A multipoint study of a substorm occurring on 7 December, 1992, and its theoretical implications
On 7 December 1992, a moderate substorm was observed by a variety of satellites and ground-based instruments. Ionospheric flows were monitored near dusk by the Goose Bay HF radar and near midnight by the EISCAT radar. The observed flows are compared here with magnetometer observations by the IMAGE a...
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ftdoajarticles:oai:doaj.org/article:bf64dc004fd842059d09269709ba9525 2023-05-15T16:04:47+02:00 A multipoint study of a substorm occurring on 7 December, 1992, and its theoretical implications N. J. Fox S. W. H. Cowley V. N. Davda G. Enno E. Friis-Christensen R. A. Greenwald M. R. Hairston M. Lester M. Lockwood H. Lühr D. K. Milling J. S. Murphree M. Pinnock G. D. Reeves 1999-11-01T00:00:00Z https://doi.org/10.1007/s00585-999-1369-6 https://doaj.org/article/bf64dc004fd842059d09269709ba9525 EN eng Copernicus Publications https://www.ann-geophys.net/17/1369/1999/angeo-17-1369-1999.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-999-1369-6 0992-7689 1432-0576 https://doaj.org/article/bf64dc004fd842059d09269709ba9525 Annales Geophysicae, Vol 17, Pp 1369-1384 (1999) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 1999 ftdoajarticles https://doi.org/10.1007/s00585-999-1369-6 2022-12-31T14:11:04Z On 7 December 1992, a moderate substorm was observed by a variety of satellites and ground-based instruments. Ionospheric flows were monitored near dusk by the Goose Bay HF radar and near midnight by the EISCAT radar. The observed flows are compared here with magnetometer observations by the IMAGE array in Scandinavia and the two Greenland chains, the auroral distribution observed by Freja and the substorm cycle observations by the SABRE radar, the SAMNET magnetometer array and LANL geosynchronous satellites. Data from Galileo Earth-encounter II are used to estimate the IMF B z component. The data presented show that the substorm onset electrojet at midnight was confined to closed field lines equatorward of the pre-existing convection reversal boundaries observed in the dusk and midnight regions. No evidence of substantial closure of open flux was detected following this substorm onset. Indeed the convection reversal boundary on the duskside continued to expand equatorward after onset due to the continued presence of strong southward IMF, such that growth and expansion phase features were simultaneously present. Clear indications of closure of open flux were not observed until a subsequent substorm intensification 25 min after the initial onset. After this time, the substorm auroral bulge in the nightside hours propagated well poleward of the pre-existing convection reversal boundary, and strong flow perturbations were observed by the Goose Bay radar, indicative of flows driven by reconnection in the tail. Key words. Ionosphere (auroral ionosphere; plasma convection) · Magnetospheric physics (storms and substorms) Article in Journal/Newspaper EISCAT Greenland Directory of Open Access Journals: DOAJ Articles Greenland Annales Geophysicae 17 11 1369 1384 |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 N. J. Fox S. W. H. Cowley V. N. Davda G. Enno E. Friis-Christensen R. A. Greenwald M. R. Hairston M. Lester M. Lockwood H. Lühr D. K. Milling J. S. Murphree M. Pinnock G. D. Reeves A multipoint study of a substorm occurring on 7 December, 1992, and its theoretical implications |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
On 7 December 1992, a moderate substorm was observed by a variety of satellites and ground-based instruments. Ionospheric flows were monitored near dusk by the Goose Bay HF radar and near midnight by the EISCAT radar. The observed flows are compared here with magnetometer observations by the IMAGE array in Scandinavia and the two Greenland chains, the auroral distribution observed by Freja and the substorm cycle observations by the SABRE radar, the SAMNET magnetometer array and LANL geosynchronous satellites. Data from Galileo Earth-encounter II are used to estimate the IMF B z component. The data presented show that the substorm onset electrojet at midnight was confined to closed field lines equatorward of the pre-existing convection reversal boundaries observed in the dusk and midnight regions. No evidence of substantial closure of open flux was detected following this substorm onset. Indeed the convection reversal boundary on the duskside continued to expand equatorward after onset due to the continued presence of strong southward IMF, such that growth and expansion phase features were simultaneously present. Clear indications of closure of open flux were not observed until a subsequent substorm intensification 25 min after the initial onset. After this time, the substorm auroral bulge in the nightside hours propagated well poleward of the pre-existing convection reversal boundary, and strong flow perturbations were observed by the Goose Bay radar, indicative of flows driven by reconnection in the tail. Key words. Ionosphere (auroral ionosphere; plasma convection) · Magnetospheric physics (storms and substorms) |
format |
Article in Journal/Newspaper |
author |
N. J. Fox S. W. H. Cowley V. N. Davda G. Enno E. Friis-Christensen R. A. Greenwald M. R. Hairston M. Lester M. Lockwood H. Lühr D. K. Milling J. S. Murphree M. Pinnock G. D. Reeves |
author_facet |
N. J. Fox S. W. H. Cowley V. N. Davda G. Enno E. Friis-Christensen R. A. Greenwald M. R. Hairston M. Lester M. Lockwood H. Lühr D. K. Milling J. S. Murphree M. Pinnock G. D. Reeves |
author_sort |
N. J. Fox |
title |
A multipoint study of a substorm occurring on 7 December, 1992, and its theoretical implications |
title_short |
A multipoint study of a substorm occurring on 7 December, 1992, and its theoretical implications |
title_full |
A multipoint study of a substorm occurring on 7 December, 1992, and its theoretical implications |
title_fullStr |
A multipoint study of a substorm occurring on 7 December, 1992, and its theoretical implications |
title_full_unstemmed |
A multipoint study of a substorm occurring on 7 December, 1992, and its theoretical implications |
title_sort |
multipoint study of a substorm occurring on 7 december, 1992, and its theoretical implications |
publisher |
Copernicus Publications |
publishDate |
1999 |
url |
https://doi.org/10.1007/s00585-999-1369-6 https://doaj.org/article/bf64dc004fd842059d09269709ba9525 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
EISCAT Greenland |
genre_facet |
EISCAT Greenland |
op_source |
Annales Geophysicae, Vol 17, Pp 1369-1384 (1999) |
op_relation |
https://www.ann-geophys.net/17/1369/1999/angeo-17-1369-1999.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-999-1369-6 0992-7689 1432-0576 https://doaj.org/article/bf64dc004fd842059d09269709ba9525 |
op_doi |
https://doi.org/10.1007/s00585-999-1369-6 |
container_title |
Annales Geophysicae |
container_volume |
17 |
container_issue |
11 |
container_start_page |
1369 |
op_container_end_page |
1384 |
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1766400412710076416 |