Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate
Using data from the EISCAT (European Incoherent Scatter) VHF and CUTLASS (Co-operative UK Twin-Located Auroral Sounding System) HF radars, we study the formation of ionospheric polar cap patches and their relationship to the magnetopause reconnection pulses identified in the companion paper by Lockw...
Published in: | Annales Geophysicae |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Copernicus Publications
2005
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00033664 2023-05-15T16:04:37+02:00 Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate Lockwood, M. Davies, J. A. Moen, J. van Eyken, A. P. Oksavik, K. McCrea, I. W. Lester, M. 2005-12 electronic https://doi.org/10.5194/angeo-23-3513-2005 https://noa.gwlb.de/receive/cop_mods_00033664 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00033618/angeo-23-3513-2005.pdf https://angeo.copernicus.org/articles/23/3513/2005/angeo-23-3513-2005.pdf eng eng Copernicus Publications Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.5194/angeo-23-3513-2005 https://noa.gwlb.de/receive/cop_mods_00033664 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00033618/angeo-23-3513-2005.pdf https://angeo.copernicus.org/articles/23/3513/2005/angeo-23-3513-2005.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2005 ftnonlinearchiv https://doi.org/10.5194/angeo-23-3513-2005 2022-02-08T22:45:39Z Using data from the EISCAT (European Incoherent Scatter) VHF and CUTLASS (Co-operative UK Twin-Located Auroral Sounding System) HF radars, we study the formation of ionospheric polar cap patches and their relationship to the magnetopause reconnection pulses identified in the companion paper by Lockwood et al. (2005). It is shown that the poleward-moving, high-concentration plasma patches observed in the ionosphere by EISCAT on 23 November 1999, as reported by Davies et al. (2002), were often associated with corresponding reconnection rate pulses. However, not all such pulses generated a patch and only within a limited MLT range (11:00-12:00 MLT) did a patch result from a reconnection pulse. Three proposed mechanisms for the production of patches, and of the concentration minima that separate them, are analysed and evaluated: (1) concentration enhancement within the patches by cusp/cleft precipitation; (2) plasma depletion in the minima between the patches by fast plasma flows; and (3) intermittent injection of photoionisation-enhanced plasma into the polar cap. We devise a test to distinguish between the effects of these mechanisms. Some of the events repeat too frequently to apply the test. Others have sufficiently long repeat periods and mechanism (3) is shown to be the only explanation of three of the longer-lived patches seen on this day. However, effect (2) also appears to contribute to some events. We conclude that plasma concentration gradients on the edges of the larger patches arise mainly from local time variations in the subauroral plasma, via the mechanism proposed by Lockwood et al. (2000). Article in Journal/Newspaper EISCAT Niedersächsisches Online-Archiv NOA Lockwood ENVELOPE(167.400,167.400,-84.150,-84.150) Annales Geophysicae 23 11 3513 3532 |
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Open Polar |
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Niedersächsisches Online-Archiv NOA |
op_collection_id |
ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Lockwood, M. Davies, J. A. Moen, J. van Eyken, A. P. Oksavik, K. McCrea, I. W. Lester, M. Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate |
topic_facet |
article Verlagsveröffentlichung |
description |
Using data from the EISCAT (European Incoherent Scatter) VHF and CUTLASS (Co-operative UK Twin-Located Auroral Sounding System) HF radars, we study the formation of ionospheric polar cap patches and their relationship to the magnetopause reconnection pulses identified in the companion paper by Lockwood et al. (2005). It is shown that the poleward-moving, high-concentration plasma patches observed in the ionosphere by EISCAT on 23 November 1999, as reported by Davies et al. (2002), were often associated with corresponding reconnection rate pulses. However, not all such pulses generated a patch and only within a limited MLT range (11:00-12:00 MLT) did a patch result from a reconnection pulse. Three proposed mechanisms for the production of patches, and of the concentration minima that separate them, are analysed and evaluated: (1) concentration enhancement within the patches by cusp/cleft precipitation; (2) plasma depletion in the minima between the patches by fast plasma flows; and (3) intermittent injection of photoionisation-enhanced plasma into the polar cap. We devise a test to distinguish between the effects of these mechanisms. Some of the events repeat too frequently to apply the test. Others have sufficiently long repeat periods and mechanism (3) is shown to be the only explanation of three of the longer-lived patches seen on this day. However, effect (2) also appears to contribute to some events. We conclude that plasma concentration gradients on the edges of the larger patches arise mainly from local time variations in the subauroral plasma, via the mechanism proposed by Lockwood et al. (2000). |
format |
Article in Journal/Newspaper |
author |
Lockwood, M. Davies, J. A. Moen, J. van Eyken, A. P. Oksavik, K. McCrea, I. W. Lester, M. |
author_facet |
Lockwood, M. Davies, J. A. Moen, J. van Eyken, A. P. Oksavik, K. McCrea, I. W. Lester, M. |
author_sort |
Lockwood, M. |
title |
Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate |
title_short |
Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate |
title_full |
Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate |
title_fullStr |
Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate |
title_full_unstemmed |
Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate |
title_sort |
motion of the dayside polar cap boundary during substorm cycles: ii. generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate |
publisher |
Copernicus Publications |
publishDate |
2005 |
url |
https://doi.org/10.5194/angeo-23-3513-2005 https://noa.gwlb.de/receive/cop_mods_00033664 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00033618/angeo-23-3513-2005.pdf https://angeo.copernicus.org/articles/23/3513/2005/angeo-23-3513-2005.pdf |
long_lat |
ENVELOPE(167.400,167.400,-84.150,-84.150) |
geographic |
Lockwood |
geographic_facet |
Lockwood |
genre |
EISCAT |
genre_facet |
EISCAT |
op_relation |
Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.5194/angeo-23-3513-2005 https://noa.gwlb.de/receive/cop_mods_00033664 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00033618/angeo-23-3513-2005.pdf https://angeo.copernicus.org/articles/23/3513/2005/angeo-23-3513-2005.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/angeo-23-3513-2005 |
container_title |
Annales Geophysicae |
container_volume |
23 |
container_issue |
11 |
container_start_page |
3513 |
op_container_end_page |
3532 |
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1766400222260363264 |