Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments
International audience The four Cluster s/c passed over Northern Scandinavia on 6 February 2001 from south-east to north-west at a radial distance of about 4.4 R E in the post-midnight sector. When mapped along geomagnetic field lines, the separation of the spacecraft in the ionosphere was confined...
Published in: | Annales Geophysicae |
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ftuniversailles:oai:HAL:hal-00329410v1 2023-11-12T04:16:38+01:00 Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments Aikio, A. T. Mursula, K. Buchert, S. Forme, F. Amm, O. Marklund, G. Dunlop, M. Fontaine, D. Vaivads, A. Fazakerley, A. University of Oulu Angström Laboratory Uppsala University Centre d'étude des environnements terrestre et planétaires (CETP) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Finnish Meteorological Institute (FMI) Alfven Laboratory KTH Royal Institute of Technology Stockholm (KTH ) Imperial College London Mullard Space Science Laboratory (MSSL) University College of London London (UCL) 2004-12-22 https://hal.science/hal-00329410 https://hal.science/hal-00329410/document https://hal.science/hal-00329410/file/angeo-22-4089-2004.pdf https://doi.org/10.5194/angeo-22-4089-2004 en eng HAL CCSD European Geosciences Union info:eu-repo/semantics/altIdentifier/doi/10.5194/angeo-22-4089-2004 hal-00329410 https://hal.science/hal-00329410 https://hal.science/hal-00329410/document https://hal.science/hal-00329410/file/angeo-22-4089-2004.pdf BIBCODE: 2004AnGeo.22.4089A doi:10.5194/angeo-22-4089-2004 info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00329410 Annales Geophysicae, 2004, 22 (12), pp.4089-4101. ⟨10.5194/angeo-22-4089-2004⟩ [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2004 ftuniversailles https://doi.org/10.5194/angeo-22-4089-2004 2023-10-24T22:39:00Z International audience The four Cluster s/c passed over Northern Scandinavia on 6 February 2001 from south-east to north-west at a radial distance of about 4.4 R E in the post-midnight sector. When mapped along geomagnetic field lines, the separation of the spacecraft in the ionosphere was confined to within 110km in latitude and 50km in longitude. This constellation allowed us to study the temporal evolution of plasma with a time scale of a few minutes. Ground-based instrumentation used involved two all-sky cameras, magnetometers and the EISCAT radar. The main findings were as follows. Two auroral arcs were located close to the equatorward and poleward edge of a large-scale density cavity, respectively. These arcs showed a different kind of a temporal evolution. (1) As a response to a pseudo-breakup onset, both the up- and downward field-aligned current (FAC) sheets associated with the equatorward arc widened and the total amount of FAC doubled in a time scale of 1–2min. (2) In the poleward arc, a density cavity formed in the ionosphere in the return (downward) current region. As a result of ionospheric feedback, a strongly enhanced ionospheric southward electric field developed in the region of decreased Pedersen conductance. Furthermore, the acceleration potential of ionospheric electrons, carrying the return current, increased from 200 to 1000eV in 70s, and the return current region widened in order to supply a constant amount of return current to the arc current circuit. Evidence of local acceleration of the electron population by dispersive Alfvén waves was obtained in the upward FAC region of the poleward arc. However, the downward accelerated suprathermal electrons must be further energised below Cluster in order to be able to produce the observed visible aurora. Both of the auroral arcs were associated with broad-band ULF/ELF (BBELF) waves, but they were highly localised in space and time. The most intense BBELF waves were confined typically to the return current regions adjacent to the visual arc, ... Article in Journal/Newspaper EISCAT Université de Versailles Saint-Quentin-en-Yvelines: HAL-UVSQ Pedersen ENVELOPE(140.013,140.013,-66.668,-66.668) Annales Geophysicae 22 12 4089 4101 |
institution |
Open Polar |
collection |
Université de Versailles Saint-Quentin-en-Yvelines: HAL-UVSQ |
op_collection_id |
ftuniversailles |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Aikio, A. T. Mursula, K. Buchert, S. Forme, F. Amm, O. Marklund, G. Dunlop, M. Fontaine, D. Vaivads, A. Fazakerley, A. Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience The four Cluster s/c passed over Northern Scandinavia on 6 February 2001 from south-east to north-west at a radial distance of about 4.4 R E in the post-midnight sector. When mapped along geomagnetic field lines, the separation of the spacecraft in the ionosphere was confined to within 110km in latitude and 50km in longitude. This constellation allowed us to study the temporal evolution of plasma with a time scale of a few minutes. Ground-based instrumentation used involved two all-sky cameras, magnetometers and the EISCAT radar. The main findings were as follows. Two auroral arcs were located close to the equatorward and poleward edge of a large-scale density cavity, respectively. These arcs showed a different kind of a temporal evolution. (1) As a response to a pseudo-breakup onset, both the up- and downward field-aligned current (FAC) sheets associated with the equatorward arc widened and the total amount of FAC doubled in a time scale of 1–2min. (2) In the poleward arc, a density cavity formed in the ionosphere in the return (downward) current region. As a result of ionospheric feedback, a strongly enhanced ionospheric southward electric field developed in the region of decreased Pedersen conductance. Furthermore, the acceleration potential of ionospheric electrons, carrying the return current, increased from 200 to 1000eV in 70s, and the return current region widened in order to supply a constant amount of return current to the arc current circuit. Evidence of local acceleration of the electron population by dispersive Alfvén waves was obtained in the upward FAC region of the poleward arc. However, the downward accelerated suprathermal electrons must be further energised below Cluster in order to be able to produce the observed visible aurora. Both of the auroral arcs were associated with broad-band ULF/ELF (BBELF) waves, but they were highly localised in space and time. The most intense BBELF waves were confined typically to the return current regions adjacent to the visual arc, ... |
author2 |
University of Oulu Angström Laboratory Uppsala University Centre d'étude des environnements terrestre et planétaires (CETP) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Finnish Meteorological Institute (FMI) Alfven Laboratory KTH Royal Institute of Technology Stockholm (KTH ) Imperial College London Mullard Space Science Laboratory (MSSL) University College of London London (UCL) |
format |
Article in Journal/Newspaper |
author |
Aikio, A. T. Mursula, K. Buchert, S. Forme, F. Amm, O. Marklund, G. Dunlop, M. Fontaine, D. Vaivads, A. Fazakerley, A. |
author_facet |
Aikio, A. T. Mursula, K. Buchert, S. Forme, F. Amm, O. Marklund, G. Dunlop, M. Fontaine, D. Vaivads, A. Fazakerley, A. |
author_sort |
Aikio, A. T. |
title |
Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments |
title_short |
Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments |
title_full |
Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments |
title_fullStr |
Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments |
title_full_unstemmed |
Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments |
title_sort |
temporal evolution of two auroral arcs as measured by the cluster satellite and coordinated ground-based instruments |
publisher |
HAL CCSD |
publishDate |
2004 |
url |
https://hal.science/hal-00329410 https://hal.science/hal-00329410/document https://hal.science/hal-00329410/file/angeo-22-4089-2004.pdf https://doi.org/10.5194/angeo-22-4089-2004 |
long_lat |
ENVELOPE(140.013,140.013,-66.668,-66.668) |
geographic |
Pedersen |
geographic_facet |
Pedersen |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00329410 Annales Geophysicae, 2004, 22 (12), pp.4089-4101. ⟨10.5194/angeo-22-4089-2004⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/angeo-22-4089-2004 hal-00329410 https://hal.science/hal-00329410 https://hal.science/hal-00329410/document https://hal.science/hal-00329410/file/angeo-22-4089-2004.pdf BIBCODE: 2004AnGeo.22.4089A doi:10.5194/angeo-22-4089-2004 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/angeo-22-4089-2004 |
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Annales Geophysicae |
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22 |
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12 |
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4089 |
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