Depth of origin of ocean-circulation-induced magnetic signals
As the world ocean moves through the ambient geomagnetic core field, electric currents are generated in the entire ocean basin. These oceanic electric currents induce weak magnetic signals that are principally observable outside of the ocean and allow inferences about large-scale oceanic transports...
Published in: | Annales Geophysicae |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2018
|
Subjects: | |
Online Access: | https://doi.org/10.5194/angeo-36-167-2018 https://doaj.org/article/b2d0320655054097bfe6cb4a3b7e3422 |
id |
ftdoajarticles:oai:doaj.org/article:b2d0320655054097bfe6cb4a3b7e3422 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:b2d0320655054097bfe6cb4a3b7e3422 2023-05-15T13:56:37+02:00 Depth of origin of ocean-circulation-induced magnetic signals C. Irrgang J. Saynisch-Wagner M. Thomas 2018-01-01T00:00:00Z https://doi.org/10.5194/angeo-36-167-2018 https://doaj.org/article/b2d0320655054097bfe6cb4a3b7e3422 EN eng Copernicus Publications https://www.ann-geophys.net/36/167/2018/angeo-36-167-2018.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-36-167-2018 0992-7689 1432-0576 https://doaj.org/article/b2d0320655054097bfe6cb4a3b7e3422 Annales Geophysicae, Vol 36, Pp 167-180 (2018) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2018 ftdoajarticles https://doi.org/10.5194/angeo-36-167-2018 2022-12-30T23:30:55Z As the world ocean moves through the ambient geomagnetic core field, electric currents are generated in the entire ocean basin. These oceanic electric currents induce weak magnetic signals that are principally observable outside of the ocean and allow inferences about large-scale oceanic transports of water, heat, and salinity. The ocean-induced magnetic field is an integral quantity and, to first order, it is proportional to depth-integrated and conductivity-weighted ocean currents. However, the specific contribution of oceanic transports at different depths to the motional induction process remains unclear and is examined in this study. We show that large-scale motional induction due to the general ocean circulation is dominantly generated by ocean currents in the upper 2000 m of the ocean basin. In particular, our findings allow relating regional patterns of the oceanic magnetic field to corresponding oceanic transports at different depths. Ocean currents below 3000 m, in contrast, only contribute a small fraction to the ocean-induced magnetic signal strength with values up to 0.2 nT at sea surface and less than 0.1 nT at the Swarm satellite altitude. Thereby, potential satellite observations of ocean-circulation-induced magnetic signals are found to be likely insensitive to deep ocean currents. Furthermore, it is shown that annual temporal variations of the ocean-induced magnetic field in the region of the Antarctic Circumpolar Current contain information about sub-surface ocean currents below 1000 m with intra-annual periods. Specifically, ocean currents with sub-monthly periods dominate the annual temporal variability of the ocean-induced magnetic field. Article in Journal/Newspaper Antarc* Antarctic Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic Annales Geophysicae 36 1 167 180 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 C. Irrgang J. Saynisch-Wagner M. Thomas Depth of origin of ocean-circulation-induced magnetic signals |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
As the world ocean moves through the ambient geomagnetic core field, electric currents are generated in the entire ocean basin. These oceanic electric currents induce weak magnetic signals that are principally observable outside of the ocean and allow inferences about large-scale oceanic transports of water, heat, and salinity. The ocean-induced magnetic field is an integral quantity and, to first order, it is proportional to depth-integrated and conductivity-weighted ocean currents. However, the specific contribution of oceanic transports at different depths to the motional induction process remains unclear and is examined in this study. We show that large-scale motional induction due to the general ocean circulation is dominantly generated by ocean currents in the upper 2000 m of the ocean basin. In particular, our findings allow relating regional patterns of the oceanic magnetic field to corresponding oceanic transports at different depths. Ocean currents below 3000 m, in contrast, only contribute a small fraction to the ocean-induced magnetic signal strength with values up to 0.2 nT at sea surface and less than 0.1 nT at the Swarm satellite altitude. Thereby, potential satellite observations of ocean-circulation-induced magnetic signals are found to be likely insensitive to deep ocean currents. Furthermore, it is shown that annual temporal variations of the ocean-induced magnetic field in the region of the Antarctic Circumpolar Current contain information about sub-surface ocean currents below 1000 m with intra-annual periods. Specifically, ocean currents with sub-monthly periods dominate the annual temporal variability of the ocean-induced magnetic field. |
format |
Article in Journal/Newspaper |
author |
C. Irrgang J. Saynisch-Wagner M. Thomas |
author_facet |
C. Irrgang J. Saynisch-Wagner M. Thomas |
author_sort |
C. Irrgang |
title |
Depth of origin of ocean-circulation-induced magnetic signals |
title_short |
Depth of origin of ocean-circulation-induced magnetic signals |
title_full |
Depth of origin of ocean-circulation-induced magnetic signals |
title_fullStr |
Depth of origin of ocean-circulation-induced magnetic signals |
title_full_unstemmed |
Depth of origin of ocean-circulation-induced magnetic signals |
title_sort |
depth of origin of ocean-circulation-induced magnetic signals |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-36-167-2018 https://doaj.org/article/b2d0320655054097bfe6cb4a3b7e3422 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Annales Geophysicae, Vol 36, Pp 167-180 (2018) |
op_relation |
https://www.ann-geophys.net/36/167/2018/angeo-36-167-2018.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-36-167-2018 0992-7689 1432-0576 https://doaj.org/article/b2d0320655054097bfe6cb4a3b7e3422 |
op_doi |
https://doi.org/10.5194/angeo-36-167-2018 |
container_title |
Annales Geophysicae |
container_volume |
36 |
container_issue |
1 |
container_start_page |
167 |
op_container_end_page |
180 |
_version_ |
1766264161434599424 |