A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora
A poleward-progressing 630 nm optical feature is observed between approximately 0100 UT and 0230 UT (0400 MLT to 0530 MLT) by a meridian-scanning photometer (MSP) located at Ny Ålesund, Svalbard. Simultaneous coherent HF radar measurements indicate a region of poleward-expanding backscatter with rap...
Published in: | Annales Geophysicae |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Springer Verlag
1997
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Online Access: | https://doi.org/10.1007/s00585-997-1388-0 https://noa.gwlb.de/receive/cop_mods_00037433 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00037387/angeo-15-1388-1997.pdf https://angeo.copernicus.org/articles/15/1388/1997/angeo-15-1388-1997.pdf |
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00037433 2023-05-15T17:48:28+02:00 A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora Milan, S. E. Lester, M. Moen, J. 1997-11 electronic https://doi.org/10.1007/s00585-997-1388-0 https://noa.gwlb.de/receive/cop_mods_00037433 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00037387/angeo-15-1388-1997.pdf https://angeo.copernicus.org/articles/15/1388/1997/angeo-15-1388-1997.pdf eng eng Springer Verlag Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.1007/s00585-997-1388-0 https://noa.gwlb.de/receive/cop_mods_00037433 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00037387/angeo-15-1388-1997.pdf https://angeo.copernicus.org/articles/15/1388/1997/angeo-15-1388-1997.pdf https://open-access.net/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 1997 ftnonlinearchiv https://doi.org/10.1007/s00585-997-1388-0 2022-02-08T22:43:31Z A poleward-progressing 630 nm optical feature is observed between approximately 0100 UT and 0230 UT (0400 MLT to 0530 MLT) by a meridian-scanning photometer (MSP) located at Ny Ålesund, Svalbard. Simultaneous coherent HF radar measurements indicate a region of poleward-expanding backscatter with rapid sunward plasma flow velocity along the MSP meridian. Spatial maps of the backscatter indicate a stationary backscatter feature aligned obliquely with respect to the MSP meridian, which produces an impression of poleward-expansion as the MSP progresses to later MLT. Two interpretations of the observations are possible, depending on whether the arc system is considered to move (time-dependent) or to be stationary in time and apparent motion is produced as the MSP meridian rotates underneath it (time-independent). The first interpretation is as a poleward motion of an east-west aligned auroral arc. In this case the appearance of the region of backscatter is not associated with the optical feature, though the velocities within it are enhanced when the two are co-located. The second interpretation is as a polar arc or theta aurora, common features of the polar cap under the prevailing IMF northwards conditions. In this case the backscatter appears as an approximately 150 km wide region adjacent to the optical arc. In both interpretations the luminosity of the optical feature appears related to the magnitude of the plasma flow velocity. The optical features presented here do not generate appreciable HF coherent backscatter, and are only identifiable in the backscatter data as a modification of the flow by the arc electrodynamics. Article in Journal/Newspaper Ny Ålesund Ny-Ålesund Svalbard Niedersächsisches Online-Archiv NOA Ny-Ålesund Svalbard Annales Geophysicae 15 11 1388 1398 |
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Open Polar |
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Niedersächsisches Online-Archiv NOA |
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ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
spellingShingle |
article Verlagsveröffentlichung Milan, S. E. Lester, M. Moen, J. A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora |
topic_facet |
article Verlagsveröffentlichung |
description |
A poleward-progressing 630 nm optical feature is observed between approximately 0100 UT and 0230 UT (0400 MLT to 0530 MLT) by a meridian-scanning photometer (MSP) located at Ny Ålesund, Svalbard. Simultaneous coherent HF radar measurements indicate a region of poleward-expanding backscatter with rapid sunward plasma flow velocity along the MSP meridian. Spatial maps of the backscatter indicate a stationary backscatter feature aligned obliquely with respect to the MSP meridian, which produces an impression of poleward-expansion as the MSP progresses to later MLT. Two interpretations of the observations are possible, depending on whether the arc system is considered to move (time-dependent) or to be stationary in time and apparent motion is produced as the MSP meridian rotates underneath it (time-independent). The first interpretation is as a poleward motion of an east-west aligned auroral arc. In this case the appearance of the region of backscatter is not associated with the optical feature, though the velocities within it are enhanced when the two are co-located. The second interpretation is as a polar arc or theta aurora, common features of the polar cap under the prevailing IMF northwards conditions. In this case the backscatter appears as an approximately 150 km wide region adjacent to the optical arc. In both interpretations the luminosity of the optical feature appears related to the magnitude of the plasma flow velocity. The optical features presented here do not generate appreciable HF coherent backscatter, and are only identifiable in the backscatter data as a modification of the flow by the arc electrodynamics. |
format |
Article in Journal/Newspaper |
author |
Milan, S. E. Lester, M. Moen, J. |
author_facet |
Milan, S. E. Lester, M. Moen, J. |
author_sort |
Milan, S. E. |
title |
A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora |
title_short |
A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora |
title_full |
A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora |
title_fullStr |
A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora |
title_full_unstemmed |
A comparison of optical and coherent HF radar backscatter observations of a post-midnight aurora |
title_sort |
comparison of optical and coherent hf radar backscatter observations of a post-midnight aurora |
publisher |
Springer Verlag |
publishDate |
1997 |
url |
https://doi.org/10.1007/s00585-997-1388-0 https://noa.gwlb.de/receive/cop_mods_00037433 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00037387/angeo-15-1388-1997.pdf https://angeo.copernicus.org/articles/15/1388/1997/angeo-15-1388-1997.pdf |
geographic |
Ny-Ålesund Svalbard |
geographic_facet |
Ny-Ålesund Svalbard |
genre |
Ny Ålesund Ny-Ålesund Svalbard |
genre_facet |
Ny Ålesund Ny-Ålesund Svalbard |
op_relation |
Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.1007/s00585-997-1388-0 https://noa.gwlb.de/receive/cop_mods_00037433 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00037387/angeo-15-1388-1997.pdf https://angeo.copernicus.org/articles/15/1388/1997/angeo-15-1388-1997.pdf |
op_rights |
https://open-access.net/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1007/s00585-997-1388-0 |
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Annales Geophysicae |
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15 |
container_issue |
11 |
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1388 |
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1398 |
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