A Comparison Between Derived Internal Dielectric Properties and Radio-Echo Sounding Records of the Ice Sheet at Cape Folger, Antarctica
The use of radio-echo sounding records to indicate the presence of internal layers within large ice sheets is of interest to glaciologists because it offers a means of tracking the internal properties of the ice sheets over large distances. The interpretation of the reflections obtained in this mann...
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ftdtic:ADA055245 2023-05-15T13:35:39+02:00 A Comparison Between Derived Internal Dielectric Properties and Radio-Echo Sounding Records of the Ice Sheet at Cape Folger, Antarctica Keliher,T E Ackley,S F COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER N H 1978-04 text/html http://www.dtic.mil/docs/citations/ADA055245 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA055245 en eng http://www.dtic.mil/docs/citations/ADA055245 APPROVED FOR PUBLIC RELEASE DTIC AND NTIS Snow Ice and Permafrost Acoustics Electricity and Magnetism *DIELECTRIC PROPERTIES *ICE *ACOUSTIC PROPERTIES DENSITY LAYERS DEFORMATION REFLECTION GLACIOLOGY INTERNAL ECHO RANGING ANTARCTIC REGIONS COLD WEATHER TESTS SOUNDING Cape Folger PE61102A WU002 AST24 Text 1978 ftdtic 2016-02-20T13:10:46Z The use of radio-echo sounding records to indicate the presence of internal layers within large ice sheets is of interest to glaciologists because it offers a means of tracking the internal properties of the ice sheets over large distances. The interpretation of the reflections obtained in this manner is more valuable, however, if a physical property change relating to the glaciological regime can be related to the dielectric property change producing the radio-echo reflections. In this report, we use the measured physical properties of core to bedrock taken at Cape Folger, East Antarctica (66 deg 22 min s, 111 deg (E), 324-m depth), to compute a profile of dielectric properties and from this, a depth-reflection coefficient profile for comparison with observed radio-echo reflections. The measurements available on physical properties are: density variations, bubble size and shape changes, and crystal fabric variations. The depths of the strong reflections shown on the available radio-echo records are in reasonable agreement with the depths corresponding to the highest reflection coefficients computed from the combined physical property measurements. In calculations to differentiate the separate effects of different physical properties, it appears that density variations account for the primary contributions to the calculated dielectric property changes corresponding to the highest reflection coefficients. However, bubble changes alone can also account for reasonable, though lower, reflection coefficients at the appropriate depths. Crystal fabric variations correspond poorly with the reflection locations. Density variations are normally associated with depositional events in the history of the ice sheet. Text Antarc* Antarctic Antarctica East Antarctica Ice Ice Sheet permafrost Defense Technical Information Center: DTIC Technical Reports database Antarctic Cape Folger ENVELOPE(110.745,110.745,-66.131,-66.131) East Antarctica Folger ENVELOPE(110.745,110.745,-66.131,-66.131) |
institution |
Open Polar |
collection |
Defense Technical Information Center: DTIC Technical Reports database |
op_collection_id |
ftdtic |
language |
English |
topic |
Snow Ice and Permafrost Acoustics Electricity and Magnetism *DIELECTRIC PROPERTIES *ICE *ACOUSTIC PROPERTIES DENSITY LAYERS DEFORMATION REFLECTION GLACIOLOGY INTERNAL ECHO RANGING ANTARCTIC REGIONS COLD WEATHER TESTS SOUNDING Cape Folger PE61102A WU002 AST24 |
spellingShingle |
Snow Ice and Permafrost Acoustics Electricity and Magnetism *DIELECTRIC PROPERTIES *ICE *ACOUSTIC PROPERTIES DENSITY LAYERS DEFORMATION REFLECTION GLACIOLOGY INTERNAL ECHO RANGING ANTARCTIC REGIONS COLD WEATHER TESTS SOUNDING Cape Folger PE61102A WU002 AST24 Keliher,T E Ackley,S F A Comparison Between Derived Internal Dielectric Properties and Radio-Echo Sounding Records of the Ice Sheet at Cape Folger, Antarctica |
topic_facet |
Snow Ice and Permafrost Acoustics Electricity and Magnetism *DIELECTRIC PROPERTIES *ICE *ACOUSTIC PROPERTIES DENSITY LAYERS DEFORMATION REFLECTION GLACIOLOGY INTERNAL ECHO RANGING ANTARCTIC REGIONS COLD WEATHER TESTS SOUNDING Cape Folger PE61102A WU002 AST24 |
description |
The use of radio-echo sounding records to indicate the presence of internal layers within large ice sheets is of interest to glaciologists because it offers a means of tracking the internal properties of the ice sheets over large distances. The interpretation of the reflections obtained in this manner is more valuable, however, if a physical property change relating to the glaciological regime can be related to the dielectric property change producing the radio-echo reflections. In this report, we use the measured physical properties of core to bedrock taken at Cape Folger, East Antarctica (66 deg 22 min s, 111 deg (E), 324-m depth), to compute a profile of dielectric properties and from this, a depth-reflection coefficient profile for comparison with observed radio-echo reflections. The measurements available on physical properties are: density variations, bubble size and shape changes, and crystal fabric variations. The depths of the strong reflections shown on the available radio-echo records are in reasonable agreement with the depths corresponding to the highest reflection coefficients computed from the combined physical property measurements. In calculations to differentiate the separate effects of different physical properties, it appears that density variations account for the primary contributions to the calculated dielectric property changes corresponding to the highest reflection coefficients. However, bubble changes alone can also account for reasonable, though lower, reflection coefficients at the appropriate depths. Crystal fabric variations correspond poorly with the reflection locations. Density variations are normally associated with depositional events in the history of the ice sheet. |
author2 |
COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER N H |
format |
Text |
author |
Keliher,T E Ackley,S F |
author_facet |
Keliher,T E Ackley,S F |
author_sort |
Keliher,T E |
title |
A Comparison Between Derived Internal Dielectric Properties and Radio-Echo Sounding Records of the Ice Sheet at Cape Folger, Antarctica |
title_short |
A Comparison Between Derived Internal Dielectric Properties and Radio-Echo Sounding Records of the Ice Sheet at Cape Folger, Antarctica |
title_full |
A Comparison Between Derived Internal Dielectric Properties and Radio-Echo Sounding Records of the Ice Sheet at Cape Folger, Antarctica |
title_fullStr |
A Comparison Between Derived Internal Dielectric Properties and Radio-Echo Sounding Records of the Ice Sheet at Cape Folger, Antarctica |
title_full_unstemmed |
A Comparison Between Derived Internal Dielectric Properties and Radio-Echo Sounding Records of the Ice Sheet at Cape Folger, Antarctica |
title_sort |
comparison between derived internal dielectric properties and radio-echo sounding records of the ice sheet at cape folger, antarctica |
publishDate |
1978 |
url |
http://www.dtic.mil/docs/citations/ADA055245 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA055245 |
long_lat |
ENVELOPE(110.745,110.745,-66.131,-66.131) ENVELOPE(110.745,110.745,-66.131,-66.131) |
geographic |
Antarctic Cape Folger East Antarctica Folger |
geographic_facet |
Antarctic Cape Folger East Antarctica Folger |
genre |
Antarc* Antarctic Antarctica East Antarctica Ice Ice Sheet permafrost |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica Ice Ice Sheet permafrost |
op_source |
DTIC AND NTIS |
op_relation |
http://www.dtic.mil/docs/citations/ADA055245 |
op_rights |
APPROVED FOR PUBLIC RELEASE |
_version_ |
1766068455274971136 |