Magnetotelluric Fields of a Gaussian Electrojet
In a previous paper (Hermance and Peltier 1970), integral expressions for the magnetotelluric fields of a line source over a stratified conductor were obtained and numerically evaluated for a sequence of simple conductivity structures. This calculation was intended to simulate the magnetotelluric ...
Published in: | Canadian Journal of Earth Sciences |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
1971
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1139/e71-034 http://www.nrcresearchpress.com/doi/pdf/10.1139/e71-034 |
id |
crcansciencepubl:10.1139/e71-034 |
---|---|
record_format |
openpolar |
spelling |
crcansciencepubl:10.1139/e71-034 2024-05-19T07:42:51+00:00 Magnetotelluric Fields of a Gaussian Electrojet Peltier, W. R. Hermance, J. F. 1971 http://dx.doi.org/10.1139/e71-034 http://www.nrcresearchpress.com/doi/pdf/10.1139/e71-034 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 8, issue 3, page 338-346 ISSN 0008-4077 1480-3313 journal-article 1971 crcansciencepubl https://doi.org/10.1139/e71-034 2024-05-02T06:51:25Z In a previous paper (Hermance and Peltier 1970), integral expressions for the magnetotelluric fields of a line source over a stratified conductor were obtained and numerically evaluated for a sequence of simple conductivity structures. This calculation was intended to simulate the magnetotelluric 'source effect' which is anticipated at auroral and equatorial latitudes. The most serious flaw in this line source model of an electrojet is that it does not take into account the laterally diffuse nature of the real current distribution. By assuming that the current density in the electrojet has a Gaussian dependence upon the horizontal coordinate a more realistic source model can be constructed. Representative solutions to the induction problem employing this source are analyzed in an effort to obtain a more accurate measure of the effect of finite source geometry on magnetotelluric interpretations in auroral and equatorial regions where strong electrojets exist at E-layer altitudes. In tectonically active areas such as Iceland (which is under the auroral electrojet), it appears that Cagniard's assumption of a "plane-wave" source leads to a correct interpretation of the subsurface conductivity structure in the commonly employed U.L.F. frequency band (10 −4 Hz–1 Hz). A relationship, Tozer (1969), is here assumed to exist between tectonism, anomalously high near surface temperatures, and corresponding increases in electrical conductivity. In tectonically stable shield areas, however, the effect of finite source geometry is more pronounced and could lead to significant errors in interpretation. Article in Journal/Newspaper Iceland Canadian Science Publishing Canadian Journal of Earth Sciences 8 3 338 346 |
institution |
Open Polar |
collection |
Canadian Science Publishing |
op_collection_id |
crcansciencepubl |
language |
English |
description |
In a previous paper (Hermance and Peltier 1970), integral expressions for the magnetotelluric fields of a line source over a stratified conductor were obtained and numerically evaluated for a sequence of simple conductivity structures. This calculation was intended to simulate the magnetotelluric 'source effect' which is anticipated at auroral and equatorial latitudes. The most serious flaw in this line source model of an electrojet is that it does not take into account the laterally diffuse nature of the real current distribution. By assuming that the current density in the electrojet has a Gaussian dependence upon the horizontal coordinate a more realistic source model can be constructed. Representative solutions to the induction problem employing this source are analyzed in an effort to obtain a more accurate measure of the effect of finite source geometry on magnetotelluric interpretations in auroral and equatorial regions where strong electrojets exist at E-layer altitudes. In tectonically active areas such as Iceland (which is under the auroral electrojet), it appears that Cagniard's assumption of a "plane-wave" source leads to a correct interpretation of the subsurface conductivity structure in the commonly employed U.L.F. frequency band (10 −4 Hz–1 Hz). A relationship, Tozer (1969), is here assumed to exist between tectonism, anomalously high near surface temperatures, and corresponding increases in electrical conductivity. In tectonically stable shield areas, however, the effect of finite source geometry is more pronounced and could lead to significant errors in interpretation. |
format |
Article in Journal/Newspaper |
author |
Peltier, W. R. Hermance, J. F. |
spellingShingle |
Peltier, W. R. Hermance, J. F. Magnetotelluric Fields of a Gaussian Electrojet |
author_facet |
Peltier, W. R. Hermance, J. F. |
author_sort |
Peltier, W. R. |
title |
Magnetotelluric Fields of a Gaussian Electrojet |
title_short |
Magnetotelluric Fields of a Gaussian Electrojet |
title_full |
Magnetotelluric Fields of a Gaussian Electrojet |
title_fullStr |
Magnetotelluric Fields of a Gaussian Electrojet |
title_full_unstemmed |
Magnetotelluric Fields of a Gaussian Electrojet |
title_sort |
magnetotelluric fields of a gaussian electrojet |
publisher |
Canadian Science Publishing |
publishDate |
1971 |
url |
http://dx.doi.org/10.1139/e71-034 http://www.nrcresearchpress.com/doi/pdf/10.1139/e71-034 |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
Canadian Journal of Earth Sciences volume 8, issue 3, page 338-346 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e71-034 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
8 |
container_issue |
3 |
container_start_page |
338 |
op_container_end_page |
346 |
_version_ |
1799482558086381568 |