Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography
Polar ice cores act as a unique archive of the Earth’s climate system. However, due to logistic constraints, the representativity of these ice-core records cannot be estimated directly. One possible remedy is to analyze the spatial variability in polar snow and firn and combine the results with an i...
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ftawi:oai:epic.awi.de:47495 2024-09-15T17:46:27+00:00 Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography Schaller, Christoph 2018 application/pdf https://epic.awi.de/id/eprint/47495/ https://epic.awi.de/id/eprint/47495/1/CSchaller_Diss_Feb2018_PDFA_final.pdf https://suche.suub.uni-bremen.de/peid=B101792549&CID=6004023 https://hdl.handle.net/10013/epic.ad20190c-e37e-41db-aaaf-4894879643c3 unknown https://epic.awi.de/id/eprint/47495/1/CSchaller_Diss_Feb2018_PDFA_final.pdf Schaller, C. (2018) Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography , PhD thesis, Universität Bremen. hdl:10013/epic.ad20190c-e37e-41db-aaaf-4894879643c3 EPIC373 p. Thesis notRev 2018 ftawi 2024-06-24T04:19:47Z Polar ice cores act as a unique archive of the Earth’s climate system. However, due to logistic constraints, the representativity of these ice-core records cannot be estimated directly. One possible remedy is to analyze the spatial variability in polar snow and firn and combine the results with an improved understanding of the formation of paleoclimatic ice-core signals and their evolution with depth. Here, X-ray computed tomography is applied as a non-destructive method that yields information on stratigraphy and microstructure in polar snow and firn. The results are used to contribute to both subtopics of this indirect approach for estimating representativity. New methods for sampling the snowpack as well as the detection and ali- gnment of coherent signals in spatially-distributed datasets are presented. They are applied to analyze spatial variability in the snowpack both on the local (trench studies in Greenland and East Antarctica, distances up to 100 m) and the regio- nal scale (450 km traverse through North Greenland). The matching algorithm is validated using randomly generated profiles with the same statistical properties as the original data. Snow and firn density as markers of stratigraphy are deter- mined by two-dimensional radioscopic imaging, the water-isotopic δ18O signal is used for age dating. The results show that regionally a significant share of the stratigraphic density signal persists over hundreds of kilometers. Locally, there is a strong directional influence of the wind with a much larger homogeneity of the snowpack along the main wind direction. As density is an important input parameter for remote sen- sing and surface-mass-balance estimates, representative profiles or mean values of snow and firn density are required. Such a profile is provided for the upper two meters of the North Greenland snowpack. On the local scale, the estimation of representative densities for certain areas of interest (such as the footprint of an altimeter) is complicated by the directional dependence of the ... Thesis Antarc* Antarctica East Antarctica Greenland ice core North Greenland Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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Open Polar |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
Polar ice cores act as a unique archive of the Earth’s climate system. However, due to logistic constraints, the representativity of these ice-core records cannot be estimated directly. One possible remedy is to analyze the spatial variability in polar snow and firn and combine the results with an improved understanding of the formation of paleoclimatic ice-core signals and their evolution with depth. Here, X-ray computed tomography is applied as a non-destructive method that yields information on stratigraphy and microstructure in polar snow and firn. The results are used to contribute to both subtopics of this indirect approach for estimating representativity. New methods for sampling the snowpack as well as the detection and ali- gnment of coherent signals in spatially-distributed datasets are presented. They are applied to analyze spatial variability in the snowpack both on the local (trench studies in Greenland and East Antarctica, distances up to 100 m) and the regio- nal scale (450 km traverse through North Greenland). The matching algorithm is validated using randomly generated profiles with the same statistical properties as the original data. Snow and firn density as markers of stratigraphy are deter- mined by two-dimensional radioscopic imaging, the water-isotopic δ18O signal is used for age dating. The results show that regionally a significant share of the stratigraphic density signal persists over hundreds of kilometers. Locally, there is a strong directional influence of the wind with a much larger homogeneity of the snowpack along the main wind direction. As density is an important input parameter for remote sen- sing and surface-mass-balance estimates, representative profiles or mean values of snow and firn density are required. Such a profile is provided for the upper two meters of the North Greenland snowpack. On the local scale, the estimation of representative densities for certain areas of interest (such as the footprint of an altimeter) is complicated by the directional dependence of the ... |
format |
Thesis |
author |
Schaller, Christoph |
spellingShingle |
Schaller, Christoph Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography |
author_facet |
Schaller, Christoph |
author_sort |
Schaller, Christoph |
title |
Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography |
title_short |
Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography |
title_full |
Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography |
title_fullStr |
Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography |
title_full_unstemmed |
Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography |
title_sort |
towards understanding the signal formation in polar snow, firn and ice using x-ray computed tomography |
publishDate |
2018 |
url |
https://epic.awi.de/id/eprint/47495/ https://epic.awi.de/id/eprint/47495/1/CSchaller_Diss_Feb2018_PDFA_final.pdf https://suche.suub.uni-bremen.de/peid=B101792549&CID=6004023 https://hdl.handle.net/10013/epic.ad20190c-e37e-41db-aaaf-4894879643c3 |
genre |
Antarc* Antarctica East Antarctica Greenland ice core North Greenland |
genre_facet |
Antarc* Antarctica East Antarctica Greenland ice core North Greenland |
op_source |
EPIC373 p. |
op_relation |
https://epic.awi.de/id/eprint/47495/1/CSchaller_Diss_Feb2018_PDFA_final.pdf Schaller, C. (2018) Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography , PhD thesis, Universität Bremen. hdl:10013/epic.ad20190c-e37e-41db-aaaf-4894879643c3 |
_version_ |
1810494604524388352 |