scholarly journals Subglacial Morphology in Northern Palmer Land, Antarctic Peninsula

1981 ◽  
Vol 2 ◽  
pp. 17-22 ◽  
Author(s):  
R.D. Crabtree
Keyword(s):  
Antarctic Peninsula ◽  
Important Influence ◽  
Surface Elevation ◽  
Ice Thickness ◽  
Geological Evidence ◽  
Contour Maps ◽  
Divergent Flow ◽  
Elevation Data ◽  
Subglacial Topography ◽  
The Antarctic

Ice-thickness and surface-elevation data gathered from radio echo flights over the Antarctic Peninsula are presented as profiles for five major outlet glaciers in northern Palmer Land and as contour maps for an area of 8 000 km2 to the east of George VI Sound. Glacier profiles appear to be closely related to ice discharge especially to convergent and divergent flow. Comparison of subglacial topography with geological evidence of faulting suggests that the area around George VI Sound is a region where structure is an important influence on the pattern of glacial erosion.

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 Ice-Flow and Thickness Measurements in the Sør-Rondane, Dronning Maud Land, Antarctica

1966 ◽  
Vol 6 (43) ◽  
pp. 69-81
Author(s):  
T. Van Autenboer ◽  
K. V. Blaiklock
Keyword(s):  
Aerial Photographs ◽  
Surface Velocity ◽  
Ice Thickness ◽  
Gravity Station ◽  
Close Relationship ◽  
Dronning Maud Land ◽  
Subglacial Topography ◽  
Glacier Flow ◽  
The Antarctic ◽  
Thickness Measurements

AbstractVelocity and ice-thickness profiles were measured un the western glaciers of the Sør-Rondane during the Expéditions Antarctiques Belges of 1959 and 1960 Some of the stations were re-occupied for velocity measurements during the Expédition Antarctique Belgo-Néerlandaise, Campagne d’Été 1964–65.The profiles, with stations at 1 mile. (1.6 km.) intervals, were generally east-west and at right-angles to the direction of flow of the plateau outlet glaciers. The movement was measured by resection of each station from the main triangulation points over periods ranging from 256 to 1,501 days. Double ties with a Worden geodetic-type gravity meter were measured between the stations. An additional gravity station was occupied on rock at each end of the profile. The ice thickness and the subglacial topography are calculated from the gravity profiles. Combined with the surface velocity, they allow an estimate of the discharge of the glacier. The results indicate a close relationship between the glacier flow and the supply from the Antarctic Ice Sheet, as demonstrated by a study of the aerial photographs.

scholarly journals Geometric boundary conditions for modelling the velocity field of the Antarctic ice sheet

1996 ◽  
Vol 23 ◽  
pp. 364-373 ◽  
Author(s):  
Jonathan L. Bamber ◽  
Philippe Huybrechts
Keyword(s):  
Velocity Field ◽  
Boundary Conditions ◽  
Ice Sheet ◽  
Surface Elevation ◽  
Surface Velocity ◽  
Ice Thickness ◽  
Antarctic Ice Sheet ◽  
Surface Slopes ◽  
Geometric Boundary ◽  
The Antarctic

This paper presents improved geometric boundary conditions (surface elevation and ice thickness) required as inputs to calculations of the surface-velocity field for the Antarctic ice sheet. A comparison of the two-dimensional horizontal velocity field obtained on the basis of conservation of mass (balance velocity) with the diagnostic velocity field calculated with an ice-sheet model (dynamic velocity) may yield information on shortcomings in the way the ice-sheet model describes the ice flow. Here, the surface-elevation grid is described in detail, as it has been generated specifically for such a study and represents a new standard in accuracy and resolution for calculating surface slopes. The digital-elevation model was generated on a 10 km grid size from over 20 000 000 height estimates obtained from eight 35 d repeat cycles of ERS-1 radar-altimeter data. For surface slopes less than 0.4°, the accuracy is better than 1.5 m. In areas of high surface slope (coastal and mountainous regions), the altimeter measurements have been supplemented with data taken from the Antarctic Digital Database. South of 81.5°, data from the SPRI folio map have been used. The ice-thickness grid was produced from a combination of a redigitization of the SPRI folio and the original radio-echo-sounding flight lines. For areas of grounded ice, the elevation of the bed was estimated from surface elevation and ice thickness. Significant differences (in excess of 25% of ice thickness) were obtained between an earlier digitization of the folio bed-elevation map and the data set derived here. Furthermore, a new value of 25.6 × 106 km3 was obtained for the total volume of the ice sheet and ice shelves, which is a reduction of 12% compared with the original estimate derived during the compilation of the SPRI folio. These differences will have an important influence on the results obtained by numerical ice-sheet models.

scholarly journals A high-resolution bedrock map for the Antarctic Peninsula

2014 ◽  
Vol 8 (4) ◽  
pp. 1261-1273 ◽  
Author(s):  
M. Huss ◽  
D. Farinotti
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Antarctic Peninsula ◽  
Dynamic Modelling ◽  
Ice Thickness ◽  
Data Set ◽  
Ice Flow ◽  
Study Region ◽  
Entire Study ◽  
The Antarctic

Abstract. Assessing and projecting the dynamic response of glaciers on the Antarctic Peninsula to changed atmospheric and oceanic forcing requires high-resolution ice thickness data as an essential geometric constraint for ice flow models. Here, we derive a complete bedrock data set for the Antarctic Peninsula north of 70° S on a 100 m grid. We calculate distributed ice thickness based on surface topography and simple ice dynamic modelling. Our approach is constrained with all available thickness measurements from Operation IceBridge and gridded ice flow speeds for the entire study region. The new data set resolves the rugged subglacial topography in great detail, indicates deeply incised troughs, and shows that 34% of the ice volume is grounded below sea level. The Antarctic Peninsula has the potential to raise global sea level by 69 ± 5 mm. In comparison to Bedmap2, covering all Antarctica on a 1 km grid, a significantly higher mean ice thickness (+48%) is found.

Nature of the Antarctic Peninsula Ice Sheet during the Pliocene: Geological evidence and modelling results compared

2009 ◽  
Vol 94 (1-4) ◽  
pp. 79-94 ◽  
Author(s):  
John L. Smellie ◽  
Alan M. Haywood ◽  
Claus-Dieter Hillenbrand ◽  
Daniel J. Lunt ◽  
Paul J. Valdes
Keyword(s):  
Antarctic Peninsula ◽  
Ice Sheet ◽  
Geological Evidence ◽  
The Antarctic

scholarly journals A high-resolution bedrock map for the Antarctic Peninsula

2014 ◽  
Vol 8 (1) ◽  
pp. 1191-1225
Author(s):  
M. Huss ◽  
D. Farinotti
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Antarctic Peninsula ◽  
Dynamic Modelling ◽  
Ice Thickness ◽  
Data Set ◽  
Ice Flow ◽  
Study Region ◽  
Entire Study ◽  
The Antarctic

Abstract. Assessing and projecting the dynamic response of glaciers on the Antarctic Peninsula to changed atmospheric and oceanic forcing requires high-resolution ice thickness data as an essential geometric constraint for ice flow models. Here, we derive a complete bedrock data set for the Antarctic Peninsula north of 70° S on a 100 m grid. We calculate distributed ice thickness based on surface topography and simple ice dynamic modelling. Our approach is constrained with all available thickness measurements from Operation IceBridge and gridded ice flow speeds for the entire study region. The new data set resolves the rugged subglacial topography in great detail, indicates deeply incised troughs, and shows that 34% of the ice volume is grounded below sea level. The Antarctic Peninsula has the potential to raise global sea level by 71 ± 5 mm. In comparison to Bedmap2, covering all Antarctica on a 1 km grid, a significantly higher mean ice thickness (+48%) is found.

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 Ice-Flow and Thickness Measurements in the Sør-Rondane, Dronning Maud Land, Antarctica

1966 ◽  
Vol 6 (43) ◽  
pp. 69-81 ◽  
Author(s):  
T. Van Autenboer ◽  
K. V. Blaiklock
Keyword(s):  
Aerial Photographs ◽  
Surface Velocity ◽  
Ice Thickness ◽  
Gravity Station ◽  
Close Relationship ◽  
Dronning Maud Land ◽  
Subglacial Topography ◽  
Glacier Flow ◽  
The Antarctic ◽  
Thickness Measurements

AbstractVelocity and ice-thickness profiles were measured un the western glaciers of the Sør-Rondane during the Expéditions Antarctiques Belges of 1959 and 1960 Some of the stations were re-occupied for velocity measurements during the Expédition Antarctique Belgo-Néerlandaise, Campagne d’Été 1964–65.The profiles, with stations at 1 mile. (1.6 km.) intervals, were generally east-west and at right-angles to the direction of flow of the plateau outlet glaciers. The movement was measured by resection of each station from the main triangulation points over periods ranging from 256 to 1,501 days. Double ties with a Worden geodetic-type gravity meter were measured between the stations. An additional gravity station was occupied on rock at each end of the profile. The ice thickness and the subglacial topography are calculated from the gravity profiles. Combined with the surface velocity, they allow an estimate of the discharge of the glacier. The results indicate a close relationship between the glacier flow and the supply from the Antarctic Ice Sheet, as demonstrated by a study of the aerial photographs.

scholarly journals Surface elevation changes on Lachman Crags ice caps (north-eastern Antarctic Peninsula) since 1979 indicated by DEMs and ICESat data

2019 ◽  
Vol 65 (251) ◽  
pp. 410-421 ◽  
Author(s):  
ZBYNĚK ENGEL ◽  
JAN KROPÁČEK ◽  
JANA SMOLÍKOVÁ
Keyword(s):  
20Th Century ◽  
Antarctic Peninsula ◽  
Surface Elevation ◽  
Aerial Photographs ◽  
Altimeter Data ◽  
Glacier Surface ◽  
Ice Caps ◽  
North Eastern ◽  
Elevation Changes ◽  
The Antarctic

ABSTRACTThe long-term warming on the Antarctic Peninsula in the second half of the 20th century prompted rapid retreat of glaciers on the peninsula and surrounding islands. Retreat accelerated until the beginning of the new millennium when the regional warming trend significantly decreased. The response of glaciers to the change in temperature trend has been observed around the northern part of the Antarctic Peninsula but the timing of the shift from the surface lowering to mass gain remains unclear. Using historical aerial photographs, DEMs and satellite altimeter data from ICESat, we estimate areal and surface elevation changes of two small ice caps in the northern part of James Ross Island over the last 39 years. The glacierized area on Lachman Crags decreased from 4.337 ± 0.037 to 3.581 ± 0.014 km2 (−17.4%) between 1979 and 2006 and then increased to 3.597 ± 0.047 km2 (0.4%) until 2016. Surface lowering observed on ice caps after 1979 continued at least until 2008 as indicated by the ICESat data. The change from the lowering trend to increase in glacier surface elevation probably occurred after the ablation season 2008/09, which ranks among the warmest summers in the north-eastern Antarctic Peninsula since the mid-20th century.

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