scholarly journals Investigation of Sub-Ice Bedrock Characteristics by Radio-Echo Sounding

1975 ◽  
Vol 15 (73) ◽  
pp. 75-87 ◽  
Author(s):  
G. K. A. Oswald
Keyword(s):  
Surface Characteristics ◽  
Bottom Surface ◽  
Small Scale ◽  
Devon Island ◽  
Quantitative Studies ◽  
Base Camp ◽  
Surface Slopes ◽  
Radio Echo Sounding ◽  
Basal Melting ◽  
Echo Sounding

AbstractQualitative inspection of the results of the 1971/72 S.P.R.I.-N.S.F. Antarctic radio-echo sounding programme shows that it is possible to infer some characteristics of the lower face of the ice from the form of received echoes. We confirm the existence of lakes of liquid water beneath the east Antarctic ice by inspection of the top and bottom surface gradients of the ice, and suggest that basal melting occurs over a wide area in this region.Quantitative studies in Devon Island indicate that small-scale irregularities in the bedrock are characterized by slopes of about 1: 40, with some higher gradients present, possibly indicating the presence of morainal boulders. We deduce that a geological boundary was crossed between 25 and 40 km west of the base camp, the rock to the west of the boundary having lower permittivity, and higher surface slopes than that to the east.The question of the usefulness of the spatial fading of the echo in deducing surface characteristics is briefly discussed. We conclude that measurements of the fading are indeed useful, especially in the case of echoes with short “tails”.

scholarly journals Investigation of Sub-Ice Bedrock Characteristics by Radio-Echo Sounding

1975 ◽  
Vol 15 (73) ◽  
pp. 75-87 ◽  
Author(s):  
G. K. A. Oswald
Keyword(s):  
Surface Characteristics ◽  
Bottom Surface ◽  
Small Scale ◽  
Devon Island ◽  
Quantitative Studies ◽  
Base Camp ◽  
Surface Slopes ◽  
Radio Echo Sounding ◽  
Basal Melting ◽  
Echo Sounding

Abstract Qualitative inspection of the results of the 1971/72 S.P.R.I.-N.S.F. Antarctic radio-echo sounding programme shows that it is possible to infer some characteristics of the lower face of the ice from the form of received echoes. We confirm the existence of lakes of liquid water beneath the east Antarctic ice by inspection of the top and bottom surface gradients of the ice, and suggest that basal melting occurs over a wide area in this region. Quantitative studies in Devon Island indicate that small-scale irregularities in the bedrock are characterized by slopes of about 1: 40, with some higher gradients present, possibly indicating the presence of morainal boulders. We deduce that a geological boundary was crossed between 25 and 40 km west of the base camp, the rock to the west of the boundary having lower permittivity, and higher surface slopes than that to the east. The question of the usefulness of the spatial fading of the echo in deducing surface characteristics is briefly discussed. We conclude that measurements of the fading are indeed useful, especially in the case of echoes with short “tails”.

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 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 Basal Mass Balance Along a Flow Line on Ronne Ice Shelf, Antarctica (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 201
Author(s):  
A. Jenkins ◽  
C.S.M. Doake
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
Flow Line ◽  
Average Rate ◽  
Ice Shelf ◽  
Grounding Line ◽  
Radio Echo Sounding ◽  
State Models ◽  
Basal Melting ◽  
Echo Sounding

Recent glaciological work on Ronne Ice Shelf has focused on an assumed flow line which extends from Rutford Ice Stream grounding line to the ice front. Results from doppler satellite surveying and radio echo-sounding are used in kinematic calculations to determine the basal mass balance, assuming the flow line to be in a steady state. Models suggest that basal melting dominates over most of the flow line and is most pronounced at the extremities. In the region within 300 km of the grounding line and over the final 45 km before the ice front, at least 1 m/a on average must melt away to maintain the observed velocity and thickness profile. More gentle melting occurs over about half the remaining distance, but in a region between 130 and 300 km in from the ice front, basal freezing must occur at an average rate of about 0.1 m/a to maintain a steady state. The existence of a thin layer of saline ice underlying the ice shelf, which persists for a further 80 km down-stream before being melted away entirely, is consistent with the weak returns observed during both airborne and ground-based radio echo-sounding in this region.

scholarly journals Basal Mass Balance Along a Flow Line on Ronne Ice Shelf, Antarctica (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 201-201
Author(s):  
A. Jenkins ◽  
C.S.M. Doake
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
Flow Line ◽  
Average Rate ◽  
Ice Shelf ◽  
Grounding Line ◽  
Radio Echo Sounding ◽  
State Models ◽  
Basal Melting ◽  
Echo Sounding

Recent glaciological work on Ronne Ice Shelf has focused on an assumed flow line which extends from Rutford Ice Stream grounding line to the ice front. Results from doppler satellite surveying and radio echo-sounding are used in kinematic calculations to determine the basal mass balance, assuming the flow line to be in a steady state. Models suggest that basal melting dominates over most of the flow line and is most pronounced at the extremities. In the region within 300 km of the grounding line and over the final 45 km before the ice front, at least 1 m/a on average must melt away to maintain the observed velocity and thickness profile. More gentle melting occurs over about half the remaining distance, but in a region between 130 and 300 km in from the ice front, basal freezing must occur at an average rate of about 0.1 m/a to maintain a steady state. The existence of a thin layer of saline ice underlying the ice shelf, which persists for a further 80 km down-stream before being melted away entirely, is consistent with the weak returns observed during both airborne and ground-based radio echo-sounding in this region.

scholarly journals The newly developed airborne radio-echo sounding system of the AWI as a glaciological tool

1999 ◽  
Vol 29 ◽  
pp. 231-238 ◽  
Author(s):  
U. Nixdorf ◽  
D. Steinhage ◽  
U. Meyer ◽  
L. Hempel ◽  
M. Jenett ◽  
...  
Keyword(s):  
Digital Data ◽  
Radar Signal ◽  
Ice Shelves ◽  
System Sensitivity ◽  
Ice Caps ◽  
Radio Echo Sounding ◽  
Recorded Data ◽  
Along Track ◽  
Echo Sounding

AbstractSince 1994 the Alfred Wegener Institute (AWI) has operated an airborne radio-echo sounding system for remote-sensing studies of the polar ice caps in Antarctica and in Greenland. It is used to map ice thicknesses and internal layernigs of glaciers, ice sheets and ice shelves, and is capable of penetrating ice thicknesses of up to 4 km. The system was designed and built by AWI in cooperation with Aerodata Flugmeßtechnik GmbH, Technische Umversitat Hamburg-Harburg and the Deutsches Zentrum fur Luft- und Raumfahrt e.V. The system uses state-of-the-art techniques, and results in high vertical (5 m) as well as along-track (3.25 m) resolution. The radar signal is a 150 MHz burst with a duration of 60 or 600 ns. The peak power is 1.6 kW, and the system sensitivity is 190 dB. The short backfire principle has been adopted and optimized for antennae used on Polar2, a Dormer 228-100 aircraft, resulting in an antenna gain of 14 dB each. Digital data recording allows further processing. The quality of the recorded data can be monitored on screen and as online analogue plots during the flight.

scholarly journals Characterizing near-surface firn using the scattered signal component of the glacier surface return from airborne radio-echo sounding

2016 ◽  
Vol 43 (24) ◽  
pp. 12,502-12,510 ◽  
Author(s):  
Anja Rutishauser ◽  
Cyril Grima ◽  
Martin Sharp ◽  
Donald D. Blankenship ◽  
Duncan A. Young ◽  
...  
Keyword(s):  
Scattered Signal ◽  
Glacier Surface ◽  
Near Surface ◽  
Signal Component ◽  
Radio Echo Sounding ◽  
Echo Sounding

scholarly journals Forty-seven new subglacial lakes in the 0–110° E sector of East Antarctica

2007 ◽  
Vol 53 (181) ◽  
pp. 289-297 ◽  
Author(s):  
Sergey V. Popov ◽  
Valery N. Masolov
Keyword(s):  
Heat Flux ◽  
Scientific Work ◽  
East Antarctica ◽  
Lake Area ◽  
Geothermal Heat ◽  
Subglacial Lake ◽  
Deep Faults ◽  
Radio Echo Sounding ◽  
Subglacial Lakes ◽  
Echo Sounding

AbstractDuring the summer field seasons of 1987–91, studies of central East Antarctica by airborne radio-echo sounding commenced. This scientific work continued in the 1990s in the Vostok Subglacial Lake area and along the traverse route from Mirny, and led to the discovery of 16 new subglacial water cavities in the areas of Domes Fuji and Argus and the Prince Charles Mountains. Twenty-nine subglacial water cavities were revealed in the area near Vostok, along with a feature we believe to be a subglacial river. Two subglacial lakes were discovered along the Mirny–Vostok traverse route. These are located 50 km north of Komsomolskaya station and under Pionerskaya station. We find high geothermal heat flux in the vicinity of the largest of the subglacial lakes, and suggest this may be due to their location over deep faults where additional mantle heat is available.

scholarly journals Distribution of Reflected Power From the Bed by Radio Echo-Sounding in the Shirase Glacier Drainage Area, East Dronning Maud Land, Antarctica

1989 ◽  
Vol 12 ◽  
pp. 124-126
Author(s):  
Hirokazu Ohmae ◽  
Fumihiko Nishio ◽  
Shinji Mae
Keyword(s):  
Drainage Basin ◽  
Ice Sheet ◽  
Ice Flow ◽  
Boundary Area ◽  
Radio Echo Sounding ◽  
Dronning Maud Land ◽  
Reflected Power ◽  
Basal Shear ◽  
Reflection Intensity ◽  
Echo Sounding

A large part of the area of the Shirase Glacier drainage basin has been surveyed by airborne (operating frequency: 179 MHz) and ground-based (60 MHz) radio echo-sounding to define the bedrock topography and to investigate the condition of bed/ice interface since 1982.It is shown that the reflection intensity from the bed, which is corrected for attenuation in the ice sheet, has a higher value for reflection intensity in the down-stream area of Shirase Glacier than in the up-stream area. The area of strongest intensity of reflection from the bed coincides with the area for which the calculated temperature at the bed is above −1°C. The boundary area between the highest and lowest values of corrected reflected intensity corresponds to the area of decreasing basal shear stress. It is found that the distribution of high corrected reflection intensity corresponds to the area of thinning of the ice sheet, which has been measured by ice-flow observation in the Shirase Glacier drainage basin.

scholarly journals Refraction Correction for Radio Echo-Sounding of Ice Overlain by Firn

1986 ◽  
Vol 32 (111) ◽  
pp. 192-194 ◽  
Author(s):  
L. A. Rasmussen
Keyword(s):  
Refractive Index ◽  
Explicit Solutions ◽  
Exact Formulation ◽  
Mass Thickness ◽  
Radio Echo Sounding ◽  
Echo Sounding

AbstractRadio-echo signals travel faster in firn than in ice, which affects the analysis of ice-mass thickness. If this effect is neglected, then the calculated thickness of an ice mass may be in error by an amount of the order of one-tenth of the firn thickness. An exact formulation is derived for the path of the signal through the firn and the ice. Explicit solutions are given for constant, linear, and quadratic profiles of the refractive index in the firn layer.

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