Observations of an auroral streamer in a double oval configuration
During the late evening and night of 14 September 2004, the nightside auroral oval shows a distinct double oval configuration for several hours after a substorm onset at ~18:45 UT. This structure is observed both by the IMAGE satellite optical instruments focusing on the Southern Hemisphere, and by...
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ftcopernicus:oai:publications.copernicus.org:angeo10495 2023-05-15T16:04:46+02:00 Observations of an auroral streamer in a double oval configuration Amm, O. Nakamura, R. Takada, T. Kauristie, K. Frey, H. U. Owen, C. J. Aikio, A. Kuula, R. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-29-701-2011 https://angeo.copernicus.org/articles/29/701/2011/ eng eng doi:10.5194/angeo-29-701-2011 https://angeo.copernicus.org/articles/29/701/2011/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-29-701-2011 2020-07-20T16:26:09Z During the late evening and night of 14 September 2004, the nightside auroral oval shows a distinct double oval configuration for several hours after a substorm onset at ~18:45 UT. This structure is observed both by the IMAGE satellite optical instruments focusing on the Southern Hemisphere, and by the MIRACLE ground-based instrument network in Scandinavia. At ~21:17 UT during the recovery phase of the substorm, an auroral streamer is detected by these instruments and the EISCAT radar, while simultaneously the Cluster satellites observe a bursty bulk flow in the conjugate portion of the plasma sheet in the magnetotail. Our combined data analysis reveals significant differences between the ionospheric equivalent current signature of this streamer within a double oval configuration, as compared to previously studied streamer events without such a configuration. We attribute these differences to the presence of an additional poleward polarization electric field between the poleward and the equatorward portions of the double oval, and show with a simple model that such an assumption can conceptually explain the observations. Further, we estimate the total current transferred in meridional direction by this recovery phase streamer to ~80 kA, significantly less than for previously analysed expansion phase streamer events. Both results indicate that the development of auroral streamers is dependent on the ambient background conditions in the magnetosphere-ionosphere system. The auroral streamer event studied was simultaneously observed in the conjugate Northern and Southern Hemisphere ionosphere. Text EISCAT Copernicus Publications: E-Journals Annales Geophysicae 29 4 701 716 |
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Open Polar |
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Copernicus Publications: E-Journals |
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English |
description |
During the late evening and night of 14 September 2004, the nightside auroral oval shows a distinct double oval configuration for several hours after a substorm onset at ~18:45 UT. This structure is observed both by the IMAGE satellite optical instruments focusing on the Southern Hemisphere, and by the MIRACLE ground-based instrument network in Scandinavia. At ~21:17 UT during the recovery phase of the substorm, an auroral streamer is detected by these instruments and the EISCAT radar, while simultaneously the Cluster satellites observe a bursty bulk flow in the conjugate portion of the plasma sheet in the magnetotail. Our combined data analysis reveals significant differences between the ionospheric equivalent current signature of this streamer within a double oval configuration, as compared to previously studied streamer events without such a configuration. We attribute these differences to the presence of an additional poleward polarization electric field between the poleward and the equatorward portions of the double oval, and show with a simple model that such an assumption can conceptually explain the observations. Further, we estimate the total current transferred in meridional direction by this recovery phase streamer to ~80 kA, significantly less than for previously analysed expansion phase streamer events. Both results indicate that the development of auroral streamers is dependent on the ambient background conditions in the magnetosphere-ionosphere system. The auroral streamer event studied was simultaneously observed in the conjugate Northern and Southern Hemisphere ionosphere. |
format |
Text |
author |
Amm, O. Nakamura, R. Takada, T. Kauristie, K. Frey, H. U. Owen, C. J. Aikio, A. Kuula, R. |
spellingShingle |
Amm, O. Nakamura, R. Takada, T. Kauristie, K. Frey, H. U. Owen, C. J. Aikio, A. Kuula, R. Observations of an auroral streamer in a double oval configuration |
author_facet |
Amm, O. Nakamura, R. Takada, T. Kauristie, K. Frey, H. U. Owen, C. J. Aikio, A. Kuula, R. |
author_sort |
Amm, O. |
title |
Observations of an auroral streamer in a double oval configuration |
title_short |
Observations of an auroral streamer in a double oval configuration |
title_full |
Observations of an auroral streamer in a double oval configuration |
title_fullStr |
Observations of an auroral streamer in a double oval configuration |
title_full_unstemmed |
Observations of an auroral streamer in a double oval configuration |
title_sort |
observations of an auroral streamer in a double oval configuration |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-29-701-2011 https://angeo.copernicus.org/articles/29/701/2011/ |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-29-701-2011 https://angeo.copernicus.org/articles/29/701/2011/ |
op_doi |
https://doi.org/10.5194/angeo-29-701-2011 |
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Annales Geophysicae |
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29 |
container_issue |
4 |
container_start_page |
701 |
op_container_end_page |
716 |
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1766400397771014144 |