Earth's magnetic field over the last 1000 years
To investigate the reliability and stability of spherical harmonic models based on archeo/-paleomagnetic data, 2000 Geomagnetic models were calculated. All models are based on the same data set but with randomized uncertainties. Comparison of these models to the geomagnetic field model gufm1 showed...
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ftubpotsdam:oai:kobv.de-opus4-uni-potsdam:47315 2023-07-02T03:32:27+02:00 Earth's magnetic field over the last 1000 years Senftleben, Robin 2020 application/pdf https://publishup.uni-potsdam.de/frontdoor/index/index/docId/47315 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus4-473150 https://doi.org/10.25932/publishup-47315 https://publishup.uni-potsdam.de/files/47315/senftleben_diss.pdf eng eng https://publishup.uni-potsdam.de/frontdoor/index/index/docId/47315 urn:nbn:de:kobv:517-opus4-473150 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus4-473150 https://doi.org/10.25932/publishup-47315 https://publishup.uni-potsdam.de/files/47315/senftleben_diss.pdf https://rightsstatements.org/vocab/InC/1.0/ info:eu-repo/semantics/openAccess ddc:500 Institut für Geowissenschaften doctoralthesis doc-type:doctoralThesis 2020 ftubpotsdam https://doi.org/10.25932/publishup-47315 2023-06-11T22:36:49Z To investigate the reliability and stability of spherical harmonic models based on archeo/-paleomagnetic data, 2000 Geomagnetic models were calculated. All models are based on the same data set but with randomized uncertainties. Comparison of these models to the geomagnetic field model gufm1 showed that large scale magnetic field structures up to spherical harmonic degree 4 are stable throughout all models. Through a ranking of all models by comparing the dipole coefficients to gufm1 more realistic uncertainty estimates were derived than the authors of the data provide. The derived uncertainty estimates were used in further modelling, which combines archeo/-paleomagnetic and historical data. The huge difference in data count, accuracy and coverage of these two very different data sources made it necessary to introduce a time dependent spatial damping, which was constructed to constrain the spatial complexity of the model. Finally 501 models were calculated by considering that each data point is a Gaussian random variable, whose mean is the original value and whose standard deviation is its uncertainty. The final model arhimag1k is calculated by taking the mean of the 501 sets of Gauss coefficients. arhimag1k fits different dependent and independent data sets well. It shows an early reverse flux patch at the core-mantle boundary between 1000 AD and 1200 AD at the location of the South Atlantic Anomaly today. Another interesting feature is a high latitude flux patch over Greenland between 1200 and 1400 AD. The dipole moment shows a constant behaviour between 1600 and 1840 AD. In the second part of the thesis 4 new paleointensities from 4 different flows of the island Fogo, which is part of Cape Verde, are presented. The data is fitted well by arhimag1k with the exception of the value at 1663 of 28.3 microtesla, which is approximately 10 microtesla lower than the model suggest. Um die Stabilität und Zuverlässigkeit von sphärisch harmonischen Erdmagnetfeldmodellen, die auf paleomagnetischen und archeomagnetischen ... Doctoral or Postdoctoral Thesis Greenland University of Potsdam: publish.UP Greenland Fogo ENVELOPE(-54.281,-54.281,49.717,49.717) |
institution |
Open Polar |
collection |
University of Potsdam: publish.UP |
op_collection_id |
ftubpotsdam |
language |
English |
topic |
ddc:500 Institut für Geowissenschaften |
spellingShingle |
ddc:500 Institut für Geowissenschaften Senftleben, Robin Earth's magnetic field over the last 1000 years |
topic_facet |
ddc:500 Institut für Geowissenschaften |
description |
To investigate the reliability and stability of spherical harmonic models based on archeo/-paleomagnetic data, 2000 Geomagnetic models were calculated. All models are based on the same data set but with randomized uncertainties. Comparison of these models to the geomagnetic field model gufm1 showed that large scale magnetic field structures up to spherical harmonic degree 4 are stable throughout all models. Through a ranking of all models by comparing the dipole coefficients to gufm1 more realistic uncertainty estimates were derived than the authors of the data provide. The derived uncertainty estimates were used in further modelling, which combines archeo/-paleomagnetic and historical data. The huge difference in data count, accuracy and coverage of these two very different data sources made it necessary to introduce a time dependent spatial damping, which was constructed to constrain the spatial complexity of the model. Finally 501 models were calculated by considering that each data point is a Gaussian random variable, whose mean is the original value and whose standard deviation is its uncertainty. The final model arhimag1k is calculated by taking the mean of the 501 sets of Gauss coefficients. arhimag1k fits different dependent and independent data sets well. It shows an early reverse flux patch at the core-mantle boundary between 1000 AD and 1200 AD at the location of the South Atlantic Anomaly today. Another interesting feature is a high latitude flux patch over Greenland between 1200 and 1400 AD. The dipole moment shows a constant behaviour between 1600 and 1840 AD. In the second part of the thesis 4 new paleointensities from 4 different flows of the island Fogo, which is part of Cape Verde, are presented. The data is fitted well by arhimag1k with the exception of the value at 1663 of 28.3 microtesla, which is approximately 10 microtesla lower than the model suggest. Um die Stabilität und Zuverlässigkeit von sphärisch harmonischen Erdmagnetfeldmodellen, die auf paleomagnetischen und archeomagnetischen ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Senftleben, Robin |
author_facet |
Senftleben, Robin |
author_sort |
Senftleben, Robin |
title |
Earth's magnetic field over the last 1000 years |
title_short |
Earth's magnetic field over the last 1000 years |
title_full |
Earth's magnetic field over the last 1000 years |
title_fullStr |
Earth's magnetic field over the last 1000 years |
title_full_unstemmed |
Earth's magnetic field over the last 1000 years |
title_sort |
earth's magnetic field over the last 1000 years |
publishDate |
2020 |
url |
https://publishup.uni-potsdam.de/frontdoor/index/index/docId/47315 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus4-473150 https://doi.org/10.25932/publishup-47315 https://publishup.uni-potsdam.de/files/47315/senftleben_diss.pdf |
long_lat |
ENVELOPE(-54.281,-54.281,49.717,49.717) |
geographic |
Greenland Fogo |
geographic_facet |
Greenland Fogo |
genre |
Greenland |
genre_facet |
Greenland |
op_relation |
https://publishup.uni-potsdam.de/frontdoor/index/index/docId/47315 urn:nbn:de:kobv:517-opus4-473150 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus4-473150 https://doi.org/10.25932/publishup-47315 https://publishup.uni-potsdam.de/files/47315/senftleben_diss.pdf |
op_rights |
https://rightsstatements.org/vocab/InC/1.0/ info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.25932/publishup-47315 |
_version_ |
1770272036044668928 |