Fine-scale dynamics of fragmented aurora-like emissions
Fragmented aurora-like emissions (FAEs) are small (few kilometres) optical structures which have been observed close to the poleward boundary of the aurora from the high-latitude location of Svalbard (magnetic latitude 75.3 N). The FAEs are only visible in certain emissions, and their shape has no m...
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ftsouthampton:oai:eprints.soton.ac.uk:452171 2023-12-03T10:31:01+01:00 Fine-scale dynamics of fragmented aurora-like emissions Whiter, Daniel Sundberg, Hanna Lanchester, Betty Dreyer, Joshua Partamies, Noora Ivchenko, Nickolay Zaccaria Di Fraia, Marco Oliver, Rosie Serpell-Stevens, Amanda Shaw-Diaz, Tiffany Braunersreuther, Thomas 2021-11-25 text https://eprints.soton.ac.uk/452171/ https://eprints.soton.ac.uk/452171/1/angeo_2020_95_manuscript_version4.pdf en English eng https://eprints.soton.ac.uk/452171/1/angeo_2020_95_manuscript_version4.pdf Whiter, Daniel, Sundberg, Hanna, Lanchester, Betty, Dreyer, Joshua, Partamies, Noora, Ivchenko, Nickolay, Zaccaria Di Fraia, Marco, Oliver, Rosie, Serpell-Stevens, Amanda, Shaw-Diaz, Tiffany and Braunersreuther, Thomas (2021) Fine-scale dynamics of fragmented aurora-like emissions. Annales Geophysicae, 39 (6), 975-989. (doi:10.5194/angeo-39-975-2021 <http://dx.doi.org/10.5194/angeo-39-975-2021>). cc_by_4 Article PeerReviewed 2021 ftsouthampton https://doi.org/10.5194/angeo-39-975-2021 2023-11-03T00:02:36Z Fragmented aurora-like emissions (FAEs) are small (few kilometres) optical structures which have been observed close to the poleward boundary of the aurora from the high-latitude location of Svalbard (magnetic latitude 75.3 N). The FAEs are only visible in certain emissions, and their shape has no magnetic-field-aligned component, suggesting that they are not caused by energetic particle precipitation and are, therefore, not aurora in the normal sense of the word. The FAEs sometimes form wave-like structures parallel to an auroral arc, with regular spacing between each FAE. They drift at a constant speed and exhibit internal dynamics moving at a faster speed than the envelope structure. The formation mechanism of FAEs is currently unknown. We present an analysis of high-resolution optical observations of FAEs made during two separate events. Based on their appearance and dynamics, we make the assumption that the FAEs are a signature of a dispersive wave in the lower E-region ionosphere, co-located with enhanced electron and ion temperatures detected by incoherent scatter radar. Their drift speed (group speed) is found to be 580-700 m s-1, and the speed of their internal dynamics (phase speed) is found to be 2200-2500 m s-1, both for an assumed altitude of 100 km. The speeds are similar for both events which are observed during different auroral conditions. We consider two possible waves which could produce the FAEs, i.e. electrostatic ion cyclotron waves (EIC) and Farley-Buneman waves, and find that the observations could be consistent with either wave under certain assumptions. In the case of EIC waves, the FAEs must be located at an altitude above about 140 km, and our measured speeds scaled accordingly. In the case of Farley-Buneman waves a very strong electric field of about 365 mV m-1 is required to produce the observed speeds of the FAEs; such a strong electric field may be a requirement for FAEs to occur. Article in Journal/Newspaper Svalbard University of Southampton: e-Prints Soton Svalbard Farley ENVELOPE(-152.500,-152.500,-86.583,-86.583) Annales Geophysicae 39 6 975 989 |
institution |
Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
English |
description |
Fragmented aurora-like emissions (FAEs) are small (few kilometres) optical structures which have been observed close to the poleward boundary of the aurora from the high-latitude location of Svalbard (magnetic latitude 75.3 N). The FAEs are only visible in certain emissions, and their shape has no magnetic-field-aligned component, suggesting that they are not caused by energetic particle precipitation and are, therefore, not aurora in the normal sense of the word. The FAEs sometimes form wave-like structures parallel to an auroral arc, with regular spacing between each FAE. They drift at a constant speed and exhibit internal dynamics moving at a faster speed than the envelope structure. The formation mechanism of FAEs is currently unknown. We present an analysis of high-resolution optical observations of FAEs made during two separate events. Based on their appearance and dynamics, we make the assumption that the FAEs are a signature of a dispersive wave in the lower E-region ionosphere, co-located with enhanced electron and ion temperatures detected by incoherent scatter radar. Their drift speed (group speed) is found to be 580-700 m s-1, and the speed of their internal dynamics (phase speed) is found to be 2200-2500 m s-1, both for an assumed altitude of 100 km. The speeds are similar for both events which are observed during different auroral conditions. We consider two possible waves which could produce the FAEs, i.e. electrostatic ion cyclotron waves (EIC) and Farley-Buneman waves, and find that the observations could be consistent with either wave under certain assumptions. In the case of EIC waves, the FAEs must be located at an altitude above about 140 km, and our measured speeds scaled accordingly. In the case of Farley-Buneman waves a very strong electric field of about 365 mV m-1 is required to produce the observed speeds of the FAEs; such a strong electric field may be a requirement for FAEs to occur. |
format |
Article in Journal/Newspaper |
author |
Whiter, Daniel Sundberg, Hanna Lanchester, Betty Dreyer, Joshua Partamies, Noora Ivchenko, Nickolay Zaccaria Di Fraia, Marco Oliver, Rosie Serpell-Stevens, Amanda Shaw-Diaz, Tiffany Braunersreuther, Thomas |
spellingShingle |
Whiter, Daniel Sundberg, Hanna Lanchester, Betty Dreyer, Joshua Partamies, Noora Ivchenko, Nickolay Zaccaria Di Fraia, Marco Oliver, Rosie Serpell-Stevens, Amanda Shaw-Diaz, Tiffany Braunersreuther, Thomas Fine-scale dynamics of fragmented aurora-like emissions |
author_facet |
Whiter, Daniel Sundberg, Hanna Lanchester, Betty Dreyer, Joshua Partamies, Noora Ivchenko, Nickolay Zaccaria Di Fraia, Marco Oliver, Rosie Serpell-Stevens, Amanda Shaw-Diaz, Tiffany Braunersreuther, Thomas |
author_sort |
Whiter, Daniel |
title |
Fine-scale dynamics of fragmented aurora-like emissions |
title_short |
Fine-scale dynamics of fragmented aurora-like emissions |
title_full |
Fine-scale dynamics of fragmented aurora-like emissions |
title_fullStr |
Fine-scale dynamics of fragmented aurora-like emissions |
title_full_unstemmed |
Fine-scale dynamics of fragmented aurora-like emissions |
title_sort |
fine-scale dynamics of fragmented aurora-like emissions |
publishDate |
2021 |
url |
https://eprints.soton.ac.uk/452171/ https://eprints.soton.ac.uk/452171/1/angeo_2020_95_manuscript_version4.pdf |
long_lat |
ENVELOPE(-152.500,-152.500,-86.583,-86.583) |
geographic |
Svalbard Farley |
geographic_facet |
Svalbard Farley |
genre |
Svalbard |
genre_facet |
Svalbard |
op_relation |
https://eprints.soton.ac.uk/452171/1/angeo_2020_95_manuscript_version4.pdf Whiter, Daniel, Sundberg, Hanna, Lanchester, Betty, Dreyer, Joshua, Partamies, Noora, Ivchenko, Nickolay, Zaccaria Di Fraia, Marco, Oliver, Rosie, Serpell-Stevens, Amanda, Shaw-Diaz, Tiffany and Braunersreuther, Thomas (2021) Fine-scale dynamics of fragmented aurora-like emissions. Annales Geophysicae, 39 (6), 975-989. (doi:10.5194/angeo-39-975-2021 <http://dx.doi.org/10.5194/angeo-39-975-2021>). |
op_rights |
cc_by_4 |
op_doi |
https://doi.org/10.5194/angeo-39-975-2021 |
container_title |
Annales Geophysicae |
container_volume |
39 |
container_issue |
6 |
container_start_page |
975 |
op_container_end_page |
989 |
_version_ |
1784257146770161664 |