Antarctica, deduced from satellite-radar altimetry

1994 ◽  
Vol 20 ◽  
pp. 43-47 ◽  
Author(s):  
Ute C. Herzfeld ◽  
Craig S. Lingle ◽  
Li-Her Lee
Keyword(s):  
Ordinary Kriging ◽  
Altimeter Data ◽  
Fine Scale ◽  
Radar Altimeter ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Grounding Line ◽  
Satellite Radar ◽  
Lambert Glacier ◽  
Satellite Radar Altimetry

Satellite radar-altimeter data from Seasat (1978) and the Geosat Exact Repeat Mission (1987–89) are evaluated to investigate the question of advance or retreat of Lambert Glacier, Amery Ice Shelf, East Antarctica. New maps based on a fine-scale 3 km grid arc calculated using ordinary kriging. The break in slope at the 100 m elevation contour, relative to the WGS 1984 ellipsoid, is taken as a proxy for the grounding line. Measurements indicate that the irregular grounding line, which includes shoals, advanced approximately 10km between 1978 and 1987‐89, corresponding to a mean advance rate of about 1000 m year-1.

scholarly journals Antarctic Ice-Shelf Boundaries and Elevations From Satellite Radar Altimetry

1987 ◽  
Vol 9 ◽  
pp. 229-235 ◽  
Author(s):  
H.J. Zwally ◽  
S.N. Stephenson ◽  
R.A. Bindschadler ◽  
R.H. Thomas
Keyword(s):  
Landsat Imagery ◽  
Ice Shelf ◽  
Radar Altimetry ◽  
Systematic Analysis ◽  
Amery Ice Shelf ◽  
Grounding Line ◽  
Fast Ice ◽  
Ice Velocity ◽  
Satellite Radar ◽  
Satellite Radar Altimetry

As part of a systematic analysis of Seasat radar altimetry data to obtain Antarctic ice fronts and ice-shelf elevations north of lat. 72° S., Fimbulisen (between long. 12°W. and 08°E.) and the Amery Ice Shelf (around long. 72°E.) are mapped. Interactive computer analysis is used to examine and correct the altimetry range measurements and derive the ice-front positions. Surface elevations and ice-front positions from radar altimetry are compared with ice fronts, ice rises, crevasse zones, and grounding lines identified in Landsat imagery. By comparison of the visible features in imagery and the computer-contoured elevations from radar altimetry, the radar-elevation mapping on some ice rises is confirmed, but some spurious contours are also identified. During the interval between the 1974 Landsat imagery and the 1978 radar altimetry, the central part of the Amery Ice Shelf front advanced 1.5 ± 0.6 km/a, which is in agreement with the ice-velocity measurements of 1.1 ± 0.1 km/a (Budd and others 1982), suggesting negligible calving in the central part of the ice shelf. The undulating surface and small mean slope from the grounding line to about lat. 70°S. suggest a zone of partial grounding similar to Rutford Ice Stream, On Fimbulisen, some previously unmapped ice rises are identified. The ridge of the Jutul-straumen ice tongue is shown to be about 20 m above the surrounding ice and laterally expanding as it flows northward to the ice front. Icebergs within the sea ice and a zone of shore-fast ice are also identified with the same technique used to map the ice-shelf front.

scholarly journals Antarctic Ice-Shelf Boundaries and Elevations From Satellite Radar Altimetry

1987 ◽  
Vol 9 ◽  
pp. 229-235 ◽  
Author(s):  
H.J. Zwally ◽  
S.N. Stephenson ◽  
R.A. Bindschadler ◽  
R.H. Thomas
Keyword(s):  
Landsat Imagery ◽  
Ice Shelf ◽  
Radar Altimetry ◽  
Systematic Analysis ◽  
Amery Ice Shelf ◽  
Grounding Line ◽  
Fast Ice ◽  
Ice Velocity ◽  
Satellite Radar ◽  
Satellite Radar Altimetry

As part of a systematic analysis of Seasat radar altimetry data to obtain Antarctic ice fronts and ice-shelf elevations north of lat. 72° S., Fimbulisen (between long. 12°W. and 08°E.) and the Amery Ice Shelf (around long. 72°E.) are mapped. Interactive computer analysis is used to examine and correct the altimetry range measurements and derive the ice-front positions. Surface elevations and ice-front positions from radar altimetry are compared with ice fronts, ice rises, crevasse zones, and grounding lines identified in Landsat imagery. By comparison of the visible features in imagery and the computer-contoured elevations from radar altimetry, the radar-elevation mapping on some ice rises is confirmed, but some spurious contours are also identified. During the interval between the 1974 Landsat imagery and the 1978 radar altimetry, the central part of the Amery Ice Shelf front advanced 1.5 ± 0.6 km/a, which is in agreement with the ice-velocity measurements of 1.1 ± 0.1 km/a (Budd and others 1982), suggesting negligible calving in the central part of the ice shelf. The undulating surface and small mean slope from the grounding line to about lat. 70°S. suggest a zone of partial grounding similar to Rutford Ice Stream, On Fimbulisen, some previously unmapped ice rises are identified. The ridge of the Jutul-straumen ice tongue is shown to be about 20 m above the surrounding ice and laterally expanding as it flows northward to the ice front. Icebergs within the sea ice and a zone of shore-fast ice are also identified with the same technique used to map the ice-shelf front.

scholarly journals Evidence for rapid retreat and mass loss of Thwaites Glacier, West Antarctica

2001 ◽  
Vol 47 (157) ◽  
pp. 213-222 ◽  
Author(s):  
Eric Rignot
Keyword(s):  
Ice Thickness ◽  
Interferometric Synthetic Aperture Radar ◽  
West Antarctica ◽  
Ice Shelf ◽  
Amundsen Sea ◽  
Ice Flow ◽  
Grounding Line ◽  
Satellite Radar ◽  
Inland Ice ◽  
Satellite Radar Altimetry

AbstractThwaites Glacier, the second largest ice stream in West Antarctica, drains an area of 166 500 ± 2000 km2 which accumulates 55 ± 5 Gt a−1 (or 60 ± 6 km3 ice a−1) into the Amundsen Sea, unrestrained by an ice shelf. Using interferometric synthetic-aperture radar (InSAR) data collected by the European Remote-sensing Satellites (ERS-1 and -2) in 1996, an output flux of 71 ±7 Gt a−1 (or 77 ± 8 km3 ice a−1) is estimated at the grounding line, where ice thickness is deduced from hydrostatic equilibrium. A similar flux, 70 ± 7 Gt a−1 (or 76 ± 8 km3 ice a−1), is obtained at a gate located 20 km upstream, where ice thickness was measured in 1978 by ice-sounding radar. Total accumulation in between the two gates is 1.6 Gt a−1, or 1.8 km3 ice a−1. Ice discharge therefore exceeds mass accumulation by 30 ± 15%, and Thwaites Glacier must be thinning and retreating at present. The InSAR data show that the glacier floating ice tongue exerts no back pressure on the inland ice, calves into tabular icebergs along a significant fraction of its grounding line, and has a grounding-line thickness which exceeds a prior-calculated limit for stability. Glacier thinning is confirmed at the coast by the detection of a 1.4 ± 0.2 km retreat of its grounding line between 1992 and 1996 with InSAR, which implies 3.2 ± 0.6 m ice a−1 thinning at the glacier center and less near the sides. These results complement the decimeter-scale annual surface lowering observed with satellite radar altimetry several hundred km inland of the grounding line. The magnitude of ice thinning estimated at the coast, however, rules out temporal changes in accumulation as the explanation for surface lowering. Ice thinning must be due to changes in ice flow.

scholarly journals Modelling the response of the Lambert Glacier–Amery Ice Shelf system, East Antarctica, to uncertain climate forcing over the 21st and 22nd centuries

2014 ◽  
Vol 8 (3) ◽  
pp. 1057-1068 ◽  
Author(s):  
Y. Gong ◽  
S. L. Cornford ◽  
A. J. Payne
Keyword(s):  
Climate Model ◽  
Global Environmental Change ◽  
Ice Sheet ◽  
Adaptive Mesh ◽  
Ocean Model ◽  
East Antarctica ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Grounding Line ◽  
Lambert Glacier

Abstract. The interaction between the climate system and the large polar ice sheet regions is a key process in global environmental change. We carried out dynamic ice simulations of one of the largest drainage systems in East Antarctica: the Lambert Glacier–Amery Ice Shelf system, with an adaptive mesh ice sheet model. The ice sheet model is driven by surface accumulation and basal melt rates computed by the FESOM (Finite-Element Sea-Ice Ocean Model) ocean model and the RACMO2 (Regional Atmospheric Climate Model) and LMDZ4 (Laboratoire de Météorologie Dynamique Zoom) atmosphere models. The change of ice thickness and velocity in the ice shelf is mainly influenced by the basal melt distribution, but, although the ice shelf thins in most of the simulations, there is little grounding line retreat. We find that the Lambert Glacier grounding line can retreat as much as 40 km if there is sufficient thinning of the ice shelf south of Clemence Massif, but the ocean model does not provide sufficiently high melt rates in that region. Overall, the increased accumulation computed by the atmosphere models outweighs ice stream acceleration so that the net contribution to sea level rise is negative.

scholarly journals Radio-echo sounding of the lambert glacier basin

1975 ◽  
Vol 15 (73) ◽  
pp. 103-111 ◽  
Author(s):  
V. I. Morgan ◽  
W. F. Budd
Keyword(s):  
Surface Topography ◽  
Sea Level ◽  
Drainage Basin ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Deep Trench ◽  
Glacier System ◽  
Amery Ice Shelf ◽  
Lambert Glacier ◽  
Echo Sounding

AbstractSeveral seasons of aerial ice-thickness soundings over the region of the Prince Charles Mountains, the Lambert Glacier system, the Amery Ice Shelf, and their drainage basin in east Antarctica have now been completed. The measurements provide detailed maps of surface topography and ice thickness over an area of about 2 X 105 km2. The equipment used consisted of a 100 MHz echo sounder designed and constructed by Antarctic Division and carried in a Pilatus Porter aircraft. ERTS imagery provides a valuable background for portraying the echo-sounding results. These results show that an extensive, deep subglacial valley system forms the basis of the large drainage basin with concave ice surface topography which channels the ice flow into the Amery Ice Shelf. Deep glacial streams penetrate a long way into the ice-sheet basin. The rock relief is considerable, varying from 3 000 m above (present) sea-level to 2 000 m below sea-level. A very deep subglacial trench exists in the region of the confluence of the Fisher, Mellor, and Lambert Glaciers where the ice thickness reaches 2 500 m. The low surface slope and high ice velocity are suggestive of high melt production in this region. The strong echo, together with the high bedrock back-slope, suggests that the deep trench may contain a basal melt lake.

scholarly journals Surging of Fisher Glacier, Eastern Antarctica: Evidence From Geomorphology

1982 ◽  
Vol 28 (98) ◽  
pp. 23-28 ◽  
Author(s):  
Peter Wellman
Keyword(s):  
Climatic Change ◽  
The Other ◽  
Present Level ◽  
Altitude Range ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Lambert Glacier

AbstractA study of the geomorphology of the Prince Charles Mountains using colour vertical air photographs shows well–preserved old moraines throughout much of the outcrop area. Along Fisher Glacier, lower Lambert Glacier and the Amery Ice Shelf, within the altitude range 50–2 000 m, the old moraines show that the ice level had risen 150–200 m above the present level at least three times. Old moraines elsewhere show that none of the other glaciers had risen significantly in their upper parts; the rise of their lower parts was caused by the rise of lower Lambert Glacier and the Amery Ice Shelf. The changes in ice level are unlikely to be due to climatic change because this would not repeatedly affect only one glacier draining central Antarctica. It is thought that the changes in ice level are caused by repeated surges of Fisher Glacier.

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