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Digitizing UK analogue magnetogram records from large geomagnetic storms of the past two centuries

Continuous geomagnetic records of the strength and direction of the Earth's field at the surface extend back to the 1840s. Over the past two centuries, eight observatories have existed in the United Kingdom, which measured the daily field variations using light‐sensitive photographic paper to p...

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Autores principales: Beggan, Ciaran D., Eaton, Eliot, Maume, Eleanor, Clarke, Ellen, Williamson, John, Humphries, Thomas
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10078682/
https://www.ncbi.nlm.nih.gov/pubmed/37035263
http://dx.doi.org/10.1002/gdj3.151
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author Beggan, Ciaran D.
Eaton, Eliot
Maume, Eleanor
Clarke, Ellen
Williamson, John
Humphries, Thomas
author_facet Beggan, Ciaran D.
Eaton, Eliot
Maume, Eleanor
Clarke, Ellen
Williamson, John
Humphries, Thomas
author_sort Beggan, Ciaran D.
collection PubMed
description Continuous geomagnetic records of the strength and direction of the Earth's field at the surface extend back to the 1840s. Over the past two centuries, eight observatories have existed in the United Kingdom, which measured the daily field variations using light‐sensitive photographic paper to produce analogue magnetograms. Around 350,000 magnetograms have been digitally photographed at high resolution. However, converting the traces to digital values is difficult and time consuming as the magnetograms can have over‐lapping lines, low quality recordings and obscure metadata for conversion to SI units. We discuss our approach to digitizing the traces from large geomagnetic storms and highlight some of the issues to be aware of when capturing magnetic information from analogue measurements. These include cross‐checking the final digitized values with the recorded hourly mean values from observatory year books and comparing several observatory records for the same storm to catch errors such as sign inversions or incorrect ‘wrap‐around’ of data on the paper records.
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spelling pubmed-100786822023-04-07 Digitizing UK analogue magnetogram records from large geomagnetic storms of the past two centuries Beggan, Ciaran D. Eaton, Eliot Maume, Eleanor Clarke, Ellen Williamson, John Humphries, Thomas Geosci Data J Data Services Articles Continuous geomagnetic records of the strength and direction of the Earth's field at the surface extend back to the 1840s. Over the past two centuries, eight observatories have existed in the United Kingdom, which measured the daily field variations using light‐sensitive photographic paper to produce analogue magnetograms. Around 350,000 magnetograms have been digitally photographed at high resolution. However, converting the traces to digital values is difficult and time consuming as the magnetograms can have over‐lapping lines, low quality recordings and obscure metadata for conversion to SI units. We discuss our approach to digitizing the traces from large geomagnetic storms and highlight some of the issues to be aware of when capturing magnetic information from analogue measurements. These include cross‐checking the final digitized values with the recorded hourly mean values from observatory year books and comparing several observatory records for the same storm to catch errors such as sign inversions or incorrect ‘wrap‐around’ of data on the paper records. John Wiley and Sons Inc. 2022-03-28 2023-01 /pmc/articles/PMC10078682/ /pubmed/37035263 http://dx.doi.org/10.1002/gdj3.151 Text en © 2022 British Geological Survey. Geoscience Data Journal published by Royal Meteorological Society and John Wiley & Sons Ltd. https://creativecommons.org/licenses/by/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Data Services Articles
Beggan, Ciaran D.
Eaton, Eliot
Maume, Eleanor
Clarke, Ellen
Williamson, John
Humphries, Thomas
Digitizing UK analogue magnetogram records from large geomagnetic storms of the past two centuries
title Digitizing UK analogue magnetogram records from large geomagnetic storms of the past two centuries
title_full Digitizing UK analogue magnetogram records from large geomagnetic storms of the past two centuries
title_fullStr Digitizing UK analogue magnetogram records from large geomagnetic storms of the past two centuries
title_full_unstemmed Digitizing UK analogue magnetogram records from large geomagnetic storms of the past two centuries
title_short Digitizing UK analogue magnetogram records from large geomagnetic storms of the past two centuries
title_sort digitizing uk analogue magnetogram records from large geomagnetic storms of the past two centuries
topic Data Services Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10078682/
https://www.ncbi.nlm.nih.gov/pubmed/37035263
http://dx.doi.org/10.1002/gdj3.151
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