Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns
Abstract Airborne radio echo-sounding of Spitsbergen glaciers during 1980 used 60 MHz SPR1 Mk IV equipment. On several glaciers results showed unambiguous bottom returns at depths 2–3 times those reported in previous Soviet echo-sounding at 440 and 620 MHz. Comparison of 60 MHZ records and independe...
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1984
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Online Access: | http://dx.doi.org/10.1017/s0022143000008431 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008431 |
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crcambridgeupr:10.1017/s0022143000008431 2024-03-03T08:45:19+00:00 Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns Dowdeswell, J. A. Drewry, D.J. Liestøl, O. Orheim, O. 1984 http://dx.doi.org/10.1017/s0022143000008431 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008431 en eng Cambridge University Press (CUP) Journal of Glaciology volume 30, issue 104, page 16-21 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1984 crcambridgeupr https://doi.org/10.1017/s0022143000008431 2024-02-08T08:41:37Z Abstract Airborne radio echo-sounding of Spitsbergen glaciers during 1980 used 60 MHz SPR1 Mk IV equipment. On several glaciers results showed unambiguous bottom returns at depths 2–3 times those reported in previous Soviet echo-sounding at 440 and 620 MHz. Comparison of 60 MHZ records and independent gravity-surveyed ice thickness for two glaciers agreed to within 10%, whereas Soviet ice thicknesses were only 30–60% of gravity depths. Soviet bed echoes often coincided closely with an internal reflecting horizon recorded by the SPRI Mk IV system, and it is shown that Soviet U.H.F. equipment failed to penetrate to the true glacier bed on a number of ice masses (e.g. Finsterwalderbreen, Kongsvegen, Negribreen). This was probably due to increased absorption and scattering at higher radio frequencies, related to the inhomogeneous nature of Spitsbergen glaciers, which are often at or near the pressure-melting point. Both 60 MHz and U.H.F. equipment seldom recorded bed echoes in ice-cap accumulation areas (e.g. Isachsenfonna), where firn soaking during summer and 10 m temperatures of zero degrees have been observed. An isolated internal reflecting horizon was recorded on many glaciers. It is unlikely to be a moraine layer, but may be related to ice with a water content of 1–2% observed at a similar depth (115 m) in a drill core from Fridtjovbreen. Article in Journal/Newspaper Ice cap Journal of Glaciology Spitsbergen Cambridge University Press Kongsvegen ENVELOPE(12.657,12.657,78.854,78.854) Finsterwalderbreen ENVELOPE(15.273,15.273,77.489,77.489) Fridtjovbreen ENVELOPE(14.450,14.450,77.830,77.830) Negribreen ENVELOPE(19.150,19.150,78.564,78.564) True Glacier ENVELOPE(-111.750,-111.750,-74.633,-74.633) Isachsenfonna ENVELOPE(13.000,13.000,79.000,79.000) Journal of Glaciology 30 104 16 21 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Dowdeswell, J. A. Drewry, D.J. Liestøl, O. Orheim, O. Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns |
topic_facet |
Earth-Surface Processes |
description |
Abstract Airborne radio echo-sounding of Spitsbergen glaciers during 1980 used 60 MHz SPR1 Mk IV equipment. On several glaciers results showed unambiguous bottom returns at depths 2–3 times those reported in previous Soviet echo-sounding at 440 and 620 MHz. Comparison of 60 MHZ records and independent gravity-surveyed ice thickness for two glaciers agreed to within 10%, whereas Soviet ice thicknesses were only 30–60% of gravity depths. Soviet bed echoes often coincided closely with an internal reflecting horizon recorded by the SPRI Mk IV system, and it is shown that Soviet U.H.F. equipment failed to penetrate to the true glacier bed on a number of ice masses (e.g. Finsterwalderbreen, Kongsvegen, Negribreen). This was probably due to increased absorption and scattering at higher radio frequencies, related to the inhomogeneous nature of Spitsbergen glaciers, which are often at or near the pressure-melting point. Both 60 MHz and U.H.F. equipment seldom recorded bed echoes in ice-cap accumulation areas (e.g. Isachsenfonna), where firn soaking during summer and 10 m temperatures of zero degrees have been observed. An isolated internal reflecting horizon was recorded on many glaciers. It is unlikely to be a moraine layer, but may be related to ice with a water content of 1–2% observed at a similar depth (115 m) in a drill core from Fridtjovbreen. |
format |
Article in Journal/Newspaper |
author |
Dowdeswell, J. A. Drewry, D.J. Liestøl, O. Orheim, O. |
author_facet |
Dowdeswell, J. A. Drewry, D.J. Liestøl, O. Orheim, O. |
author_sort |
Dowdeswell, J. A. |
title |
Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns |
title_short |
Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns |
title_full |
Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns |
title_fullStr |
Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns |
title_full_unstemmed |
Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns |
title_sort |
radio echo-sounding of spitsbergen glaciers: problems in the interpretation of layer and bottom returns |
publisher |
Cambridge University Press (CUP) |
publishDate |
1984 |
url |
http://dx.doi.org/10.1017/s0022143000008431 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008431 |
long_lat |
ENVELOPE(12.657,12.657,78.854,78.854) ENVELOPE(15.273,15.273,77.489,77.489) ENVELOPE(14.450,14.450,77.830,77.830) ENVELOPE(19.150,19.150,78.564,78.564) ENVELOPE(-111.750,-111.750,-74.633,-74.633) ENVELOPE(13.000,13.000,79.000,79.000) |
geographic |
Kongsvegen Finsterwalderbreen Fridtjovbreen Negribreen True Glacier Isachsenfonna |
geographic_facet |
Kongsvegen Finsterwalderbreen Fridtjovbreen Negribreen True Glacier Isachsenfonna |
genre |
Ice cap Journal of Glaciology Spitsbergen |
genre_facet |
Ice cap Journal of Glaciology Spitsbergen |
op_source |
Journal of Glaciology volume 30, issue 104, page 16-21 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000008431 |
container_title |
Journal of Glaciology |
container_volume |
30 |
container_issue |
104 |
container_start_page |
16 |
op_container_end_page |
21 |
_version_ |
1792500853037334528 |