Dynamics of the cold surface layer of polythermal Storglaciären, Sweden
Polythermal glaciers, i.e. glaciers with a combination of ice at and below the freezing point, are widespread in arctic and subarctic environments. The polythermal structure has major implications for glacier hydrology, ice flow and glacial erosion. However, the interplay of factors governing its sp...
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Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK)
2004
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ftstockholmuniv:oai:DiVA.org:su-161 2023-05-15T15:14:15+02:00 Dynamics of the cold surface layer of polythermal Storglaciären, Sweden Pettersson, Rickard 2004 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-161 eng eng Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK) Stockholm : Institutionen för naturgeografi och kvartärgeologi Avhandling i geografi med naturgeografisk inriktning, 1650-4992 31 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-161 urn:isbn:91-7265-907-6 info:eu-repo/semantics/openAccess polythermal glacier cold surface layer ground-penetrating radar spatial variability water content Storglaciären Earth sciences Geovetenskap Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2004 ftstockholmuniv 2023-02-23T21:38:39Z Polythermal glaciers, i.e. glaciers with a combination of ice at and below the freezing point, are widespread in arctic and subarctic environments. The polythermal structure has major implications for glacier hydrology, ice flow and glacial erosion. However, the interplay of factors governing its spatial and temporal variations such as net mass balance, ice advection and water content in the ice is poorly investigated and as yet not fully understood. This study deals with a thorough investigation of the polythermal regime on Storglaciären, northern Sweden, a small valley glacier with a cold surface layer in the ablation area. Extensive field work was performed including mapping of the cold surface layer using ground-penetrating radar, ice temperature measurements, mass balance and ice velocity measurements. Analyses of these data combined with numerical modelling were used specifically to investigate the spatial and temporal variability of the cold surface layer, the spatial distribution of the water content just below the cold surface layer transition, the effect of radar frequency on the detection of the surface layer, and the sensitivity of the cold surface layer to changes in forcing. A comparison between direct temperature measurements in boreholes and ground-penetrating surveys shows that the radar-inferred cold-temperate transition depth is within ±1 m from the melting point of ice at frequencies above ~300 MHz. At frequencies below ~155 MHz, the accuracy degrades because of reduced scattering efficiency that occurs when the scatterers become much smaller compared to the wavelength. The mapped spatial pattern of the englacial cold-temperate transition boundary is complex. This pattern reflects the observed spatial variation in net loss of ice at the surface by ablation and vertical advection of ice, which is suggested to provide the predominant forcing of the cold surface layer thickness pattern. This is further supported by thermomechanical modeling of the cold surface layer, which indicates high ... Doctoral or Postdoctoral Thesis Arctic Northern Sweden Subarctic Stockholm University: Publications (DiVA) Arctic Storglaciären ENVELOPE(18.560,18.560,67.904,67.904) |
institution |
Open Polar |
collection |
Stockholm University: Publications (DiVA) |
op_collection_id |
ftstockholmuniv |
language |
English |
topic |
polythermal glacier cold surface layer ground-penetrating radar spatial variability water content Storglaciären Earth sciences Geovetenskap |
spellingShingle |
polythermal glacier cold surface layer ground-penetrating radar spatial variability water content Storglaciären Earth sciences Geovetenskap Pettersson, Rickard Dynamics of the cold surface layer of polythermal Storglaciären, Sweden |
topic_facet |
polythermal glacier cold surface layer ground-penetrating radar spatial variability water content Storglaciären Earth sciences Geovetenskap |
description |
Polythermal glaciers, i.e. glaciers with a combination of ice at and below the freezing point, are widespread in arctic and subarctic environments. The polythermal structure has major implications for glacier hydrology, ice flow and glacial erosion. However, the interplay of factors governing its spatial and temporal variations such as net mass balance, ice advection and water content in the ice is poorly investigated and as yet not fully understood. This study deals with a thorough investigation of the polythermal regime on Storglaciären, northern Sweden, a small valley glacier with a cold surface layer in the ablation area. Extensive field work was performed including mapping of the cold surface layer using ground-penetrating radar, ice temperature measurements, mass balance and ice velocity measurements. Analyses of these data combined with numerical modelling were used specifically to investigate the spatial and temporal variability of the cold surface layer, the spatial distribution of the water content just below the cold surface layer transition, the effect of radar frequency on the detection of the surface layer, and the sensitivity of the cold surface layer to changes in forcing. A comparison between direct temperature measurements in boreholes and ground-penetrating surveys shows that the radar-inferred cold-temperate transition depth is within ±1 m from the melting point of ice at frequencies above ~300 MHz. At frequencies below ~155 MHz, the accuracy degrades because of reduced scattering efficiency that occurs when the scatterers become much smaller compared to the wavelength. The mapped spatial pattern of the englacial cold-temperate transition boundary is complex. This pattern reflects the observed spatial variation in net loss of ice at the surface by ablation and vertical advection of ice, which is suggested to provide the predominant forcing of the cold surface layer thickness pattern. This is further supported by thermomechanical modeling of the cold surface layer, which indicates high ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Pettersson, Rickard |
author_facet |
Pettersson, Rickard |
author_sort |
Pettersson, Rickard |
title |
Dynamics of the cold surface layer of polythermal Storglaciären, Sweden |
title_short |
Dynamics of the cold surface layer of polythermal Storglaciären, Sweden |
title_full |
Dynamics of the cold surface layer of polythermal Storglaciären, Sweden |
title_fullStr |
Dynamics of the cold surface layer of polythermal Storglaciären, Sweden |
title_full_unstemmed |
Dynamics of the cold surface layer of polythermal Storglaciären, Sweden |
title_sort |
dynamics of the cold surface layer of polythermal storglaciären, sweden |
publisher |
Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK) |
publishDate |
2004 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-161 |
long_lat |
ENVELOPE(18.560,18.560,67.904,67.904) |
geographic |
Arctic Storglaciären |
geographic_facet |
Arctic Storglaciären |
genre |
Arctic Northern Sweden Subarctic |
genre_facet |
Arctic Northern Sweden Subarctic |
op_relation |
Avhandling i geografi med naturgeografisk inriktning, 1650-4992 31 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-161 urn:isbn:91-7265-907-6 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766344723057868800 |