Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset
Storm sudden commencements (SSC) often precede geomagnetic storms. Commonly, it takes some hours from the step-like change that marks the SSC to the start of the magnetic storm activity. In a subset of cases, however, auroral activity starts almost instantaneously after the SSC. To the authors knowl...
Published in: | Journal of Geophysical Research: Space Physics |
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ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_5011090 2023-05-15T16:12:07+02:00 Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset Zhou, Y. Lühr, H. 2022 application/pdf https://gfzpublic.gfz-potsdam.de/pubman/item/item_5011090 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5011090_1/component/file_5011120/5011090.pdf eng eng info:eu-repo/semantics/altIdentifier/doi/10.1029/2021JA030050 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5011090 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5011090_1/component/file_5011120/5011090.pdf info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by/4.0/ CC-BY Journal of Geophysical Research: Space Physics info:eu-repo/semantics/article 2022 ftgfzpotsdam https://doi.org/10.1029/2021JA030050 2023-02-06T00:33:48Z Storm sudden commencements (SSC) often precede geomagnetic storms. Commonly, it takes some hours from the step-like change that marks the SSC to the start of the magnetic storm activity. In a subset of cases, however, auroral activity starts almost instantaneously after the SSC. To the authors knowledge, the conditions that enable this rapid activation have not been investigated in detail before. Here we consider all the sudden commencements (SC) during the years 2000–2020. Our focus is on the initial response of the auroral currents on the nightside. For that purpose, we make use of the IMAGE Magnetometer Network in Fennoscandia. In about 30% of SC events an initial activation of the westward electrojet is observed. Magnetic deflections of the northward component, surpassing frequently 1,000 nT, are observed only 4 min after the SC. These intense westward currents, flowing typically in narrow channels of 1°–2° latitudinal width, last some 10 min. The electrojets are conjugate to regions in the magnetosphere near geostationary orbits. In several cases geomagnetic substorm onsets are observed about 30 min after the SC. These start typically at fairly high latitude, around 71° magnetic latitude. This is an indication for rather quiet conditions preceding the onset. The magnetic pulse of the SC seems to play an important role in initiating the strong electrojets and the substorms. These initial activities are of relevance for space weather effects because of their strong and rapid variations. This paper provides detailed observations of the initial auroral activity following some SCs. Article in Journal/Newspaper Fennoscandia GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) Journal of Geophysical Research: Space Physics 127 4 |
institution |
Open Polar |
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GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
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ftgfzpotsdam |
language |
English |
description |
Storm sudden commencements (SSC) often precede geomagnetic storms. Commonly, it takes some hours from the step-like change that marks the SSC to the start of the magnetic storm activity. In a subset of cases, however, auroral activity starts almost instantaneously after the SSC. To the authors knowledge, the conditions that enable this rapid activation have not been investigated in detail before. Here we consider all the sudden commencements (SC) during the years 2000–2020. Our focus is on the initial response of the auroral currents on the nightside. For that purpose, we make use of the IMAGE Magnetometer Network in Fennoscandia. In about 30% of SC events an initial activation of the westward electrojet is observed. Magnetic deflections of the northward component, surpassing frequently 1,000 nT, are observed only 4 min after the SC. These intense westward currents, flowing typically in narrow channels of 1°–2° latitudinal width, last some 10 min. The electrojets are conjugate to regions in the magnetosphere near geostationary orbits. In several cases geomagnetic substorm onsets are observed about 30 min after the SC. These start typically at fairly high latitude, around 71° magnetic latitude. This is an indication for rather quiet conditions preceding the onset. The magnetic pulse of the SC seems to play an important role in initiating the strong electrojets and the substorms. These initial activities are of relevance for space weather effects because of their strong and rapid variations. This paper provides detailed observations of the initial auroral activity following some SCs. |
format |
Article in Journal/Newspaper |
author |
Zhou, Y. Lühr, H. |
spellingShingle |
Zhou, Y. Lühr, H. Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset |
author_facet |
Zhou, Y. Lühr, H. |
author_sort |
Zhou, Y. |
title |
Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset |
title_short |
Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset |
title_full |
Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset |
title_fullStr |
Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset |
title_full_unstemmed |
Initial Response of Nightside Auroral Currents to a Sudden Commencement: Observations of Electrojet and Substorm Onset |
title_sort |
initial response of nightside auroral currents to a sudden commencement: observations of electrojet and substorm onset |
publishDate |
2022 |
url |
https://gfzpublic.gfz-potsdam.de/pubman/item/item_5011090 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5011090_1/component/file_5011120/5011090.pdf |
genre |
Fennoscandia |
genre_facet |
Fennoscandia |
op_source |
Journal of Geophysical Research: Space Physics |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2021JA030050 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5011090 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5011090_1/component/file_5011120/5011090.pdf |
op_rights |
info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by/4.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1029/2021JA030050 |
container_title |
Journal of Geophysical Research: Space Physics |
container_volume |
127 |
container_issue |
4 |
_version_ |
1765997357126647808 |