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...
Main Author: | |
---|---|
Other Authors: | , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
Universität Bremen
2018
|
Subjects: | |
Online Access: | https://media.suub.uni-bremen.de/handle/elib/1379 https://nbn-resolving.org/urn:nbn:de:gbv:46-00106389-12 |
id |
ftsubbremen:oai:media.suub.uni-bremen.de:Publications/elib/1379 |
---|---|
record_format |
openpolar |
spelling |
ftsubbremen:oai:media.suub.uni-bremen.de:Publications/elib/1379 2023-05-15T13:42:31+02:00 Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography Ein verbessertes Verständnis der Signalbildung in polarem Schnee, Firn und Eis durch Röntgen-Computertomographie Schaller, Christoph Florian Eisen, Olaf Wilhelms, Frank 2018-02-07 application/pdf https://media.suub.uni-bremen.de/handle/elib/1379 https://nbn-resolving.org/urn:nbn:de:gbv:46-00106389-12 eng eng Universität Bremen FB5 Geowissenschaften https://media.suub.uni-bremen.de/handle/elib/1379 urn:nbn:de:gbv:46-00106389-12 info:eu-repo/semantics/openAccess CC BY 4.0 (Attribution) https://creativecommons.org/licenses/by/4.0/ CC-BY Firnification Densification Ice-CT Stratigraphy Microstructure Density Layering AWI 550 550 Earth sciences and geology ddc:550 Dissertation doctoralThesis 2018 ftsubbremen 2023-02-19T23:09:14Z 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 alignment 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 regional 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 determined by two-dimensional radioscopic imaging, the water-isotopic d18O 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 sensing 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 ... Doctoral or Postdoctoral Thesis Antarc* Antarctica East Antarctica Greenland ice core North Greenland Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) East Antarctica Greenland |
institution |
Open Polar |
collection |
Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) |
op_collection_id |
ftsubbremen |
language |
English |
topic |
Firnification Densification Ice-CT Stratigraphy Microstructure Density Layering AWI 550 550 Earth sciences and geology ddc:550 |
spellingShingle |
Firnification Densification Ice-CT Stratigraphy Microstructure Density Layering AWI 550 550 Earth sciences and geology ddc:550 Schaller, Christoph Florian Towards understanding the signal formation in polar snow, firn and ice using X-ray computed tomography |
topic_facet |
Firnification Densification Ice-CT Stratigraphy Microstructure Density Layering AWI 550 550 Earth sciences and geology ddc:550 |
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 alignment 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 regional 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 determined by two-dimensional radioscopic imaging, the water-isotopic d18O 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 sensing 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 ... |
author2 |
Eisen, Olaf Wilhelms, Frank |
format |
Doctoral or Postdoctoral Thesis |
author |
Schaller, Christoph Florian |
author_facet |
Schaller, Christoph Florian |
author_sort |
Schaller, Christoph Florian |
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 |
publisher |
Universität Bremen |
publishDate |
2018 |
url |
https://media.suub.uni-bremen.de/handle/elib/1379 https://nbn-resolving.org/urn:nbn:de:gbv:46-00106389-12 |
geographic |
East Antarctica Greenland |
geographic_facet |
East Antarctica Greenland |
genre |
Antarc* Antarctica East Antarctica Greenland ice core North Greenland |
genre_facet |
Antarc* Antarctica East Antarctica Greenland ice core North Greenland |
op_relation |
https://media.suub.uni-bremen.de/handle/elib/1379 urn:nbn:de:gbv:46-00106389-12 |
op_rights |
info:eu-repo/semantics/openAccess CC BY 4.0 (Attribution) https://creativecommons.org/licenses/by/4.0/ |
op_rightsnorm |
CC-BY |
_version_ |
1766168810814963712 |