Seeking a seafloor magnetic signal from the Antarctic circumpolar current
Motional electromagnetic induction by ocean currents is a basic phenomenon of geophysics, with application to the monitoring of ocean transport. One of Earth's strongest ocean currents is the Antarctic circumpolar current (ACC). This paper explores the magnetic signals that should be generated...
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/85496 2024-01-14T10:00:05+01:00 Seeking a seafloor magnetic signal from the Antarctic circumpolar current Lilley, F. E. M. White, A. Heinson, Graham Procko, K. http://hdl.handle.net/1885/85496 https://doi.org/10.1111/j.1365-246X.2004.02174.x unknown Blackwell Publishing Ltd 0956-540X http://hdl.handle.net/1885/85496 doi:10.1111/j.1365-246X.2004.02174.x Geophysical Journal International Keywords: geomagnetism magnetometer measurement method oceanic current seafloor Southern Ocean Antarctic Circumpolar current Geomagnetism Motional induction Seafloor magnetometers Southern ocean Journal article ftanucanberra https://doi.org/10.1111/j.1365-246X.2004.02174.x 2023-12-15T09:36:43Z Motional electromagnetic induction by ocean currents is a basic phenomenon of geophysics, with application to the monitoring of ocean transport. One of Earth's strongest ocean currents is the Antarctic circumpolar current (ACC). This paper explores the magnetic signals that should be generated by the ACC, and reports an experiment in which a magnetometer recorded natural variations of Earth's magnetic field on the floor of the Southern ocean for some five months in 1996. Magnetometer records from Kingston, Tasmania, and from Macquarie Island give reference information concerning magnetic storms and substorms. The instrument was sited in the region of the major oceanographic subantarctic flux and dynamics experiment (SAFDE), where the ACC passes south of Tasmania, between the major topographic features of the South Tasman rise and the Australia-Antarctica spreading ridge. The SAFDE records give comprehensive control on the actual ocean current flow at the time of the magnetic recording, and allow a magnetic signal to be predicted, in terms of the seafloor conductance. The seafloor conductance for the area is however low, and the amplitude of the predicted signal is low. The seafloor observations confirm that the signal is weak against the effects of ionospheric signals. In future experiments, the choice of sites with thicker seafloor sedimentation would increase the ACC magnetic signal to be observed. The magnetometer measurements have a result relevant for the SAFDE, in confirming that the correction of electric data for seafloor conductance is small. There is also the result for seafloor magnetic observatories for which motional induction effects are unwanted, that such an observatory can operate even under the ACC, and be substantially protected from motional induction effects by low seafloor conductance. Article in Journal/Newspaper Antarc* Antarctic Antarctica Macquarie Island Southern Ocean Australian National University: ANU Digital Collections Antarctic Southern Ocean The Antarctic South Tasman Rise ENVELOPE(148.000,148.000,-47.500,-47.500) Geophysical Journal International 157 1 175 186 |
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Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: geomagnetism magnetometer measurement method oceanic current seafloor Southern Ocean Antarctic Circumpolar current Geomagnetism Motional induction Seafloor magnetometers Southern ocean |
spellingShingle |
Keywords: geomagnetism magnetometer measurement method oceanic current seafloor Southern Ocean Antarctic Circumpolar current Geomagnetism Motional induction Seafloor magnetometers Southern ocean Lilley, F. E. M. White, A. Heinson, Graham Procko, K. Seeking a seafloor magnetic signal from the Antarctic circumpolar current |
topic_facet |
Keywords: geomagnetism magnetometer measurement method oceanic current seafloor Southern Ocean Antarctic Circumpolar current Geomagnetism Motional induction Seafloor magnetometers Southern ocean |
description |
Motional electromagnetic induction by ocean currents is a basic phenomenon of geophysics, with application to the monitoring of ocean transport. One of Earth's strongest ocean currents is the Antarctic circumpolar current (ACC). This paper explores the magnetic signals that should be generated by the ACC, and reports an experiment in which a magnetometer recorded natural variations of Earth's magnetic field on the floor of the Southern ocean for some five months in 1996. Magnetometer records from Kingston, Tasmania, and from Macquarie Island give reference information concerning magnetic storms and substorms. The instrument was sited in the region of the major oceanographic subantarctic flux and dynamics experiment (SAFDE), where the ACC passes south of Tasmania, between the major topographic features of the South Tasman rise and the Australia-Antarctica spreading ridge. The SAFDE records give comprehensive control on the actual ocean current flow at the time of the magnetic recording, and allow a magnetic signal to be predicted, in terms of the seafloor conductance. The seafloor conductance for the area is however low, and the amplitude of the predicted signal is low. The seafloor observations confirm that the signal is weak against the effects of ionospheric signals. In future experiments, the choice of sites with thicker seafloor sedimentation would increase the ACC magnetic signal to be observed. The magnetometer measurements have a result relevant for the SAFDE, in confirming that the correction of electric data for seafloor conductance is small. There is also the result for seafloor magnetic observatories for which motional induction effects are unwanted, that such an observatory can operate even under the ACC, and be substantially protected from motional induction effects by low seafloor conductance. |
format |
Article in Journal/Newspaper |
author |
Lilley, F. E. M. White, A. Heinson, Graham Procko, K. |
author_facet |
Lilley, F. E. M. White, A. Heinson, Graham Procko, K. |
author_sort |
Lilley, F. E. M. |
title |
Seeking a seafloor magnetic signal from the Antarctic circumpolar current |
title_short |
Seeking a seafloor magnetic signal from the Antarctic circumpolar current |
title_full |
Seeking a seafloor magnetic signal from the Antarctic circumpolar current |
title_fullStr |
Seeking a seafloor magnetic signal from the Antarctic circumpolar current |
title_full_unstemmed |
Seeking a seafloor magnetic signal from the Antarctic circumpolar current |
title_sort |
seeking a seafloor magnetic signal from the antarctic circumpolar current |
publisher |
Blackwell Publishing Ltd |
url |
http://hdl.handle.net/1885/85496 https://doi.org/10.1111/j.1365-246X.2004.02174.x |
long_lat |
ENVELOPE(148.000,148.000,-47.500,-47.500) |
geographic |
Antarctic Southern Ocean The Antarctic South Tasman Rise |
geographic_facet |
Antarctic Southern Ocean The Antarctic South Tasman Rise |
genre |
Antarc* Antarctic Antarctica Macquarie Island Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctica Macquarie Island Southern Ocean |
op_source |
Geophysical Journal International |
op_relation |
0956-540X http://hdl.handle.net/1885/85496 doi:10.1111/j.1365-246X.2004.02174.x |
op_doi |
https://doi.org/10.1111/j.1365-246X.2004.02174.x |
container_title |
Geophysical Journal International |
container_volume |
157 |
container_issue |
1 |
container_start_page |
175 |
op_container_end_page |
186 |
_version_ |
1788063476067860480 |