Statistical study of auroral omega bands
The presence of very few statistical studies on auroral omega bands motivated us to test-use a semi-automatic method for identifying large-scale undulations of the diffuse aurora boundary and to investigate their occurrence. Five identical all-sky cameras with overlapping fields of view provided dat...
Published in: | Annales Geophysicae |
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ftcopernicus:oai:publications.copernicus.org:angeo57835 2023-05-15T16:13:01+02:00 Statistical study of auroral omega bands Partamies, Noora Weygand, James M. Juusola, Liisa 2018-09-27 application/pdf https://doi.org/10.5194/angeo-35-1069-2017 https://angeo.copernicus.org/articles/35/1069/2017/ eng eng doi:10.5194/angeo-35-1069-2017 https://angeo.copernicus.org/articles/35/1069/2017/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-35-1069-2017 2020-07-20T16:23:37Z The presence of very few statistical studies on auroral omega bands motivated us to test-use a semi-automatic method for identifying large-scale undulations of the diffuse aurora boundary and to investigate their occurrence. Five identical all-sky cameras with overlapping fields of view provided data for 438 auroral omega-like structures over Fennoscandian Lapland from 1996 to 2007. The results from this set of omega band events agree remarkably well with previous observations of omega band occurrence in magnetic local time (MLT), lifetime, location between the region 1 and 2 field-aligned currents, as well as current density estimates. The average peak emission height of omega forms corresponds to the estimated precipitation energies of a few keV, which experienced no significant change during the events. Analysis of both local and global magnetic indices demonstrates that omega bands are observed during substorm expansion and recovery phases that are more intense than average substorm expansion and recovery phases in the same region. The omega occurrence with respect to the substorm expansion and recovery phases is in a very good agreement with an earlier observed distribution of fast earthward flows in the plasma sheet during expansion and recovery phases. These findings support the theory that omegas are produced by fast earthward flows and auroral streamers, despite the rarity of good conjugate observations. Text Fennoscandian Lapland Copernicus Publications: E-Journals Annales Geophysicae 35 5 1069 1083 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
The presence of very few statistical studies on auroral omega bands motivated us to test-use a semi-automatic method for identifying large-scale undulations of the diffuse aurora boundary and to investigate their occurrence. Five identical all-sky cameras with overlapping fields of view provided data for 438 auroral omega-like structures over Fennoscandian Lapland from 1996 to 2007. The results from this set of omega band events agree remarkably well with previous observations of omega band occurrence in magnetic local time (MLT), lifetime, location between the region 1 and 2 field-aligned currents, as well as current density estimates. The average peak emission height of omega forms corresponds to the estimated precipitation energies of a few keV, which experienced no significant change during the events. Analysis of both local and global magnetic indices demonstrates that omega bands are observed during substorm expansion and recovery phases that are more intense than average substorm expansion and recovery phases in the same region. The omega occurrence with respect to the substorm expansion and recovery phases is in a very good agreement with an earlier observed distribution of fast earthward flows in the plasma sheet during expansion and recovery phases. These findings support the theory that omegas are produced by fast earthward flows and auroral streamers, despite the rarity of good conjugate observations. |
format |
Text |
author |
Partamies, Noora Weygand, James M. Juusola, Liisa |
spellingShingle |
Partamies, Noora Weygand, James M. Juusola, Liisa Statistical study of auroral omega bands |
author_facet |
Partamies, Noora Weygand, James M. Juusola, Liisa |
author_sort |
Partamies, Noora |
title |
Statistical study of auroral omega bands |
title_short |
Statistical study of auroral omega bands |
title_full |
Statistical study of auroral omega bands |
title_fullStr |
Statistical study of auroral omega bands |
title_full_unstemmed |
Statistical study of auroral omega bands |
title_sort |
statistical study of auroral omega bands |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-35-1069-2017 https://angeo.copernicus.org/articles/35/1069/2017/ |
genre |
Fennoscandian Lapland |
genre_facet |
Fennoscandian Lapland |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-35-1069-2017 https://angeo.copernicus.org/articles/35/1069/2017/ |
op_doi |
https://doi.org/10.5194/angeo-35-1069-2017 |
container_title |
Annales Geophysicae |
container_volume |
35 |
container_issue |
5 |
container_start_page |
1069 |
op_container_end_page |
1083 |
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1765998623624003584 |