Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(By ~ |Bz|) IMF orientation
In a case study we demonstrate the spatiotemporal structure of aurora and plasma convection in the cusp/polar cap when the interplanetary magnetic field (IMF) Bz < 0 and By ~ | Bz | (clock angle in GSM Y - Z plane: ~ 135°). This IMF orientation elicited a response different from that correspondin...
Published in: | Annales Geophysicae |
---|---|
Main Authors: | , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2003
|
Subjects: | |
Online Access: | https://doi.org/10.5194/angeo-21-539-2003 https://noa.gwlb.de/receive/cop_mods_00035622 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00035576/angeo-21-539-2003.pdf https://angeo.copernicus.org/articles/21/539/2003/angeo-21-539-2003.pdf |
id |
ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00035622 |
---|---|
record_format |
openpolar |
spelling |
ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00035622 2023-05-15T15:19:13+02:00 Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(By ~ |Bz|) IMF orientation Sandholt, P. E. Moen, J. Farrugia, C. J. Cowley, S. W. H. Lester, M. Milan, S. E. Valladares, C. Denig, W. F. Eriksson, S. 2003-02 electronic https://doi.org/10.5194/angeo-21-539-2003 https://noa.gwlb.de/receive/cop_mods_00035622 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00035576/angeo-21-539-2003.pdf https://angeo.copernicus.org/articles/21/539/2003/angeo-21-539-2003.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-21-539-2003 https://noa.gwlb.de/receive/cop_mods_00035622 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00035576/angeo-21-539-2003.pdf https://angeo.copernicus.org/articles/21/539/2003/angeo-21-539-2003.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2003 ftnonlinearchiv https://doi.org/10.5194/angeo-21-539-2003 2022-02-08T22:44:31Z In a case study we demonstrate the spatiotemporal structure of aurora and plasma convection in the cusp/polar cap when the interplanetary magnetic field (IMF) Bz < 0 and By ~ | Bz | (clock angle in GSM Y - Z plane: ~ 135°). This IMF orientation elicited a response different from that corresponding to strongly northward and southward IMF. Our study of this "intermediate state" is based on a combination of ground observations of optical auroral emissions and ionospheric plasma convection. Utilizing all-sky cameras at NyAlesund, Svalbard and Heiss Island (Russian arctic), we are able to monitor the high-latitude auroral activity within the ~10:00–15:00 MLT sector. Information on plasma convection is obtained from the SuperDARN radars, with emphasis placed on line of sight observations from the radar situated in Hankasalmi, Finland (Cutlass). A central feature of the auroral observations in the cusp/polar cap region is a ~ 30-min long sequence of four brightening events, some of which consists of latitudinally and longitudinally separated forms, which are found to be associated with pulsed ionospheric flows in merging and lobe convection cells. The auroral/convection events may be separated into different forms/cells and phases, reflecting a spatiotem-poral evolution of the reconnection process on the dayside magnetopause. The initial phase consists of a brightening in the postnoon sector (~ 12:00–14:00 MLT) at ~ 73° MLAT, accompanied by a pulse of enhanced westward convection in the postnoon merging cell. Thereafter, the event evolution comprises two phenomena which occur almost simultaneously: (1) westward expansion of the auroral brightening (equatorward boundary intensification) across noon, into the ~ 10:00–12:00 MLT sector, where the plasma convection subsequently turns almost due north, in the convection throat, and where classical poleward moving auroral forms (PMAFs) are observed; and (2) auroral brightening at slightly higher latitudes (~ 75° MLAT) in the postnoon lobe cell, with expansion towards noon, giving rise to a clear cusp bifurcation. The fading phase of PMAFs is accompanied by a "patch" of enhanced (~ 1 km/s) poleward-directed merging cell convection at high latitudes (75–82° MLAT), e.g. more than 500 km poleward of the cusp equatorward boundary. The major aurora/convection events are recurring at ~ 5–10 min intervals. Key words. Magnetospheric physics (auroral phenomena; magnetopause, cusp, and boundary layers; plasma convection) Article in Journal/Newspaper Arctic Svalbard Niedersächsisches Online-Archiv NOA Arctic Svalbard Annales Geophysicae 21 2 539 558 |
institution |
Open Polar |
collection |
Niedersächsisches Online-Archiv NOA |
op_collection_id |
ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
spellingShingle |
article Verlagsveröffentlichung Sandholt, P. E. Moen, J. Farrugia, C. J. Cowley, S. W. H. Lester, M. Milan, S. E. Valladares, C. Denig, W. F. Eriksson, S. Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(By ~ |Bz|) IMF orientation |
topic_facet |
article Verlagsveröffentlichung |
description |
In a case study we demonstrate the spatiotemporal structure of aurora and plasma convection in the cusp/polar cap when the interplanetary magnetic field (IMF) Bz < 0 and By ~ | Bz | (clock angle in GSM Y - Z plane: ~ 135°). This IMF orientation elicited a response different from that corresponding to strongly northward and southward IMF. Our study of this "intermediate state" is based on a combination of ground observations of optical auroral emissions and ionospheric plasma convection. Utilizing all-sky cameras at NyAlesund, Svalbard and Heiss Island (Russian arctic), we are able to monitor the high-latitude auroral activity within the ~10:00–15:00 MLT sector. Information on plasma convection is obtained from the SuperDARN radars, with emphasis placed on line of sight observations from the radar situated in Hankasalmi, Finland (Cutlass). A central feature of the auroral observations in the cusp/polar cap region is a ~ 30-min long sequence of four brightening events, some of which consists of latitudinally and longitudinally separated forms, which are found to be associated with pulsed ionospheric flows in merging and lobe convection cells. The auroral/convection events may be separated into different forms/cells and phases, reflecting a spatiotem-poral evolution of the reconnection process on the dayside magnetopause. The initial phase consists of a brightening in the postnoon sector (~ 12:00–14:00 MLT) at ~ 73° MLAT, accompanied by a pulse of enhanced westward convection in the postnoon merging cell. Thereafter, the event evolution comprises two phenomena which occur almost simultaneously: (1) westward expansion of the auroral brightening (equatorward boundary intensification) across noon, into the ~ 10:00–12:00 MLT sector, where the plasma convection subsequently turns almost due north, in the convection throat, and where classical poleward moving auroral forms (PMAFs) are observed; and (2) auroral brightening at slightly higher latitudes (~ 75° MLAT) in the postnoon lobe cell, with expansion towards noon, giving rise to a clear cusp bifurcation. The fading phase of PMAFs is accompanied by a "patch" of enhanced (~ 1 km/s) poleward-directed merging cell convection at high latitudes (75–82° MLAT), e.g. more than 500 km poleward of the cusp equatorward boundary. The major aurora/convection events are recurring at ~ 5–10 min intervals. Key words. Magnetospheric physics (auroral phenomena; magnetopause, cusp, and boundary layers; plasma convection) |
format |
Article in Journal/Newspaper |
author |
Sandholt, P. E. Moen, J. Farrugia, C. J. Cowley, S. W. H. Lester, M. Milan, S. E. Valladares, C. Denig, W. F. Eriksson, S. |
author_facet |
Sandholt, P. E. Moen, J. Farrugia, C. J. Cowley, S. W. H. Lester, M. Milan, S. E. Valladares, C. Denig, W. F. Eriksson, S. |
author_sort |
Sandholt, P. E. |
title |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(By ~ |Bz|) IMF orientation |
title_short |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(By ~ |Bz|) IMF orientation |
title_full |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(By ~ |Bz|) IMF orientation |
title_fullStr |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(By ~ |Bz|) IMF orientation |
title_full_unstemmed |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(By ~ |Bz|) IMF orientation |
title_sort |
multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward(by ~ |bz|) imf orientation |
publisher |
Copernicus Publications |
publishDate |
2003 |
url |
https://doi.org/10.5194/angeo-21-539-2003 https://noa.gwlb.de/receive/cop_mods_00035622 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00035576/angeo-21-539-2003.pdf https://angeo.copernicus.org/articles/21/539/2003/angeo-21-539-2003.pdf |
geographic |
Arctic Svalbard |
geographic_facet |
Arctic Svalbard |
genre |
Arctic Svalbard |
genre_facet |
Arctic Svalbard |
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-21-539-2003 https://noa.gwlb.de/receive/cop_mods_00035622 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00035576/angeo-21-539-2003.pdf https://angeo.copernicus.org/articles/21/539/2003/angeo-21-539-2003.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/angeo-21-539-2003 |
container_title |
Annales Geophysicae |
container_volume |
21 |
container_issue |
2 |
container_start_page |
539 |
op_container_end_page |
558 |
_version_ |
1766349399509696512 |