Occurrence statistics of magnetic impulsive events
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 year...
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ftcopernicus:oai:publications.copernicus.org:angeo35113 2023-05-15T16:28:19+02:00 Occurrence statistics of magnetic impulsive events Moretto, T. Sibeck, D. G. Watermann, J. F. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-22-585-2004 https://angeo.copernicus.org/articles/22/585/2004/ eng eng doi:10.5194/angeo-22-585-2004 https://angeo.copernicus.org/articles/22/585/2004/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-22-585-2004 2020-07-20T16:27:38Z 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 12:00UT, 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) Text Greenland Copernicus Publications: E-Journals Greenland Annales Geophysicae 22 2 585 602 |
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Open Polar |
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Copernicus Publications: E-Journals |
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English |
description |
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 12:00UT, 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) |
format |
Text |
author |
Moretto, T. Sibeck, D. G. Watermann, J. F. |
spellingShingle |
Moretto, T. Sibeck, D. G. Watermann, J. F. Occurrence statistics of magnetic impulsive events |
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 |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-22-585-2004 https://angeo.copernicus.org/articles/22/585/2004/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-22-585-2004 https://angeo.copernicus.org/articles/22/585/2004/ |
op_doi |
https://doi.org/10.5194/angeo-22-585-2004 |
container_title |
Annales Geophysicae |
container_volume |
22 |
container_issue |
2 |
container_start_page |
585 |
op_container_end_page |
602 |
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1766017967927066624 |