Antiparallel magnetic merging signatures during IMF B Y >>0: longitudinal and latitudinal cusp aurora bifurcations
International audience A prominent dayside auroral event, occurred during an IMF B Y -dominated time interval, and characterized by the contemporaneous longitudinal and latitudinal cusp bifurcations, is reported. The event was recorded the 19 December 2002, between about 09:30?10:45 UT, by the ITACA...
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ftccsdartic:oai:HAL:hal-00318161v1 2023-11-12T04:18:05+01:00 Antiparallel magnetic merging signatures during IMF B Y >>0: longitudinal and latitudinal cusp aurora bifurcations Massetti, S. Istituto di Fisica dello Spazio Interplanetario (IFSI) National Research Council of Italy 2006-09-13 https://hal.science/hal-00318161 https://hal.science/hal-00318161/document https://hal.science/hal-00318161/file/angeo-24-2299-2006.pdf en eng HAL CCSD European Geosciences Union hal-00318161 https://hal.science/hal-00318161 https://hal.science/hal-00318161/document https://hal.science/hal-00318161/file/angeo-24-2299-2006.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00318161 Annales Geophysicae, 2006, 24 (8), pp.2299-2311 [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 2006 ftccsdartic 2023-10-21T23:06:49Z International audience A prominent dayside auroral event, occurred during an IMF B Y -dominated time interval, and characterized by the contemporaneous longitudinal and latitudinal cusp bifurcations, is reported. The event was recorded the 19 December 2002, between about 09:30?10:45 UT, by the ITACA 2 twin auroral monitors system, in the Greenland-Svalbard zone. The splitting of the ionospheric footprint of the geomagnetic cusp, traced by the dayside auroral activity, was recently identified with the signatures of antiparallel reconnection episodes ongoing at different magnetopause locations, during large IMF B Y periods. The first part of the event showed a broad longitudinal bifurcation of the red-dominated cusp aurora, displaced in the prenoon and postnoon, with a separation up to ~1800 km, during northeast directed IMF (clock-angle rotating from 45° to 90°). This observation widens the range of IMF regimes that are known to drive a longitudinal bifurcation of the cusp, since previous case-studies reported these events to occur during southeast/southwest oriented IMF (clock-angle ?135°). The second part of the event, developed when the IMF turned to a nearly horizontal orientation ( B Y >>0, B Z ~0, clock-angle ~90°), and exhibited the simultaneous activation of the cusp auroras in three distinct areas: i) two of them associated to the above-mentioned longitudinally bifurcated cusp (~73°?75° CGM latitude, type 1 cusp aurora), and linked to (near)antiparallel magnetic reconnection patches equatorward the northern and the southern cusp, ii) the other one characterized by isolated high-latitude (~76°?77° CGM latitude, type 2 cusp aurora) rayed arc(s) with intense green emission, and triggered by (near)antiparallel merging at the northern lobe (usually observed during positive IMF B Z ), poleward the local cusp. During this phase, the longitudinal separation of the low-latitude type~1 cusp aurora was about 1000 km wide, with a 500 km gap, while the latitudinal separation between low- (type 1) and ... Article in Journal/Newspaper Greenland Svalbard Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Svalbard Greenland |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
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 Massetti, S. Antiparallel magnetic merging signatures during IMF B Y >>0: longitudinal and latitudinal cusp aurora bifurcations |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience A prominent dayside auroral event, occurred during an IMF B Y -dominated time interval, and characterized by the contemporaneous longitudinal and latitudinal cusp bifurcations, is reported. The event was recorded the 19 December 2002, between about 09:30?10:45 UT, by the ITACA 2 twin auroral monitors system, in the Greenland-Svalbard zone. The splitting of the ionospheric footprint of the geomagnetic cusp, traced by the dayside auroral activity, was recently identified with the signatures of antiparallel reconnection episodes ongoing at different magnetopause locations, during large IMF B Y periods. The first part of the event showed a broad longitudinal bifurcation of the red-dominated cusp aurora, displaced in the prenoon and postnoon, with a separation up to ~1800 km, during northeast directed IMF (clock-angle rotating from 45° to 90°). This observation widens the range of IMF regimes that are known to drive a longitudinal bifurcation of the cusp, since previous case-studies reported these events to occur during southeast/southwest oriented IMF (clock-angle ?135°). The second part of the event, developed when the IMF turned to a nearly horizontal orientation ( B Y >>0, B Z ~0, clock-angle ~90°), and exhibited the simultaneous activation of the cusp auroras in three distinct areas: i) two of them associated to the above-mentioned longitudinally bifurcated cusp (~73°?75° CGM latitude, type 1 cusp aurora), and linked to (near)antiparallel magnetic reconnection patches equatorward the northern and the southern cusp, ii) the other one characterized by isolated high-latitude (~76°?77° CGM latitude, type 2 cusp aurora) rayed arc(s) with intense green emission, and triggered by (near)antiparallel merging at the northern lobe (usually observed during positive IMF B Z ), poleward the local cusp. During this phase, the longitudinal separation of the low-latitude type~1 cusp aurora was about 1000 km wide, with a 500 km gap, while the latitudinal separation between low- (type 1) and ... |
author2 |
Istituto di Fisica dello Spazio Interplanetario (IFSI) National Research Council of Italy |
format |
Article in Journal/Newspaper |
author |
Massetti, S. |
author_facet |
Massetti, S. |
author_sort |
Massetti, S. |
title |
Antiparallel magnetic merging signatures during IMF B Y >>0: longitudinal and latitudinal cusp aurora bifurcations |
title_short |
Antiparallel magnetic merging signatures during IMF B Y >>0: longitudinal and latitudinal cusp aurora bifurcations |
title_full |
Antiparallel magnetic merging signatures during IMF B Y >>0: longitudinal and latitudinal cusp aurora bifurcations |
title_fullStr |
Antiparallel magnetic merging signatures during IMF B Y >>0: longitudinal and latitudinal cusp aurora bifurcations |
title_full_unstemmed |
Antiparallel magnetic merging signatures during IMF B Y >>0: longitudinal and latitudinal cusp aurora bifurcations |
title_sort |
antiparallel magnetic merging signatures during imf b y >>0: longitudinal and latitudinal cusp aurora bifurcations |
publisher |
HAL CCSD |
publishDate |
2006 |
url |
https://hal.science/hal-00318161 https://hal.science/hal-00318161/document https://hal.science/hal-00318161/file/angeo-24-2299-2006.pdf |
geographic |
Svalbard Greenland |
geographic_facet |
Svalbard Greenland |
genre |
Greenland Svalbard |
genre_facet |
Greenland Svalbard |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00318161 Annales Geophysicae, 2006, 24 (8), pp.2299-2311 |
op_relation |
hal-00318161 https://hal.science/hal-00318161 https://hal.science/hal-00318161/document https://hal.science/hal-00318161/file/angeo-24-2299-2006.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782334789576032256 |