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 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 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 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 Geostatistical estimation from radar altimeter data with respect to morphological units outlined by SAR data: application to Lambert Glacier/Amery Ice Shelf, East Antarctica

2004 ◽  
Vol 39 ◽  
pp. 251-255 ◽  
Author(s):  
Ralf Stosius ◽  
Ute C. Herzfeld
Keyword(s):  
Surface Characteristics ◽  
East Antarctica ◽  
Morphological Properties ◽  
Altimeter Data ◽  
Shelf Area ◽  
Radar Altimeter ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Sar Data ◽  
Lambert Glacier

AbstractThe objective of this paper is the comparison of two kriging methods, ordinary kriging and kriging within strata, for calculation of digital elevation models (DEMs) from radar altimeter data, and application to the Lambert Glacier/Amery Ice Shelf system, East Antarctica. Two new DEMs are presented. First, a DEM of the Lambert Glacier/Amery Ice Shelf system is calculated from 1997 European Remote-sensing Satellite-2 (ERS-2) radar altimeter (RA) data using geostatistical interpolation. RA data have high along-track density, but gaps between tracks are several kilometers, depending on the observation mode; this requires interpolation. Because the ice-stream/ice-shelf system is of primary interest in glaciological investigations, in the first approach a variogram characteristic of the Lambert Glacier ice surface is used. The resultant map has low errors for the glacier and the ice shelf. To match the surface characteristics of different morphological units that constitute the Lambert Glacier/Amery Ice Shelf region, a second DEM is constructed as follows: We utilize RADARSAT synthetic aperture radar (SAR) data that were collected in 1997 during the first Antarctic Imaging Campaign and composed into a 125m backscatter-data mosaic by Jezek (1999) and we co-reference the 125m mosaic with the altimetry-derived DEM. The Lambert Glacier/Amery Ice Shelf area is then subdivided into several regions which are homogeneous with respect to characteristic surface-morphological properties identified in the SAR mosaic. For those regions, a problem-oriented complex kriging method known as kriging within strata is performed, and the resulting DEM is compared to the DEM that was derived from kriging without regional subdivision.

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 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 Mass balance of the Lambert Glacier–Amery Ice Shelf system, East Antarctica: a comparison of computed balance fluxes and measured fluxes

2000 ◽  
Vol 46 (155) ◽  
pp. 561-570 ◽  
Author(s):  
Helen A. Fricker ◽  
Roland C. Warner ◽  
Ian Allison
Keyword(s):  
Mass Balance ◽  
Drainage System ◽  
Radar Altimeter ◽  
Drainage Basins ◽  
Ice Shelf ◽  
Amery Ice Shelf ◽  
Ice Sheet Mass Balance ◽  
Lambert Glacier ◽  
Lambert Glacier Basin

AbstractWe combine European Remote-sensing Satellite (ERS-1) radar altimeter surface elevations (Fricker and others, 2000) with six different accumulation distributions to compute balance fluxes for the Lambert Glacier–Amery Ice Shelf drainage system. These interpolated balance fluxes are compared with fluxes derived from in situ measurements of ice thickness and velocity at 73 stations of the Lambert Glacier basin traverse and at 11 stations further downstream, to assess the system’s state of balance. For the upstream line we obtain a range of imbalance estimates, from −23.8% to +19.9% of the observed flux, reflecting the sensitivity to the accumulation distributions. For some of the accumulation distributions the imbalance estimates vary significantly between different parts of the line. Imbalance estimates for the downstream line range from −17.7% to +70.2%, with four of the estimates exceeding +30%, again reflecting the sensitivity of the result to input accumulation, and strongly suggesting that the mass balance of the region between the two lines is positive. Our results confirm the importance of accurate estimates of accumulation in ice-sheet mass-balance studies. Furthermore, they suggest that it is not possible to accurately determine the state of balance of large Antarctic drainage basins on the basis of currently available accumulation distributions.

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