The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF
International audience We document the detailed dynamics of the dayside aurora in the \sim1200-1600 MLT sector in response to a sharp southward turning of the interplanetary magnetic field (IMF) under negative IMF B y conditions. Features not documented in previous work are elucidated by using two m...
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ftinsu:oai:HAL:hal-00316661v1 2023-11-12T04:23:34+01:00 The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF Sandholt, P. E. Farrugia, C. J. Lybekk, B. Department of Physics Okayama University Institute for Study of Earth, Oceans and Space University of New Hampshire (UNH) 1999 https://hal.science/hal-00316661 https://hal.science/hal-00316661/document https://hal.science/hal-00316661/file/angeo-17-1155-1999.pdf en eng HAL CCSD European Geosciences Union hal-00316661 https://hal.science/hal-00316661 https://hal.science/hal-00316661/document https://hal.science/hal-00316661/file/angeo-17-1155-1999.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00316661 Annales Geophysicae, 1999, 17 (9), pp.1155-1165 [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 1999 ftinsu 2023-10-25T16:25:32Z International audience We document the detailed dynamics of the dayside aurora in the \sim1200-1600 MLT sector in response to a sharp southward turning of the interplanetary magnetic field (IMF) under negative IMF B y conditions. Features not documented in previous work are elucidated by using two meridan scanning photometers (separated by 2 h) and an all-sky auroral imager in Ny Ålesund, Svalbard (75.5 ° MLAT) in combination with magnetograms from stations on Svalbard, covering the latitude range 71 ° 75 ° MLAT. The initial auroral response may be divided into three phases consisting of: (1) intensification of both the red (630.0 nm) and green (557.7 nm) line emissions in the cusp aurora near 1200 MLT and ~100 km equatorward shift of its equatorward boundary, at ~75 ° MLAT, (2) eastward and poleward expansions of the cusp aurora, reaching the 1430 MLT meridian after 5-6 min, and (3) east-west expansion of the higher-latitude aurora (at ~77 ° 78 ° MLAT) in the postnoon sector. The associated magnetic disturbance is characterized by an initial positive deflection of the X-component at stations located 100-400 km south of the aurora, corresponding to enhanced Sunward return flow associated with the merging convection cell in the post-noon sector. The sequence of partly overlapping poleward moving auroral forms (PMAFs) during the first 15 min, accompanied by corresponding pulsations in the convection current, was followed by a strong westward contraction of the cusp aurora when the ground magnetograms indicated a temporary return to the pre-onset level. These observations are discussed in relation to the Cowley-Lockwood model of ionospheric response to pulsed magnetopause reconnection. Article in Journal/Newspaper Ny Ålesund Ny-Ålesund Svalbard Institut national des sciences de l'Univers: HAL-INSU Cowley ENVELOPE(-134.909,-134.909,60.518,60.518) Lockwood ENVELOPE(167.400,167.400,-84.150,-84.150) 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. Lybekk, B. The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience We document the detailed dynamics of the dayside aurora in the \sim1200-1600 MLT sector in response to a sharp southward turning of the interplanetary magnetic field (IMF) under negative IMF B y conditions. Features not documented in previous work are elucidated by using two meridan scanning photometers (separated by 2 h) and an all-sky auroral imager in Ny Ålesund, Svalbard (75.5 ° MLAT) in combination with magnetograms from stations on Svalbard, covering the latitude range 71 ° 75 ° MLAT. The initial auroral response may be divided into three phases consisting of: (1) intensification of both the red (630.0 nm) and green (557.7 nm) line emissions in the cusp aurora near 1200 MLT and ~100 km equatorward shift of its equatorward boundary, at ~75 ° MLAT, (2) eastward and poleward expansions of the cusp aurora, reaching the 1430 MLT meridian after 5-6 min, and (3) east-west expansion of the higher-latitude aurora (at ~77 ° 78 ° MLAT) in the postnoon sector. The associated magnetic disturbance is characterized by an initial positive deflection of the X-component at stations located 100-400 km south of the aurora, corresponding to enhanced Sunward return flow associated with the merging convection cell in the post-noon sector. The sequence of partly overlapping poleward moving auroral forms (PMAFs) during the first 15 min, accompanied by corresponding pulsations in the convection current, was followed by a strong westward contraction of the cusp aurora when the ground magnetograms indicated a temporary return to the pre-onset level. These observations are discussed in relation to the Cowley-Lockwood model of ionospheric response to pulsed magnetopause reconnection. |
author2 |
Department of Physics Okayama University Institute for Study of Earth, Oceans and Space University of New Hampshire (UNH) |
format |
Article in Journal/Newspaper |
author |
Sandholt, P. E. Farrugia, C. J. Lybekk, B. |
author_facet |
Sandholt, P. E. Farrugia, C. J. Lybekk, B. |
author_sort |
Sandholt, P. E. |
title |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_short |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_full |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_fullStr |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_full_unstemmed |
The dynamic cusp aurora on 30 November 1997: response to southward turning of the IMF |
title_sort |
dynamic cusp aurora on 30 november 1997: response to southward turning of the imf |
publisher |
HAL CCSD |
publishDate |
1999 |
url |
https://hal.science/hal-00316661 https://hal.science/hal-00316661/document https://hal.science/hal-00316661/file/angeo-17-1155-1999.pdf |
long_lat |
ENVELOPE(-134.909,-134.909,60.518,60.518) ENVELOPE(167.400,167.400,-84.150,-84.150) |
geographic |
Cowley Lockwood Ny-Ålesund Svalbard |
geographic_facet |
Cowley Lockwood 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-00316661 Annales Geophysicae, 1999, 17 (9), pp.1155-1165 |
op_relation |
hal-00316661 https://hal.science/hal-00316661 https://hal.science/hal-00316661/document https://hal.science/hal-00316661/file/angeo-17-1155-1999.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782338284165267456 |