Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( B y ~ | B z |) 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 |
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Online Access: | https://doi.org/10.5194/angeo-21-539-2003 https://doaj.org/article/687e4a965bdb40e689a450080b68cab0 |
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ftdoajarticles:oai:doaj.org/article:687e4a965bdb40e689a450080b68cab0 2023-05-15T15:17:11+02:00 Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( B y ~ | B z |) IMF orientation P. E. Sandholt J. Moen C. J. Farrugia S. W. H. Cowley M. Lester S. E. Milan C. Valladares W. F. Denig S. Eriksson 2003-02-01T00:00:00Z https://doi.org/10.5194/angeo-21-539-2003 https://doaj.org/article/687e4a965bdb40e689a450080b68cab0 EN eng Copernicus Publications https://www.ann-geophys.net/21/539/2003/angeo-21-539-2003.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-21-539-2003 0992-7689 1432-0576 https://doaj.org/article/687e4a965bdb40e689a450080b68cab0 Annales Geophysicae, Vol 21, Pp 539-558 (2003) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2003 ftdoajarticles https://doi.org/10.5194/angeo-21-539-2003 2022-12-31T04:20:25Z 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, ... Article in Journal/Newspaper Arctic Svalbard Directory of Open Access Journals: DOAJ Articles Arctic Svalbard Annales Geophysicae 21 2 539 558 |
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Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 P. E. Sandholt J. Moen C. J. Farrugia S. W. H. Cowley M. Lester S. E. Milan C. Valladares W. F. Denig S. Eriksson Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( B y ~ | B z |) IMF orientation |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
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, ... |
format |
Article in Journal/Newspaper |
author |
P. E. Sandholt J. Moen C. J. Farrugia S. W. H. Cowley M. Lester S. E. Milan C. Valladares W. F. Denig S. Eriksson |
author_facet |
P. E. Sandholt J. Moen C. J. Farrugia S. W. H. Cowley M. Lester S. E. Milan C. Valladares W. F. Denig S. Eriksson |
author_sort |
P. E. Sandholt |
title |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( B y ~ | B z |) IMF orientation |
title_short |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( B y ~ | B z |) IMF orientation |
title_full |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( B y ~ | B z |) IMF orientation |
title_fullStr |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( B y ~ | B z |) IMF orientation |
title_full_unstemmed |
Multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( B y ~ | B z |) IMF orientation |
title_sort |
multi-site observations of the association between aurora and plasma convection in the cusp/polar cap during a southeastward( b y ~ | b z |) imf orientation |
publisher |
Copernicus Publications |
publishDate |
2003 |
url |
https://doi.org/10.5194/angeo-21-539-2003 https://doaj.org/article/687e4a965bdb40e689a450080b68cab0 |
geographic |
Arctic Svalbard |
geographic_facet |
Arctic Svalbard |
genre |
Arctic Svalbard |
genre_facet |
Arctic Svalbard |
op_source |
Annales Geophysicae, Vol 21, Pp 539-558 (2003) |
op_relation |
https://www.ann-geophys.net/21/539/2003/angeo-21-539-2003.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-21-539-2003 0992-7689 1432-0576 https://doaj.org/article/687e4a965bdb40e689a450080b68cab0 |
op_doi |
https://doi.org/10.5194/angeo-21-539-2003 |
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Annales Geophysicae |
container_volume |
21 |
container_issue |
2 |
container_start_page |
539 |
op_container_end_page |
558 |
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