Detailed dayside auroral morphology as a function of local time for southeast IMF orientation: implications for solar wind-magnetosphere coupling
International audience In two case studies we elaborate on spatial and temporal structures of the dayside aurora within 08:00-16:00 magnetic local time (MLT) and discuss the relationship of this structure to solar wind-magnetosphere interconnection topology and the different stages of evolution of o...
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ftinsu:oai:HAL:hal-00317693v1 2023-11-12T04:23:34+01:00 Detailed dayside auroral morphology as a function of local time for southeast IMF orientation: implications for solar wind-magnetosphere coupling Sandholt, P. E. Farrugia, C. J. Denig, W. F. Department of Physics Okayama University EOS Space Science Center Durham University of New Hampshire (UNH) AFRL Space Vehicles Directorate Air Force Research Laboratory (AFRL) United States Air Force (USAF)-United States Air Force (USAF) 2004-11-03 https://hal.science/hal-00317693 https://hal.science/hal-00317693/document https://hal.science/hal-00317693/file/angeo-22-3537-2004.pdf en eng HAL CCSD European Geosciences Union hal-00317693 https://hal.science/hal-00317693 https://hal.science/hal-00317693/document https://hal.science/hal-00317693/file/angeo-22-3537-2004.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317693 Annales Geophysicae, 2004, 22 (10), pp.3537-3560 [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 ftinsu 2023-10-25T16:25:13Z International audience In two case studies we elaborate on spatial and temporal structures of the dayside aurora within 08:00-16:00 magnetic local time (MLT) and discuss the relationship of this structure to solar wind-magnetosphere interconnection topology and the different stages of evolution of open field lines in the Dungey convection cycle. The detailed 2-D auroral morphology is obtained from continuous ground observations at Ny Ålesund (76° magnetic latitude (MLAT)), Svalbard during two days when the interplanetary magnetic field (IMF) is directed southeast ( B y >0 B z <0 ). The auroral activity consists of the successive activations of the following forms: (i) latitudinally separated, sunward moving, arcs/bands of dayside boundary plasma sheet (BPS) origin, in the prenoon (08:00-11:00 MLT) and postnoon (12:00-16:00 MLT) sectors, within 70-75° MLAT, (ii) poleward moving auroral forms (PMAFs) emanating from the pre- and postnoon brightening events, and (iii) a specific activity appearing in the 07:00-10:00 MLT/75-80° MLAT during the prevailing IMF B y >0 conditions. The pre- and postnoon activations are separated by a region of strongly attenuated auroral activity/intensity within the 11:00-12:00 MLT sector, often referred to as the midday gap aurora. The latter aurora is attributed to the presence of component reconnection at the subsolar magnetopause where the stagnant magnetosheath flow lead to field-aligned currents (FACs) which are of only moderate intensity. The much more active and intense aurorae in the prenoon (07:00-11:00 MLT) and postnoon (12:00-16:00 MLT) sectors originate in magnetopause reconnection events that are initiated well away from the subsolar point. The high-latitude auroral activity in the prenoon sector (feature iii) is found to be accompanied by a convection channel at the polar cap boundary. The associated ground magnetic deflection (DPY) is a Svalgaard-Mansurov effect. The convection channel is attributed to effective momentum transfer from the solar ... Article in Journal/Newspaper Ny Ålesund Ny-Ålesund Svalbard Institut national des sciences de l'Univers: HAL-INSU Ny-Ålesund Svalbard |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
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 Sandholt, P. E. Farrugia, C. J. Denig, W. F. Detailed dayside auroral morphology as a function of local time for southeast IMF orientation: implications for solar wind-magnetosphere coupling |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience In two case studies we elaborate on spatial and temporal structures of the dayside aurora within 08:00-16:00 magnetic local time (MLT) and discuss the relationship of this structure to solar wind-magnetosphere interconnection topology and the different stages of evolution of open field lines in the Dungey convection cycle. The detailed 2-D auroral morphology is obtained from continuous ground observations at Ny Ålesund (76° magnetic latitude (MLAT)), Svalbard during two days when the interplanetary magnetic field (IMF) is directed southeast ( B y >0 B z <0 ). The auroral activity consists of the successive activations of the following forms: (i) latitudinally separated, sunward moving, arcs/bands of dayside boundary plasma sheet (BPS) origin, in the prenoon (08:00-11:00 MLT) and postnoon (12:00-16:00 MLT) sectors, within 70-75° MLAT, (ii) poleward moving auroral forms (PMAFs) emanating from the pre- and postnoon brightening events, and (iii) a specific activity appearing in the 07:00-10:00 MLT/75-80° MLAT during the prevailing IMF B y >0 conditions. The pre- and postnoon activations are separated by a region of strongly attenuated auroral activity/intensity within the 11:00-12:00 MLT sector, often referred to as the midday gap aurora. The latter aurora is attributed to the presence of component reconnection at the subsolar magnetopause where the stagnant magnetosheath flow lead to field-aligned currents (FACs) which are of only moderate intensity. The much more active and intense aurorae in the prenoon (07:00-11:00 MLT) and postnoon (12:00-16:00 MLT) sectors originate in magnetopause reconnection events that are initiated well away from the subsolar point. The high-latitude auroral activity in the prenoon sector (feature iii) is found to be accompanied by a convection channel at the polar cap boundary. The associated ground magnetic deflection (DPY) is a Svalgaard-Mansurov effect. The convection channel is attributed to effective momentum transfer from the solar ... |
author2 |
Department of Physics Okayama University EOS Space Science Center Durham University of New Hampshire (UNH) AFRL Space Vehicles Directorate Air Force Research Laboratory (AFRL) United States Air Force (USAF)-United States Air Force (USAF) |
format |
Article in Journal/Newspaper |
author |
Sandholt, P. E. Farrugia, C. J. Denig, W. F. |
author_facet |
Sandholt, P. E. Farrugia, C. J. Denig, W. F. |
author_sort |
Sandholt, P. E. |
title |
Detailed dayside auroral morphology as a function of local time for southeast IMF orientation: implications for solar wind-magnetosphere coupling |
title_short |
Detailed dayside auroral morphology as a function of local time for southeast IMF orientation: implications for solar wind-magnetosphere coupling |
title_full |
Detailed dayside auroral morphology as a function of local time for southeast IMF orientation: implications for solar wind-magnetosphere coupling |
title_fullStr |
Detailed dayside auroral morphology as a function of local time for southeast IMF orientation: implications for solar wind-magnetosphere coupling |
title_full_unstemmed |
Detailed dayside auroral morphology as a function of local time for southeast IMF orientation: implications for solar wind-magnetosphere coupling |
title_sort |
detailed dayside auroral morphology as a function of local time for southeast imf orientation: implications for solar wind-magnetosphere coupling |
publisher |
HAL CCSD |
publishDate |
2004 |
url |
https://hal.science/hal-00317693 https://hal.science/hal-00317693/document https://hal.science/hal-00317693/file/angeo-22-3537-2004.pdf |
geographic |
Ny-Ålesund Svalbard |
geographic_facet |
Ny-Ålesund Svalbard |
genre |
Ny Ålesund Ny-Ålesund Svalbard |
genre_facet |
Ny Ålesund Ny-Ålesund Svalbard |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317693 Annales Geophysicae, 2004, 22 (10), pp.3537-3560 |
op_relation |
hal-00317693 https://hal.science/hal-00317693 https://hal.science/hal-00317693/document https://hal.science/hal-00317693/file/angeo-22-3537-2004.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782338288459186176 |