scholarly journals The Dynamics of the Ross Ice Shelf Revealed by Radio Echo-Sounding

1979 ◽  
Vol 24 (90) ◽  
pp. 295-307 ◽  
Author(s):  
C. S. Neal
Keyword(s):  
Dielectric Loss ◽  
Water Interface ◽  
Ice Shelf ◽  
Flow Lines ◽  
Regional Variations ◽  
Distinctive Features ◽  
Ross Ice Shelf ◽  
Radio Echo Sounding ◽  
Ice Water ◽  
Echo Sounding

AbstractRadio-echo data have yielded information on the dynamics of the Ross Ice Shelf. Distinctive features present on the radio-echo records have been used to delineate several flow lines on the ice shelf. Measurement of the power returned from the ice-water interface has revealed regional variations in the r.f. dielectric loss of Ross Ice Shelf ice. These variations are used to indicate zones of bottom melting and freezing.

scholarly journals The Dynamics of the Ross Ice Shelf Revealed by Radio Echo-Sounding

1979 ◽  
Vol 24 (90) ◽  
pp. 295-307 ◽  
Author(s):  
C. S. Neal
Keyword(s):  
Dielectric Loss ◽  
Water Interface ◽  
Ice Shelf ◽  
Flow Lines ◽  
Regional Variations ◽  
Distinctive Features ◽  
Ross Ice Shelf ◽  
Radio Echo Sounding ◽  
Ice Water ◽  
Echo Sounding

AbstractRadio-echo data have yielded information on the dynamics of the Ross Ice Shelf. Distinctive features present on the radio-echo records have been used to delineate several flow lines on the ice shelf. Measurement of the power returned from the ice-water interface has revealed regional variations in the r.f. dielectric loss of Ross Ice Shelf ice. These variations are used to indicate zones of bottom melting and freezing.

scholarly journals Estimates of the refreezing rate in an ice-shelf borehole

2013 ◽  
Vol 59 (217) ◽  
pp. 938-948 ◽  
Author(s):  
Kenneth G. Hughes ◽  
Pat J. Langhorne ◽  
Michael J.M. Williams
Keyword(s):  
Sea Water ◽  
Salt Water ◽  
Heat Fluxes ◽  
Water Interface ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Flux Model ◽  
Thick Region ◽  
Ice Water ◽  
Heat Flux Model

AbstractThe refreezing rate of a borehole drilled through a 252 m thick region of the Ross Ice Shelf, Antarctica, is determined using oceanographic measurements over two periods of a day. We first use a method based on the conservation of salt in the supercooled salt water of the borehole. This is compared to a model using a numerical solution of the heat equation to find the temperature distribution in the host ice, allowing ice growth to be calculated from the balance of heat fluxes at the ice/water interface. This second method broadly confirms the refreezing rates deduced from salinity measurements, giving confidence in the generalization of this simple heat-flux model to predict refreezing rates of other boreholes. Predictions from both are subject to uncertainty due to the poorly defined value of the solid fraction of ice that freezes in a supercooled volume of sea water. This is taken to be 0.5 ± 0.1 throughout this study. The predicted rates are also strongly dependent on the initial and boundary conditions chosen, but results show the initial diameter of 600 mm decreases at a rate of ∼3–5 mm h−1 in an ice shelf with a minimum temperature of −22°C.

scholarly journals Characteristics of Ice Flow in Marie Byrd Land, Antarctica

1979 ◽  
Vol 24 (90) ◽  
pp. 63-75 ◽  
Author(s):  
K. E. Rose
Keyword(s):  
Flow Line ◽  
Landsat Imagery ◽  
Ice Sheet ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Streams ◽  
Ice Flow ◽  
Ross Ice Shelf ◽  
Radio Echo Sounding ◽  
Echo Sounding

AbstractExtensive radio echo-sounding has mapped the part of West Antarctica between Byrd Station, the Whitmore Mountains, the Transantarctic Mountains, and the Ross Ice Shelf. The ice sheet in this area is dominated by five major sub-parallel ice streams (A–E), which are up to 100 km wide and extend inland from the grounding line of the Ross Ice Shelf for about 400 km. Their positions have been determined by crevassing seen on radio echo-sounding records, trimetrogon photographs, and Landsat imagery. The ice streams are characterized by their flat transverse cross-sections, while the intervening ice sheet exhibits domes and ridges. Ice flow lines are defined from the ice-surface contour pattern and the trend of the ice streams. It is apparent from this work that the flow line passing through Byrd Station joins ice stream D.The bedrock of the area is relatively smooth near the Ross Ice Shelf, becoming rougher near Byrd Station and especially so near the Whitmore Mountains. Bedrock troughs, which control the positions of the ice streams, are believed to have a tectonic origin.In this paper the role of the ice streams in the glaciological regime of West Antarctica is investigated from radio-echo data and estimates of balance velocity, basal shear stress, and basal temperatures.

scholarly journals Bottom Crevasses in the Ross Ice Shelf

1975 ◽  
Vol 15 (73) ◽  
pp. 457-458 ◽  
Author(s):  
John W. Clough
Keyword(s):  
Austral Summer ◽  
Wide Angle ◽  
Velocity Measurements ◽  
Ice Shelf ◽  
Linear Features ◽  
Ross Ice Shelf ◽  
Radio Echo Sounding ◽  
Echo Sounding

Bottom crevasses were detected at many locations in the southern portion of the Ross Ice Shelf during the 1973-74 austral summer. The crevasses which extended up about 100 m from the bottom of the shelf were detected by radio-echo sounding. These linear features were mapped in some detail at the RISP Camp. Wide-angle reflection velocity measurements, airborne radio-echo sounding, and other results of the R1GGS program will be included in the discussion.

Radio Echo Determination of Basal Roughness Characteristics on the Ross Ice Shelf

1982 ◽  
Vol 3 ◽  
pp. 216-221 ◽  
Author(s):  
C. S. Neal
Keyword(s):  
Radar Signal ◽  
Bottom Surface ◽  
Small Scale ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Radio Echo Sounding ◽  
Scale Roughness ◽  
Echo Sounder ◽  
Echo Sounding

The small-scale roughness characteristics of the bottom surface of the Ross Ice Shelf (RIS) are determined at two locations using airborne radio echo-sounding results. Small-scale roughness is not resolvable by an echo sounder, but may be quantified by examination of the fading pattern of the received echo. A full interpretation of the bottom echo requires a knowledge of the modulation imposed upon the radar signal by the ice/air boundary. This is obtained by determining the roughness scales of the ice-shelf surface. Its effect on estimates of basal roughness is investigated and is found to be unimportant in most cases.

scholarly journals Characteristics of Ice Flow in Marie Byrd Land, Antarctica

1979 ◽  
Vol 24 (90) ◽  
pp. 63-75 ◽  
Author(s):  
K. E. Rose
Keyword(s):  
Flow Line ◽  
Landsat Imagery ◽  
Ice Sheet ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Streams ◽  
Ice Flow ◽  
Ross Ice Shelf ◽  
Radio Echo Sounding ◽  
Echo Sounding

AbstractExtensive radio echo-sounding has mapped the part of West Antarctica between Byrd Station, the Whitmore Mountains, the Transantarctic Mountains, and the Ross Ice Shelf. The ice sheet in this area is dominated by five major sub-parallel ice streams (A–E), which are up to 100 km wide and extend inland from the grounding line of the Ross Ice Shelf for about 400 km. Their positions have been determined by crevassing seen on radio echo-sounding records, trimetrogon photographs, and Landsat imagery. The ice streams are characterized by their flat transverse cross-sections, while the intervening ice sheet exhibits domes and ridges. Ice flow lines are defined from the ice-surface contour pattern and the trend of the ice streams. It is apparent from this work that the flow line passing through Byrd Station joins ice stream D.The bedrock of the area is relatively smooth near the Ross Ice Shelf, becoming rougher near Byrd Station and especially so near the Whitmore Mountains. Bedrock troughs, which control the positions of the ice streams, are believed to have a tectonic origin.In this paper the role of the ice streams in the glaciological regime of West Antarctica is investigated from radio-echo data and estimates of balance velocity, basal shear stress, and basal temperatures.

scholarly journals Radio Echo Determination of Basal Roughness Characteristics on the Ross Ice Shelf

1982 ◽  
Vol 3 ◽  
pp. 216-221 ◽  
Author(s):  
C. S. Neal
Keyword(s):  
Radar Signal ◽  
Bottom Surface ◽  
Small Scale ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Radio Echo Sounding ◽  
Scale Roughness ◽  
Echo Sounder ◽  
Echo Sounding

The small-scale roughness characteristics of the bottom surface of the Ross Ice Shelf (RIS) are determined at two locations using airborne radio echo-sounding results. Small-scale roughness is not resolvable by an echo sounder, but may be quantified by examination of the fading pattern of the received echo. A full interpretation of the bottom echo requires a knowledge of the modulation imposed upon the radar signal by the ice/air boundary. This is obtained by determining the roughness scales of the ice-shelf surface. Its effect on estimates of basal roughness is investigated and is found to be unimportant in most cases.

scholarly journals Bottom Crevasses in the Ross Ice Shelf

1975 ◽  
Vol 15 (73) ◽  
pp. 457-458
Author(s):  
John W. Clough
Keyword(s):  
Austral Summer ◽  
Wide Angle ◽  
Velocity Measurements ◽  
Ice Shelf ◽  
Linear Features ◽  
Ross Ice Shelf ◽  
Radio Echo Sounding ◽  
Echo Sounding

Bottom crevasses were detected at many locations in the southern portion of the Ross Ice Shelf during the 1973-74 austral summer. The crevasses which extended up about 100 m from the bottom of the shelf were detected by radio-echo sounding. These linear features were mapped in some detail at the RISP Camp. Wide-angle reflection velocity measurements, airborne radio-echo sounding, and other results of the R1GGS program will be included in the discussion.

scholarly journals Tabular Icebergs: Implication from Geophysical Studies of Ice Shelves

1980 ◽  
Vol 1 ◽  
pp. 55-55
Author(s):  
Sion Shabtaie ◽  
Charles R. Bentley
Keyword(s):  
Mass Balance ◽  
Sea Water ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Frictional Drag ◽  
Ice Shelves ◽  
Ross Ice Shelf ◽  
Rift Zones ◽  
Different Characteristics ◽  
Ice Water

Recent geophysical and glaciological investigations of the Ross Ice Shelf have revealed many complexities in the ice shelf that can be important factors in iceberg structure. The presence of rift zones, surface and bottom crevasses, corrugations, ridges and troughs, and other features could substantially modify the hydraulics of iceberg towing and lead to disintegration of the berg in the course of transport.The relationships between the elevation above sea-level and total ice thickness for three ice shelves (Ross, Brunt, and McMurdo) are given; from them, expressions for the thickness/freeboard ratios of tabular icebergs calved from these ice shelves are obtained. The relationships obtained from the measured values of surface elevation and ice thickness are in agreement with models derived assuming hydrostatic equilibrium.Areas of brine infiltration into the Ross Ice Shelf have been mapped. Examples of radar profiles in these zones are shown. Absorption from the brine layers results in a poor or absent bottom echo. It is probable that little saline ice exists at the bottom of the Ross Ice Shelf front due to a rapid bottom melting near the ice front, and that the thickness of the saline ice at the bottom of icebergs calving from the Ross Ice Shelf is no more than a few meters, if there is any at all.We have observed many rift zones on the ice shelf by airborne radar techniques, and at one site the bottom and surface topographies of (buried) rift zones have been delineated. These rift zones play an obvious role in iceberg formation and may also affect the dynamics of iceberg transport. Bottom crevasses with different shapes, sizes, and spacings are abundant in ice shelves; probably some are filled with saline ice and others with unfrozen sea-water. Existence of these bottom crevasses could lead to a rapid disintegration of icebergs in the course of transport, as well as increasing the frictional drag at the ice-water boundary.Radar profiles of the ice-shelf barrier at four sites in flow bands of very different characteristics are shown. In some places rifting upstream from the barrier shows regular spacings, suggesting a periodic calving. Differential bottom melting near the barrier causes the icebergs to have an uneven surface and bottom (i.e. dome-shaped).Electrical resistivity soundings on the ice shelf can be applied to estimate the temperature-depth function, and from that the basal mass-balance rate. With some modifications, the technique may also be applied to estimating the basal mass-balance rates of tabular icebergs.

scholarly journals Tabular Icebergs: Implications from Geophysical Studies of Ice Shelves

1982 ◽  
Vol 28 (100) ◽  
pp. 413-430 ◽  
Author(s):  
Sion Shabtaie ◽  
Charles R. Bentley
Keyword(s):  
Mass Balance ◽  
Sea Water ◽  
Ice Thickness ◽  
Ice Shelf ◽  
Frictional Drag ◽  
Ice Shelves ◽  
Ross Ice Shelf ◽  
Rift Zones ◽  
Different Characteristics ◽  
Ice Water

AbstractRecent geophysical and glaciological investigations of the Ross Ice Shelf have revealed many complexities in the ice shelf that can be important factors in iceberg structure. The presence of rift zones, surface and bottom crevasses, corrugations, ridge/troughs, and other features could substantially modify the hydraulics of iceberg towing and lead to disintegration in the course of transport.The relationships between the elevation above sea-level and total ice thickness for three ice shelves (Ross, Brunt, and McMurdo) are given; from them, expressions for the thickness/freeboard ratios of tabular icebergs calved from these ice shelves are obtained. The relationships obtained from the measured values of surface elevation and ice thickness are in agreement with models derived assuming hydrostatic equilibrium.Areas of brine infiltration into the Ross Ice Shelf have been mapped. Examples of radar profiles in these zones are shown. Absorption from the brine layers results in a poor or absent bottom echo. It is probable that little saline ice exists at the bottom of the Ross Ice Shelf front due to a rapid bottom melting near the ice front, and that the thickness of the saline ice at the bottom of icebergs calving from the Ross Ice Shelf is no more than a few meters, if there is any at all.We have observed many rift zones on the ice shelf by airborne radar techniques, and at one site the bottom and surface topographies of (buried) rift zones have been delineated. These rift zones play an obvious role in iceberg formation and may also affect the dynamics of iceberg transport. Bottom crevasses with different shapes, sizes, and spacings are abundant in ice shelves; probably some are filled with saline ice and others with unfrozen sea-water. Existence of these bottom crevasses could lead to a rapid disintegration of icebergs in the course of transport, as well as increasing the frictional drag at the ice-water boundary.Radar profiles of the ice shelf front at four sites in flow bands of very different characteristics are shown. In some places rifting up-stream from the front shows regular spacings, suggesting a periodic calving. Differential bottom melting near the front causes the icebergs to have an uneven surface and bottom (i.e. dome shaped).Electrical resistivity soundings on the ice shelf can be applied to estimate the temperature-depth function, and from that the basal mass-balance rate. With some modifications, the technique may also be applied to estimating the basal mass balance rates of tabular icebergs.

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