Model studies of the coast effect on geomagnetic variations
The effect of a highly conducting ocean on geomagnetic variations has been studied by means of an analog model. Analog model results for a straight coastline show good agreement with analytical results derived for the case of a concentrated current source over the edge of an infinitely conducting oc...
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Canadian Science Publishing
1968
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Online Access: | http://dx.doi.org/10.1139/e68-046 http://www.nrcresearchpress.com/doi/pdf/10.1139/e68-046 |
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crcansciencepubl:10.1139/e68-046 2023-12-17T10:32:05+01:00 Model studies of the coast effect on geomagnetic variations Hermance, John F. 1968 http://dx.doi.org/10.1139/e68-046 http://www.nrcresearchpress.com/doi/pdf/10.1139/e68-046 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 5, issue 3, page 515-522 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1968 crcansciencepubl https://doi.org/10.1139/e68-046 2023-11-19T13:39:35Z The effect of a highly conducting ocean on geomagnetic variations has been studied by means of an analog model. Analog model results for a straight coastline show good agreement with analytical results derived for the case of a concentrated current source over the edge of an infinitely conducting ocean. The analog model was extended to the case of a poorly conducting island of irregular shape in a highly conducting ocean by cutting a hole the desired shape (in this case Iceland) from a large thin sheet of lead. Although anomalous contributions in the H, D, and Z components are observed, the distortion of the horizontal field components is restricted to the seaward side of the coast. Over the interior of the island only the vertical field is affected. The model study was undertaken to provide corrections to measurements made in Iceland for deep conductivity studies. Some field observations were in fact made near the coastline, which show general agreement with the model results, but suggest that the model overemphasized the coast effect through complete neglect of the finite conductivity of the island. The field measurements indicate that at distances of 50 km or more from the coast, for periods longer than a few minutes, the coast effect can be neglected. Article in Journal/Newspaper Iceland Canadian Science Publishing (via Crossref) Canadian Journal of Earth Sciences 5 3 515 522 |
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Open Polar |
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Canadian Science Publishing (via Crossref) |
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crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Hermance, John F. Model studies of the coast effect on geomagnetic variations |
topic_facet |
General Earth and Planetary Sciences |
description |
The effect of a highly conducting ocean on geomagnetic variations has been studied by means of an analog model. Analog model results for a straight coastline show good agreement with analytical results derived for the case of a concentrated current source over the edge of an infinitely conducting ocean. The analog model was extended to the case of a poorly conducting island of irregular shape in a highly conducting ocean by cutting a hole the desired shape (in this case Iceland) from a large thin sheet of lead. Although anomalous contributions in the H, D, and Z components are observed, the distortion of the horizontal field components is restricted to the seaward side of the coast. Over the interior of the island only the vertical field is affected. The model study was undertaken to provide corrections to measurements made in Iceland for deep conductivity studies. Some field observations were in fact made near the coastline, which show general agreement with the model results, but suggest that the model overemphasized the coast effect through complete neglect of the finite conductivity of the island. The field measurements indicate that at distances of 50 km or more from the coast, for periods longer than a few minutes, the coast effect can be neglected. |
format |
Article in Journal/Newspaper |
author |
Hermance, John F. |
author_facet |
Hermance, John F. |
author_sort |
Hermance, John F. |
title |
Model studies of the coast effect on geomagnetic variations |
title_short |
Model studies of the coast effect on geomagnetic variations |
title_full |
Model studies of the coast effect on geomagnetic variations |
title_fullStr |
Model studies of the coast effect on geomagnetic variations |
title_full_unstemmed |
Model studies of the coast effect on geomagnetic variations |
title_sort |
model studies of the coast effect on geomagnetic variations |
publisher |
Canadian Science Publishing |
publishDate |
1968 |
url |
http://dx.doi.org/10.1139/e68-046 http://www.nrcresearchpress.com/doi/pdf/10.1139/e68-046 |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
Canadian Journal of Earth Sciences volume 5, issue 3, page 515-522 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e68-046 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
5 |
container_issue |
3 |
container_start_page |
515 |
op_container_end_page |
522 |
_version_ |
1785585586299469824 |