Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images
International audience We demonstrate that high-resolution 557.7-nm all-sky images are useful tools for investigating the spatial and temporal evolution of merging on the dayside magnetopause. Analysis of ground and satellite measurements leads us to conclude that high-latitude merging events can oc...
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ftunivnantes:oai:HAL:hal-00317591v1 2023-05-15T17:48:28+02:00 Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images Maynard, N. C. Moen, J. Burke, W. J. Lester, M. Ober, D. M. Scudder, J. D. Siebert, K. D. Weimer, D. R. Russell, C. T. Balogh, A. ATK Mission Research University of Oslo (UiO) Air Force Research Laboratory (AFRL) United States Air Force (USAF) University of Leicester Department of Physics and Astronomy Iowa City University of Iowa Iowa City University of California Los Angeles (UCLA) University of California (UC) Imperial College London 2004-09-07 https://hal.archives-ouvertes.fr/hal-00317591 https://hal.archives-ouvertes.fr/hal-00317591/document https://hal.archives-ouvertes.fr/hal-00317591/file/angeo-22-2917-2004.pdf en eng HAL CCSD European Geosciences Union hal-00317591 https://hal.archives-ouvertes.fr/hal-00317591 https://hal.archives-ouvertes.fr/hal-00317591/document https://hal.archives-ouvertes.fr/hal-00317591/file/angeo-22-2917-2004.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.archives-ouvertes.fr/hal-00317591 Annales Geophysicae, 2004, 22 (8), pp.2917-2942 [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 ftunivnantes 2022-11-30T00:48:43Z International audience We demonstrate that high-resolution 557.7-nm all-sky images are useful tools for investigating the spatial and temporal evolution of merging on the dayside magnetopause. Analysis of ground and satellite measurements leads us to conclude that high-latitude merging events can occur at multiple sites simultaneously and vary asynchronously on time scales of 30s to 3min. Variations of 557.7nm emissions were observed at a 10s cadence at Ny-Ålesund on 19 December 2001, while significant changes in the IMF clock angle were reaching the magnetopause. The optical patterns are consistent with a scenario in which merging occurs around the rim of the high-latitude cusp at positions dictated by the IMF clock angle. Electrons energized at merging sites represent plausible sources for 557.7nm emissions in the cusp. Polar observations at the magnetopause have directly linked enhanced fluxes of ?0.5keV electrons with merging. Spectra of electrons responsible for some of the emissions, measured during a DMSP F15 overflight, exhibit "inverted-V" features, indicating further acceleration above the ionosphere. SuperDARN spectral width boundaries, characteristic of open-closed field line transitions, are located at the equatorward edge of the 557.7nm emissions. Optical data suggest that with IMF B Y >0, the Northern Hemisphere cusp divides into three source regions. When the IMF clock angle was ~150° structured 557.7-nm emissions came from east of the 13:00 MLT meridian. At larger clock angles the emissions appeared between 12:00 and 13:00 MLT. No significant 557.7-nm emissions were detected in the prenoon MLT sector. MHD simulations corroborate our scenario, showing that with the observed large dipole-tilt and IMF clock angles, merging sites develop near the front and eastern portions of the high-altitude cusp rim in the Northern Hemisphere and near the western part of the cusp rim in the Southern Hemisphere. Article in Journal/Newspaper Ny Ålesund Ny-Ålesund Université de Nantes: HAL-UNIV-NANTES Ny-Ålesund |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
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 Maynard, N. C. Moen, J. Burke, W. J. Lester, M. Ober, D. M. Scudder, J. D. Siebert, K. D. Weimer, D. R. Russell, C. T. Balogh, A. Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience We demonstrate that high-resolution 557.7-nm all-sky images are useful tools for investigating the spatial and temporal evolution of merging on the dayside magnetopause. Analysis of ground and satellite measurements leads us to conclude that high-latitude merging events can occur at multiple sites simultaneously and vary asynchronously on time scales of 30s to 3min. Variations of 557.7nm emissions were observed at a 10s cadence at Ny-Ålesund on 19 December 2001, while significant changes in the IMF clock angle were reaching the magnetopause. The optical patterns are consistent with a scenario in which merging occurs around the rim of the high-latitude cusp at positions dictated by the IMF clock angle. Electrons energized at merging sites represent plausible sources for 557.7nm emissions in the cusp. Polar observations at the magnetopause have directly linked enhanced fluxes of ?0.5keV electrons with merging. Spectra of electrons responsible for some of the emissions, measured during a DMSP F15 overflight, exhibit "inverted-V" features, indicating further acceleration above the ionosphere. SuperDARN spectral width boundaries, characteristic of open-closed field line transitions, are located at the equatorward edge of the 557.7nm emissions. Optical data suggest that with IMF B Y >0, the Northern Hemisphere cusp divides into three source regions. When the IMF clock angle was ~150° structured 557.7-nm emissions came from east of the 13:00 MLT meridian. At larger clock angles the emissions appeared between 12:00 and 13:00 MLT. No significant 557.7-nm emissions were detected in the prenoon MLT sector. MHD simulations corroborate our scenario, showing that with the observed large dipole-tilt and IMF clock angles, merging sites develop near the front and eastern portions of the high-altitude cusp rim in the Northern Hemisphere and near the western part of the cusp rim in the Southern Hemisphere. |
author2 |
ATK Mission Research University of Oslo (UiO) Air Force Research Laboratory (AFRL) United States Air Force (USAF) University of Leicester Department of Physics and Astronomy Iowa City University of Iowa Iowa City University of California Los Angeles (UCLA) University of California (UC) Imperial College London |
format |
Article in Journal/Newspaper |
author |
Maynard, N. C. Moen, J. Burke, W. J. Lester, M. Ober, D. M. Scudder, J. D. Siebert, K. D. Weimer, D. R. Russell, C. T. Balogh, A. |
author_facet |
Maynard, N. C. Moen, J. Burke, W. J. Lester, M. Ober, D. M. Scudder, J. D. Siebert, K. D. Weimer, D. R. Russell, C. T. Balogh, A. |
author_sort |
Maynard, N. C. |
title |
Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images |
title_short |
Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images |
title_full |
Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images |
title_fullStr |
Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images |
title_full_unstemmed |
Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images |
title_sort |
temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images |
publisher |
HAL CCSD |
publishDate |
2004 |
url |
https://hal.archives-ouvertes.fr/hal-00317591 https://hal.archives-ouvertes.fr/hal-00317591/document https://hal.archives-ouvertes.fr/hal-00317591/file/angeo-22-2917-2004.pdf |
geographic |
Ny-Ålesund |
geographic_facet |
Ny-Ålesund |
genre |
Ny Ålesund Ny-Ålesund |
genre_facet |
Ny Ålesund Ny-Ålesund |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.archives-ouvertes.fr/hal-00317591 Annales Geophysicae, 2004, 22 (8), pp.2917-2942 |
op_relation |
hal-00317591 https://hal.archives-ouvertes.fr/hal-00317591 https://hal.archives-ouvertes.fr/hal-00317591/document https://hal.archives-ouvertes.fr/hal-00317591/file/angeo-22-2917-2004.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1766154555124350976 |