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Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques. / Alessio Gusmeroli

Swansea University Author: Alessio Gusmeroli

Abstract

Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques. Alessio Gusmeroli Submitted in June, 2010, in accordance with the requirements for the degree of PhD Swansea University, School of the Environment and Society Abstract: Geophysical experiment...

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Published: 2010
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42751
first_indexed 2018-08-02T18:55:27Z
last_indexed 2018-08-03T10:11:00Z
id cronfa42751
recordtype RisThesis
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spelling 2018-08-02T16:24:30.3517957 v2 42751 2018-08-02 Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques. 44fc65e29655f6d6525be49576889c44 NULL Alessio Gusmeroli Alessio Gusmeroli true true 2018-08-02 Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques. Alessio Gusmeroli Submitted in June, 2010, in accordance with the requirements for the degree of PhD Swansea University, School of the Environment and Society Abstract: Geophysical experiments were carried out to investigate spatial and temporal changes in the thermal regime and water-content of Storglaciaren, a polythermal glacier located in Arctic Sweden. Thermal changes were observed by mapping the englacial transition between permanently frozen (cold) and temperate ice with a ground-penetrating radar in April 2009. The 2009 map was compared with surveys acquired in 1989 and 2001. The comparison shows that the thinning of the cold layer observed between 1989 and 2001 is still ongoing. The thinning rate in the two time windows analyzed is approximately similar (~0.75 m/a). A volume calculation shows that the cold surface layer has lost one third of its volume in 20 years. Cross borehole zero offset radar profiles were employed to profile at high resolution, radar wave speed and power to ~100 m depth at three sites on the glacier. Radio wave speeds, interpreted in terms of ice water-content, show that water-content in the temperate ice of Storglaciaren is low (<1%) and homogeneous with depth in the upper part of the temperate ice. An increase of water-content due to strain- heating in the deepest part of the surveys (>70 m) was observed. Spatial variability due to complex interactions between water-content generated at the close-off and water-content produced by strain heating was observed at the three sites. Seismic refraction surveys were used to estimate seismic-wave attenuation using the spectral ratio method for energy travelling in the uppermost ice with an average temperature of approximately -1&deg;C. Attenuation values were derived between 100 and 300 Hz using the P-wave quality factor, Qp, the inverse of the internal friction. By assuming constant attenuation along the seismic line, mean Qp was 6+/-1. Qp varied from 8+/-1 to 5+/-1 from the near-offset to the far-offset region of the line, respectively. Since the wave progagates deeper at, far-offsets, this variation is interpreted by considering the temperature profile of the study area; far-offset arrivals sampled warmer and thus more-attenuative ice. E-Thesis Geophysics.;Geomorphology. 31 12 2010 2010-12-31 COLLEGE NANME Geography COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:30.3517957 2018-08-02T16:24:30.3517957 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Geography Alessio Gusmeroli NULL 1 0042751-02082018162519.pdf 10807520.pdf 2018-08-02T16:25:19.1170000 Output 33864149 application/pdf E-Thesis true 2018-08-02T16:25:19.1170000 false
title Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques.
spellingShingle Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques.
Alessio Gusmeroli
title_short Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques.
title_full Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques.
title_fullStr Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques.
title_full_unstemmed Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques.
title_sort Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques.
author_id_str_mv 44fc65e29655f6d6525be49576889c44
author_id_fullname_str_mv 44fc65e29655f6d6525be49576889c44_***_Alessio Gusmeroli
author Alessio Gusmeroli
author2 Alessio Gusmeroli
format E-Thesis
publishDate 2010
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Geography{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Geography
document_store_str 1
active_str 0
description Polythermal glacier dynamics at Storglaciaren, Arctic Sweden, inferred using in situ geophysical techniques. Alessio Gusmeroli Submitted in June, 2010, in accordance with the requirements for the degree of PhD Swansea University, School of the Environment and Society Abstract: Geophysical experiments were carried out to investigate spatial and temporal changes in the thermal regime and water-content of Storglaciaren, a polythermal glacier located in Arctic Sweden. Thermal changes were observed by mapping the englacial transition between permanently frozen (cold) and temperate ice with a ground-penetrating radar in April 2009. The 2009 map was compared with surveys acquired in 1989 and 2001. The comparison shows that the thinning of the cold layer observed between 1989 and 2001 is still ongoing. The thinning rate in the two time windows analyzed is approximately similar (~0.75 m/a). A volume calculation shows that the cold surface layer has lost one third of its volume in 20 years. Cross borehole zero offset radar profiles were employed to profile at high resolution, radar wave speed and power to ~100 m depth at three sites on the glacier. Radio wave speeds, interpreted in terms of ice water-content, show that water-content in the temperate ice of Storglaciaren is low (<1%) and homogeneous with depth in the upper part of the temperate ice. An increase of water-content due to strain- heating in the deepest part of the surveys (>70 m) was observed. Spatial variability due to complex interactions between water-content generated at the close-off and water-content produced by strain heating was observed at the three sites. Seismic refraction surveys were used to estimate seismic-wave attenuation using the spectral ratio method for energy travelling in the uppermost ice with an average temperature of approximately -1&deg;C. Attenuation values were derived between 100 and 300 Hz using the P-wave quality factor, Qp, the inverse of the internal friction. By assuming constant attenuation along the seismic line, mean Qp was 6+/-1. Qp varied from 8+/-1 to 5+/-1 from the near-offset to the far-offset region of the line, respectively. Since the wave progagates deeper at, far-offsets, this variation is interpreted by considering the temperature profile of the study area; far-offset arrivals sampled warmer and thus more-attenuative ice.
published_date 2010-12-31T19:38:46Z
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score 11.047609

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