Observations of nightside auroral plasma upflows in the F-region and topside ionosphere
Observations from the special UK EISCAT program UFIS are presented. UFIS is a joint UHF-VHF experiment, designed to make simultaneous measurements of enhanced vertical plasma flows in the F-region and topside ionospheres. Three distinct intervals of upward ion flow were observed. During the first ev...
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ftleicester:oai:lra.le.ac.uk:2381/36394 2023-05-15T16:04:49+02:00 Observations of nightside auroral plasma upflows in the F-region and topside ionosphere Lester, Mark Foster, C. 2016-01-26T14:17:17Z http://www.ann-geophys.net/14/1274/1996/ http://hdl.handle.net/2381/36394 https://doi.org/10.1007/s00585-996-1274-1 en eng Copernicus Publications on behalf of the European Geosciences Union Annales Geophysicae, 1996, 14, pp. 1274-1283 0992-7689 http://www.ann-geophys.net/14/1274/1996/ http://hdl.handle.net/2381/36394 doi:10.1007/s00585-996-1274-1 1432-0576 Copyright © 1996, European Geosciences Union. This is an open-access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. CC-BY Journal Article Article 2016 ftleicester https://doi.org/10.1007/s00585-996-1274-1 2019-03-22T20:21:21Z Observations from the special UK EISCAT program UFIS are presented. UFIS is a joint UHF-VHF experiment, designed to make simultaneous measurements of enhanced vertical plasma flows in the F-region and topside ionospheres. Three distinct intervals of upward ion flow were observed. During the first event, upward ion fluxes in excess of 10[Superscript: 13] m[Superscript: –2] s[Superscript: –1 ] were detected, with vertical ion velocities reaching 300 m s[Superscript: –1 ] at 800 km. The upflow was associated with the passage of an auroral arc through the radar field of view. In the F-region, an enhanced and sheared convection electric field on the leading edge of the arc resulted in heating of the ions, whilst at higher altitudes, above the precipitation region, strongly enhanced electron temperatures were observed; such features are commonly associated with the generation of plasma upflows. These observations demonstrate some of the acceleration mechanisms which can exist within the small-scale structure of an auroral arc. A later upflow event was associated with enhanced electron temperatures and only a moderate convection electric field, with no indication of significantly elevated ion tem- peratures. There was again some evidence of F-region particle precipitation at the time of the upflow, which exhibited vertical ion velocities of similar magnitude to the earlier upflow, suggesting that the behaviour of the electrons might be the dominant factor in this type of event. A third upflow was detected at altitudes above the observing range of the UHF radar, but which was evident in the VHF data from 600 km upwards. Smaller vertical velocities were observed in this event, which was apparently uncorrelated with any features observed at lower altitudes. Limitations imposed by the experimental conditions inhibit the interpretation of this event, although the upflow was again likely related to topside plasma heating. Peer-reviewed Publisher Version Article in Journal/Newspaper EISCAT University of Leicester: Leicester Research Archive (LRA) Annales Geophysicae 14 12 1274 1283 |
institution |
Open Polar |
collection |
University of Leicester: Leicester Research Archive (LRA) |
op_collection_id |
ftleicester |
language |
English |
description |
Observations from the special UK EISCAT program UFIS are presented. UFIS is a joint UHF-VHF experiment, designed to make simultaneous measurements of enhanced vertical plasma flows in the F-region and topside ionospheres. Three distinct intervals of upward ion flow were observed. During the first event, upward ion fluxes in excess of 10[Superscript: 13] m[Superscript: –2] s[Superscript: –1 ] were detected, with vertical ion velocities reaching 300 m s[Superscript: –1 ] at 800 km. The upflow was associated with the passage of an auroral arc through the radar field of view. In the F-region, an enhanced and sheared convection electric field on the leading edge of the arc resulted in heating of the ions, whilst at higher altitudes, above the precipitation region, strongly enhanced electron temperatures were observed; such features are commonly associated with the generation of plasma upflows. These observations demonstrate some of the acceleration mechanisms which can exist within the small-scale structure of an auroral arc. A later upflow event was associated with enhanced electron temperatures and only a moderate convection electric field, with no indication of significantly elevated ion tem- peratures. There was again some evidence of F-region particle precipitation at the time of the upflow, which exhibited vertical ion velocities of similar magnitude to the earlier upflow, suggesting that the behaviour of the electrons might be the dominant factor in this type of event. A third upflow was detected at altitudes above the observing range of the UHF radar, but which was evident in the VHF data from 600 km upwards. Smaller vertical velocities were observed in this event, which was apparently uncorrelated with any features observed at lower altitudes. Limitations imposed by the experimental conditions inhibit the interpretation of this event, although the upflow was again likely related to topside plasma heating. Peer-reviewed Publisher Version |
format |
Article in Journal/Newspaper |
author |
Lester, Mark Foster, C. |
spellingShingle |
Lester, Mark Foster, C. Observations of nightside auroral plasma upflows in the F-region and topside ionosphere |
author_facet |
Lester, Mark Foster, C. |
author_sort |
Lester, Mark |
title |
Observations of nightside auroral plasma upflows in the F-region and topside ionosphere |
title_short |
Observations of nightside auroral plasma upflows in the F-region and topside ionosphere |
title_full |
Observations of nightside auroral plasma upflows in the F-region and topside ionosphere |
title_fullStr |
Observations of nightside auroral plasma upflows in the F-region and topside ionosphere |
title_full_unstemmed |
Observations of nightside auroral plasma upflows in the F-region and topside ionosphere |
title_sort |
observations of nightside auroral plasma upflows in the f-region and topside ionosphere |
publisher |
Copernicus Publications on behalf of the European Geosciences Union |
publishDate |
2016 |
url |
http://www.ann-geophys.net/14/1274/1996/ http://hdl.handle.net/2381/36394 https://doi.org/10.1007/s00585-996-1274-1 |
genre |
EISCAT |
genre_facet |
EISCAT |
op_relation |
Annales Geophysicae, 1996, 14, pp. 1274-1283 0992-7689 http://www.ann-geophys.net/14/1274/1996/ http://hdl.handle.net/2381/36394 doi:10.1007/s00585-996-1274-1 1432-0576 |
op_rights |
Copyright © 1996, European Geosciences Union. This is an open-access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1007/s00585-996-1274-1 |
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Annales Geophysicae |
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14 |
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12 |
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1274 |
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1283 |
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1766400462952595456 |