Poleward moving auroral forms (PMAFs) revisited: responses of aurorae, plasma convection and Birkeland currents in the pre- and postnoon sectors under positive and negative IMF B y conditions
Using five case studies, we investigate the dynamical evolution of dayside auroral precipitation in relation to plasma convection, classifying it by the IMF B y component and position with respect to noon. Auroral observations were made by meridian scanning photometers (MSPs) and an all-sky camera (...
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Language: | English |
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Copernicus Publications
2007
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Online Access: | https://doi.org/10.5194/angeo-25-1629-2007 https://doaj.org/article/add97b4adcca44d78ef5ad3937f77be0 |
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ftdoajarticles:oai:doaj.org/article:add97b4adcca44d78ef5ad3937f77be0 2023-05-15T17:48:28+02:00 Poleward moving auroral forms (PMAFs) revisited: responses of aurorae, plasma convection and Birkeland currents in the pre- and postnoon sectors under positive and negative IMF B y conditions P. E. Sandholt C. J. Farrugia 2007-07-01T00:00:00Z https://doi.org/10.5194/angeo-25-1629-2007 https://doaj.org/article/add97b4adcca44d78ef5ad3937f77be0 EN eng Copernicus Publications https://www.ann-geophys.net/25/1629/2007/angeo-25-1629-2007.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-25-1629-2007 0992-7689 1432-0576 https://doaj.org/article/add97b4adcca44d78ef5ad3937f77be0 Annales Geophysicae, Vol 25, Pp 1629-1652 (2007) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2007 ftdoajarticles https://doi.org/10.5194/angeo-25-1629-2007 2022-12-30T22:43:48Z Using five case studies, we investigate the dynamical evolution of dayside auroral precipitation in relation to plasma convection, classifying it by the IMF B y component and position with respect to noon. Auroral observations were made by meridian scanning photometers (MSPs) and an all-sky camera (ASC) in Ny Ålesund, Svalbard at 76° MLAT, while the spatial structure of the ionospheric plasma convection is inferred from SuperDARN radars and ion drift observations from spacecraft in polar orbit. The IMF configuration of major interest here is one pointing southward and with a dominant east-west component. Our emphasis is on the auroral phenomenon of PMAFs (poleward moving auroral forms), which are ionospheric signatures of pulsed reconnection at the magnetopause. We distinguish between PMAFs/prenoon and PMAFs/postnoon. These two activities are found to be separated by an auroral form around noon with attenuated emission at 630.0 nm. We document for the first time that this "midday gap aurora" appears in the form of a midday auroral brightening sequence (MABS). We study the PMAF activity consisting of an initial brightening phase and the later stages of PMAF evolution in relation to plasma convection cells, flow vorticity, and precipitation boundaries in the prenoon and postnoon sectors for both B y polarities. Flow channels (PIFs) associated with PMAFs are strengthened by polarization effects at auroral boundaries. Addressing the implications of our proposed, extended perspective on dayside auroral morphology under southeast/west IMF for M-I coupling associated with pulsed magnetopause reconnection (FTEs), we draw inferences on the MLT-dependent geoeffectiveness (Birkeland current/auroral intensity) of magnetopause FTEs (subsolar region versus flanks). Article in Journal/Newspaper Ny Ålesund Ny-Ålesund Svalbard Directory of Open Access Journals: DOAJ Articles Birkeland ENVELOPE(16.587,16.587,68.594,68.594) Ny-Ålesund Svalbard Annales Geophysicae 25 7 1629 1652 |
institution |
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 C. J. Farrugia Poleward moving auroral forms (PMAFs) revisited: responses of aurorae, plasma convection and Birkeland currents in the pre- and postnoon sectors under positive and negative IMF B y conditions |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
Using five case studies, we investigate the dynamical evolution of dayside auroral precipitation in relation to plasma convection, classifying it by the IMF B y component and position with respect to noon. Auroral observations were made by meridian scanning photometers (MSPs) and an all-sky camera (ASC) in Ny Ålesund, Svalbard at 76° MLAT, while the spatial structure of the ionospheric plasma convection is inferred from SuperDARN radars and ion drift observations from spacecraft in polar orbit. The IMF configuration of major interest here is one pointing southward and with a dominant east-west component. Our emphasis is on the auroral phenomenon of PMAFs (poleward moving auroral forms), which are ionospheric signatures of pulsed reconnection at the magnetopause. We distinguish between PMAFs/prenoon and PMAFs/postnoon. These two activities are found to be separated by an auroral form around noon with attenuated emission at 630.0 nm. We document for the first time that this "midday gap aurora" appears in the form of a midday auroral brightening sequence (MABS). We study the PMAF activity consisting of an initial brightening phase and the later stages of PMAF evolution in relation to plasma convection cells, flow vorticity, and precipitation boundaries in the prenoon and postnoon sectors for both B y polarities. Flow channels (PIFs) associated with PMAFs are strengthened by polarization effects at auroral boundaries. Addressing the implications of our proposed, extended perspective on dayside auroral morphology under southeast/west IMF for M-I coupling associated with pulsed magnetopause reconnection (FTEs), we draw inferences on the MLT-dependent geoeffectiveness (Birkeland current/auroral intensity) of magnetopause FTEs (subsolar region versus flanks). |
format |
Article in Journal/Newspaper |
author |
P. E. Sandholt C. J. Farrugia |
author_facet |
P. E. Sandholt C. J. Farrugia |
author_sort |
P. E. Sandholt |
title |
Poleward moving auroral forms (PMAFs) revisited: responses of aurorae, plasma convection and Birkeland currents in the pre- and postnoon sectors under positive and negative IMF B y conditions |
title_short |
Poleward moving auroral forms (PMAFs) revisited: responses of aurorae, plasma convection and Birkeland currents in the pre- and postnoon sectors under positive and negative IMF B y conditions |
title_full |
Poleward moving auroral forms (PMAFs) revisited: responses of aurorae, plasma convection and Birkeland currents in the pre- and postnoon sectors under positive and negative IMF B y conditions |
title_fullStr |
Poleward moving auroral forms (PMAFs) revisited: responses of aurorae, plasma convection and Birkeland currents in the pre- and postnoon sectors under positive and negative IMF B y conditions |
title_full_unstemmed |
Poleward moving auroral forms (PMAFs) revisited: responses of aurorae, plasma convection and Birkeland currents in the pre- and postnoon sectors under positive and negative IMF B y conditions |
title_sort |
poleward moving auroral forms (pmafs) revisited: responses of aurorae, plasma convection and birkeland currents in the pre- and postnoon sectors under positive and negative imf b y conditions |
publisher |
Copernicus Publications |
publishDate |
2007 |
url |
https://doi.org/10.5194/angeo-25-1629-2007 https://doaj.org/article/add97b4adcca44d78ef5ad3937f77be0 |
long_lat |
ENVELOPE(16.587,16.587,68.594,68.594) |
geographic |
Birkeland Ny-Ålesund Svalbard |
geographic_facet |
Birkeland Ny-Ålesund Svalbard |
genre |
Ny Ålesund Ny-Ålesund Svalbard |
genre_facet |
Ny Ålesund Ny-Ålesund Svalbard |
op_source |
Annales Geophysicae, Vol 25, Pp 1629-1652 (2007) |
op_relation |
https://www.ann-geophys.net/25/1629/2007/angeo-25-1629-2007.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-25-1629-2007 0992-7689 1432-0576 https://doaj.org/article/add97b4adcca44d78ef5ad3937f77be0 |
op_doi |
https://doi.org/10.5194/angeo-25-1629-2007 |
container_title |
Annales Geophysicae |
container_volume |
25 |
container_issue |
7 |
container_start_page |
1629 |
op_container_end_page |
1652 |
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1766154547059752960 |