Deriving the normalised ion-neutral collision frequency from EISCAT observations
Common programme observations by the EISCAT UHF radar revealed an extended interval, post geomagnetic local noon on 03 April 1992, during which the F-region ion velocity orthogonal to the geomagnetic field was significantly enhanced, to values exceeding 2 km s–1 corresponding to a perpendicular elec...
Published in: | Annales Geophysicae |
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European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)
2012
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Online Access: | http://hdl.handle.net/2381/18234 http://www.ann-geophys.net/15/1557/1997/angeo-15-1557-1997.html https://doi.org/10.1007/s005850050570 |
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ftleicester:oai:lra.le.ac.uk:2381/18234 2023-05-15T16:04:35+02:00 Deriving the normalised ion-neutral collision frequency from EISCAT observations Davies, J. A. Lester, M. Robinson, T. R. 2012-10-24T09:04:57Z http://hdl.handle.net/2381/18234 http://www.ann-geophys.net/15/1557/1997/angeo-15-1557-1997.html https://doi.org/10.1007/s005850050570 English eng European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany) ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, 1997, 15 (12), pp. 1557-1569 0992-7689 http://hdl.handle.net/2381/18234 http://www.ann-geophys.net/15/1557/1997/angeo-15-1557-1997.html doi:10.1007/s005850050570 1432-0576 Archived with reference to SHERPA/RoMEO and publisher website. © European Geosciences Union 1997. Version of record: http://www.ann-geophys.net/15/1557/1997/angeo-15-1557-1997.html Web of Science http://webofknowledge.com Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology POLAR-E-REGION INCOHERENT-SCATTER MEASUREMENTS FRICTIONAL HEATING EVENTS UNSTABLE PLASMA-WAVES LOWER THERMOSPHERE HIGH-LATITUDE AURORAL IONOSPHERE SEMIDIURNAL TIDE ELECTRIC-FIELD F-REGION Journal Article 2012 ftleicester https://doi.org/10.1007/s005850050570 2019-03-22T20:16:39Z Common programme observations by the EISCAT UHF radar revealed an extended interval, post geomagnetic local noon on 03 April 1992, during which the F-region ion velocity orthogonal to the geomagnetic field was significantly enhanced, to values exceeding 2 km s–1 corresponding to a perpendicular electric field of some 100 mV m–1. Observations from this interval are used to illustrate a method by which estimates of the E-region ion-neutral collision frequency may be derived in the presence of enhanced electric field. From both the rotation of the ion velocity vector and the reduction in the ion velocity magnitude relative to that in the F-region, independent estimates of the normalised ion-neutral collision frequency are made at the UHF E-region tristatic altitudes; the derived values are, in general, lower than model predictions. Although initial calculations assume a stationary neutral atmosphere, first-order estimates of the E-region neutral wind are subsequently employed to calculate revised estimates of the normalised ion-neutral collision frequency; these neutral winds are derived by attributing the difference between predicted and observed enhancements in field-parallel ion temperature to thermospheric motion. The inclusion of neutral winds, which are themselves not inconsiderable, appears to have only a limited effect on the normalised collision frequencies derived. 41857 Article in Journal/Newspaper EISCAT University of Leicester: Leicester Research Archive (LRA) Annales Geophysicae 15 12 1557 |
institution |
Open Polar |
collection |
University of Leicester: Leicester Research Archive (LRA) |
op_collection_id |
ftleicester |
language |
English |
topic |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology POLAR-E-REGION INCOHERENT-SCATTER MEASUREMENTS FRICTIONAL HEATING EVENTS UNSTABLE PLASMA-WAVES LOWER THERMOSPHERE HIGH-LATITUDE AURORAL IONOSPHERE SEMIDIURNAL TIDE ELECTRIC-FIELD F-REGION |
spellingShingle |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology POLAR-E-REGION INCOHERENT-SCATTER MEASUREMENTS FRICTIONAL HEATING EVENTS UNSTABLE PLASMA-WAVES LOWER THERMOSPHERE HIGH-LATITUDE AURORAL IONOSPHERE SEMIDIURNAL TIDE ELECTRIC-FIELD F-REGION Davies, J. A. Lester, M. Robinson, T. R. Deriving the normalised ion-neutral collision frequency from EISCAT observations |
topic_facet |
Science & Technology Physical Sciences Astronomy & Astrophysics Geosciences Multidisciplinary Meteorology & Atmospheric Sciences Geology POLAR-E-REGION INCOHERENT-SCATTER MEASUREMENTS FRICTIONAL HEATING EVENTS UNSTABLE PLASMA-WAVES LOWER THERMOSPHERE HIGH-LATITUDE AURORAL IONOSPHERE SEMIDIURNAL TIDE ELECTRIC-FIELD F-REGION |
description |
Common programme observations by the EISCAT UHF radar revealed an extended interval, post geomagnetic local noon on 03 April 1992, during which the F-region ion velocity orthogonal to the geomagnetic field was significantly enhanced, to values exceeding 2 km s–1 corresponding to a perpendicular electric field of some 100 mV m–1. Observations from this interval are used to illustrate a method by which estimates of the E-region ion-neutral collision frequency may be derived in the presence of enhanced electric field. From both the rotation of the ion velocity vector and the reduction in the ion velocity magnitude relative to that in the F-region, independent estimates of the normalised ion-neutral collision frequency are made at the UHF E-region tristatic altitudes; the derived values are, in general, lower than model predictions. Although initial calculations assume a stationary neutral atmosphere, first-order estimates of the E-region neutral wind are subsequently employed to calculate revised estimates of the normalised ion-neutral collision frequency; these neutral winds are derived by attributing the difference between predicted and observed enhancements in field-parallel ion temperature to thermospheric motion. The inclusion of neutral winds, which are themselves not inconsiderable, appears to have only a limited effect on the normalised collision frequencies derived. 41857 |
format |
Article in Journal/Newspaper |
author |
Davies, J. A. Lester, M. Robinson, T. R. |
author_facet |
Davies, J. A. Lester, M. Robinson, T. R. |
author_sort |
Davies, J. A. |
title |
Deriving the normalised ion-neutral collision frequency from EISCAT observations |
title_short |
Deriving the normalised ion-neutral collision frequency from EISCAT observations |
title_full |
Deriving the normalised ion-neutral collision frequency from EISCAT observations |
title_fullStr |
Deriving the normalised ion-neutral collision frequency from EISCAT observations |
title_full_unstemmed |
Deriving the normalised ion-neutral collision frequency from EISCAT observations |
title_sort |
deriving the normalised ion-neutral collision frequency from eiscat observations |
publisher |
European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany) |
publishDate |
2012 |
url |
http://hdl.handle.net/2381/18234 http://www.ann-geophys.net/15/1557/1997/angeo-15-1557-1997.html https://doi.org/10.1007/s005850050570 |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
Web of Science http://webofknowledge.com |
op_relation |
ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, 1997, 15 (12), pp. 1557-1569 0992-7689 http://hdl.handle.net/2381/18234 http://www.ann-geophys.net/15/1557/1997/angeo-15-1557-1997.html doi:10.1007/s005850050570 1432-0576 |
op_rights |
Archived with reference to SHERPA/RoMEO and publisher website. © European Geosciences Union 1997. Version of record: http://www.ann-geophys.net/15/1557/1997/angeo-15-1557-1997.html |
op_doi |
https://doi.org/10.1007/s005850050570 |
container_title |
Annales Geophysicae |
container_volume |
15 |
container_issue |
12 |
container_start_page |
1557 |
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1766400190727585792 |