Occurrence statistics of magnetic impulsive events
International audience In this study, we perform a statistical investigation of magnetic impulse events identified in the Greenland magnetometer stations through the years 1995?2001. We focus on occurrence statistics that can be determined reliably with an automatic event identification procedure. D...
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ftccsdartic:oai:HAL:hal-00317240v1 2023-11-12T04:17:54+01:00 Occurrence statistics of magnetic impulsive events Moretto, T. Sibeck, D. G. Watermann, J. F. GSFC Laboratory for Extraterrestrial Physics NASA Goddard Space Flight Center (GSFC) Danish Meteorological Institute (DMI) 2004-01-01 https://hal.science/hal-00317240 https://hal.science/hal-00317240/document https://hal.science/hal-00317240/file/angeo-22-585-2004.pdf en eng HAL CCSD European Geosciences Union hal-00317240 https://hal.science/hal-00317240 https://hal.science/hal-00317240/document https://hal.science/hal-00317240/file/angeo-22-585-2004.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317240 Annales Geophysicae, 2004, 22 (2), pp.585-602 [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 ftccsdartic 2023-10-21T23:07:35Z International audience In this study, we perform a statistical investigation of magnetic impulse events identified in the Greenland magnetometer stations through the years 1995?2001. We focus on occurrence statistics that can be determined reliably with an automatic event identification procedure. Durin the first two years we observed almost 40% more events than in the following years. Season is not a significant factor in event occurrence. Event occurrence peaks near 12:00 UT, corresponding to approximately 10:00 magnetic local time (MLT) at the west coast of Greenland. More events occur prior to local noon than after. Event days are not distributed evenly. Large amplitude events, particularly, tend to appear on consecutive days. Events are observed at lower latitudes at earlier local times in a way consistent with the projection of the outer magnetospheric boundary into the ionosphere. Event latitude depends on dipole tilt angle in a manner similar to that reported for the cusp. Events occur during intervals of enhanced K p . The main reason for this is that the events themselves contribute to the K p index. Events exhibit a preference for high solar wind velocity. In particular, the large amplitude events occur during high-speed streams. A slight preference for lower density and more radial interplanetary magnetic fields, as compared to the nominal solar wind distribution, is also observed. However, both the nominal solar wind and event distribution exhibit large differences from year to year, indicating that events occur under a broad range of conditions. Key words. Ionosphere (ionospheric disturbances) Magnetospheric physics (magnetosphere-ionosphere interactions; solar wind-magnetosphere interactions) Article in Journal/Newspaper Greenland Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) 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 Moretto, T. Sibeck, D. G. Watermann, J. F. Occurrence statistics of magnetic impulsive events |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience In this study, we perform a statistical investigation of magnetic impulse events identified in the Greenland magnetometer stations through the years 1995?2001. We focus on occurrence statistics that can be determined reliably with an automatic event identification procedure. Durin the first two years we observed almost 40% more events than in the following years. Season is not a significant factor in event occurrence. Event occurrence peaks near 12:00 UT, corresponding to approximately 10:00 magnetic local time (MLT) at the west coast of Greenland. More events occur prior to local noon than after. Event days are not distributed evenly. Large amplitude events, particularly, tend to appear on consecutive days. Events are observed at lower latitudes at earlier local times in a way consistent with the projection of the outer magnetospheric boundary into the ionosphere. Event latitude depends on dipole tilt angle in a manner similar to that reported for the cusp. Events occur during intervals of enhanced K p . The main reason for this is that the events themselves contribute to the K p index. Events exhibit a preference for high solar wind velocity. In particular, the large amplitude events occur during high-speed streams. A slight preference for lower density and more radial interplanetary magnetic fields, as compared to the nominal solar wind distribution, is also observed. However, both the nominal solar wind and event distribution exhibit large differences from year to year, indicating that events occur under a broad range of conditions. Key words. Ionosphere (ionospheric disturbances) Magnetospheric physics (magnetosphere-ionosphere interactions; solar wind-magnetosphere interactions) |
author2 |
GSFC Laboratory for Extraterrestrial Physics NASA Goddard Space Flight Center (GSFC) Danish Meteorological Institute (DMI) |
format |
Article in Journal/Newspaper |
author |
Moretto, T. Sibeck, D. G. Watermann, J. F. |
author_facet |
Moretto, T. Sibeck, D. G. Watermann, J. F. |
author_sort |
Moretto, T. |
title |
Occurrence statistics of magnetic impulsive events |
title_short |
Occurrence statistics of magnetic impulsive events |
title_full |
Occurrence statistics of magnetic impulsive events |
title_fullStr |
Occurrence statistics of magnetic impulsive events |
title_full_unstemmed |
Occurrence statistics of magnetic impulsive events |
title_sort |
occurrence statistics of magnetic impulsive events |
publisher |
HAL CCSD |
publishDate |
2004 |
url |
https://hal.science/hal-00317240 https://hal.science/hal-00317240/document https://hal.science/hal-00317240/file/angeo-22-585-2004.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317240 Annales Geophysicae, 2004, 22 (2), pp.585-602 |
op_relation |
hal-00317240 https://hal.science/hal-00317240 https://hal.science/hal-00317240/document https://hal.science/hal-00317240/file/angeo-22-585-2004.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782334655871057920 |