scholarly journals Radio Echo Sounding of Horizontal Layers in Ice

1973 ◽  
Vol 12 (66) ◽  
pp. 383-397 ◽  
Author(s):  
C. H. Harrison
Keyword(s):  
Dielectric Constant ◽  
Reflection Coefficient ◽  
Ice Crystals ◽  
Fractional Change ◽  
Dielectric Absorption ◽  
Radio Echo Sounding ◽  
The Antarctic ◽  
Horizontal Layers ◽  
Effective Reflection Coefficient ◽  
Echo Sounding

Radio echo-sounding surveys of Antarctica and Greenland have revealed extensive layering within the ice. Formulae for the effective reflection coefficient, when viewed by a pulsed radar, are derived for isolated or multiple randomly spaced layers. In the latter case the variation in dielectric constant with depth is described by a vertical autocorrelation function and a standard deviation. Some measurements of the reflection coefficient of layers, and the dielectric absorption of ice are given. The significance of the fading of layer echoes and the possible causes of variations in the dielectric constant are considered and some further investigations are suggested. It is concluded that the echo strengths found in the Antarctic may be explained by multiple layering, and that the necessary fractional change in the dielectric constant may be as small as 10−4. It is suggested that this change in dielectric constant may be due to differences in orientation of anisotropic ice crystals.

scholarly journals Radio Echo Sounding of Horizontal Layers in Ice

1973 ◽  
Vol 12 (66) ◽  
pp. 383-397 ◽  
Author(s):  
C. H. Harrison
Keyword(s):  
Dielectric Constant ◽  
Reflection Coefficient ◽  
Ice Crystals ◽  
Fractional Change ◽  
Dielectric Absorption ◽  
Radio Echo Sounding ◽  
The Antarctic ◽  
Horizontal Layers ◽  
Effective Reflection Coefficient ◽  
Echo Sounding

Radio echo-sounding surveys of Antarctica and Greenland have revealed extensive layering within the ice. Formulae for the effective reflection coefficient, when viewed by a pulsed radar, are derived for isolated or multiple randomly spaced layers. In the latter case the variation in dielectric constant with depth is described by a vertical autocorrelation function and a standard deviation. Some measurements of the reflection coefficient of layers, and the dielectric absorption of ice are given. The significance of the fading of layer echoes and the possible causes of variations in the dielectric constant are considered and some further investigations are suggested.It is concluded that the echo strengths found in the Antarctic may be explained by multiple layering, and that the necessary fractional change in the dielectric constant may be as small as 10−4. It is suggested that this change in dielectric constant may be due to differences in orientation of anisotropic ice crystals.

scholarly journals Dielectric Variability of a 130 m Antarctic Ice Core: Implications for Radar Sounding

1988 ◽  
Vol 11 ◽  
pp. 95-99 ◽  
Author(s):  
J. C. Moore
Keyword(s):  
Reflection Coefficient ◽  
Smooth Function ◽  
High Frequency ◽  
Ice Core ◽  
Ice Sheets ◽  
Layer Model ◽  
Polar Ice ◽  
Radio Echo Sounding ◽  
Polar Ice Sheets ◽  
Echo Sounding

A 130 m long ice core has been dielectrically profiled. From an analysis of the measurements, we obtain a profile of the high-frequency (radio-echo) conductivity. This profile has been represented by a simplified 700 layer model. The model has layers of differing conductivities, permittivities and thicknesses. A reflection-coefficient log can be calculated, assuming that permittivity is a smooth function of depth. Variations in conductivity are shown to be more likely sources of internal reflections from depths greater than a few hundred metres than changes in permittivity caused by density changes. The log is convoluted with input pulses of various frequencies and pulse lengths in order to produce synthetic radargrams. These show features that correspond to the internal reflections typically seen when radio echo-sounding polar ice sheets.

scholarly journals Acidity Levels in Ice Sheets from Radio Echo-Sounding

1982 ◽  
Vol 3 ◽  
pp. 199-203 ◽  
Author(s):  
D. H. M. Millar
Keyword(s):  
Reflection Coefficient ◽  
Volcanic Activity ◽  
Acid Content ◽  
Ice Sheets ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Depth Profiles ◽  
Radio Echo Sounding ◽  
Large Volcanic Eruptions ◽  
Echo Sounding

It has been suggested (Hammer 1977, Gudmandsen and Overgaard 1978, Millar 1981) that layers of acidic ice, formed after large volcanic eruptions, are a cause of radio echo layering. The power reflection coefficient (PRO of these reflecting layers may be related to their acid content and thickness. The present paper makes estimates of ice acidity from radio echo-sounding (RES) and compares them with measured values along Greenland ice cores. Dated Antarctic PRC/depth profiles are also presented, and acidity estimates made which give a crude indication of past volcanic activity in the southern hemisphere to ~150 ka BP.

scholarly journals Latest improvements for the echo sounding system of the Italian radar glaciological group and measurements in Antarctica

1999 ◽  
Vol 42 (2) ◽  
Author(s):  
I. E. Tabacco ◽  
C. Bianchi ◽  
M. Chiappini ◽  
A. Passerini ◽  
A. Zirizzotti ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Electromagnetic Wave ◽  
Acquisition System ◽  
Vertical Resolution ◽  
Antarctic Expedition ◽  
Radio Echo Sounding ◽  
The Antarctic ◽  
System Operating ◽  
New System ◽  
Echo Sounding

Radio echo sounding is an active remote-sensing method using electromagnetic wave penetration in a particular medium such as ice and permits the measurements of its thickness, the level of the bedrock and inhomogeneities i.e. of the internal layering of glaciers. The Italian Radar Glaciological Group has implemented technical improvements on the system operating during the 1995-1996 Antarctic expeditions, increasing the horizontal and the vertical resolution by means of a new acquisition ensemble. The new system was used during the Antarctic expedition in 1997-1998. The present paper presents the latest improvements of the radar acquisition system and radar profiles extracted from the 1995-1996 and the 1997-1998 Antarctic expeditions are presented.

scholarly journals Dielectric Variability of a 130 m Antarctic Ice Core: Implications for Radar Sounding

1988 ◽  
Vol 11 ◽  
pp. 95-99 ◽  
Author(s):  
J. C. Moore
Keyword(s):  
Reflection Coefficient ◽  
Smooth Function ◽  
High Frequency ◽  
Ice Core ◽  
Ice Sheets ◽  
Layer Model ◽  
Polar Ice ◽  
Radio Echo Sounding ◽  
Polar Ice Sheets ◽  
Echo Sounding

A 130 m long ice core has been dielectrically profiled. From an analysis of the measurements, we obtain a profile of the high-frequency (radio-echo) conductivity. This profile has been represented by a simplified 700 layer model. The model has layers of differing conductivities, permittivities and thicknesses. A reflection-coefficient log can be calculated, assuming that permittivity is a smooth function of depth. Variations in conductivity are shown to be more likely sources of internal reflections from depths greater than a few hundred metres than changes in permittivity caused by density changes. The log is convoluted with input pulses of various frequencies and pulse lengths in order to produce synthetic radargrams. These show features that correspond to the internal reflections typically seen when radio echo-sounding polar ice sheets.

scholarly journals Acidity Levels in Ice Sheets from Radio Echo-Sounding

1982 ◽  
Vol 3 ◽  
pp. 199-203 ◽  
Author(s):  
D. H. M. Millar
Keyword(s):  
Reflection Coefficient ◽  
Volcanic Activity ◽  
Acid Content ◽  
Ice Sheets ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Depth Profiles ◽  
Radio Echo Sounding ◽  
Large Volcanic Eruptions ◽  
Echo Sounding

It has been suggested (Hammer 1977, Gudmandsen and Overgaard 1978, Millar 1981) that layers of acidic ice, formed after large volcanic eruptions, are a cause of radio echo layering. The power reflection coefficient (PRO of these reflecting layers may be related to their acid content and thickness. The present paper makes estimates of ice acidity from radio echo-sounding (RES) and compares them with measured values along Greenland ice cores. Dated Antarctic PRC/depth profiles are also presented, and acidity estimates made which give a crude indication of past volcanic activity in the southern hemisphere to ~150 ka BP.

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
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