Dayside aurorae and polar arcs under south-east IMF orientation
We document a characteristic spatial and temporal structure of the aurora in the postnoon sector present during a 10-h-long interval of very steady southeast IMF orientation (clock angle=135°) ending in a sharp south-to-north transition. Focus is placed on the detailed morphology of auroral forms/ac...
Published in: | Annales Geophysicae |
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Online Access: | https://doi.org/10.5194/angeo-24-3421-2006 https://angeo.copernicus.org/articles/24/3421/2006/ |
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ftcopernicus:oai:publications.copernicus.org:angeo36068 2023-05-15T16:29:42+02:00 Dayside aurorae and polar arcs under south-east IMF orientation Sandholt, P. E. Dyrland, M. Farrugia, C. J. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-24-3421-2006 https://angeo.copernicus.org/articles/24/3421/2006/ eng eng doi:10.5194/angeo-24-3421-2006 https://angeo.copernicus.org/articles/24/3421/2006/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-24-3421-2006 2020-07-20T16:27:10Z We document a characteristic spatial and temporal structure of the aurora in the postnoon sector present during a 10-h-long interval of very steady southeast IMF orientation (clock angle=135°) ending in a sharp south-to-north transition. Focus is placed on the detailed morphology of auroral forms/activities corresponding to merging and lobe convection cells obtained from SuperDARN convection data and Greenland magnetograms. The ground optical instruments at Ny Ålesund, Svalbard (76° MLAT) recorded different auroral forms/activities as the station moved to higher magnetic local times (MLTs) in the 13:00–17:00 MLT sector. Whereas the 13:00–15:00 MLT sector is characterized by classical poleward moving auroral forms (PMAFs) associated with merging cell transients, the aurora in the 15:00–17:00 MLT sector shows instead a characteristic latitudinal bifurcation consisting of standard oval forms and polar arcs, and a corresponding composite pattern of merging and lobe convection cells. The merging and lobe cells respond to the southward and northward IMF transitions by activation/fading and fading/activation, respectively. A sequence of brightening events is characterized by successive activations progressing in latitude from the merging cell regime to the lobe cell regime. Emphasis is placed on the association between polar arc brightenings and the activation of the channel of enhanced sunward flow in the lobe cell. The observations are discussed in relation to recent work on solar wind-magnetosphere-ionosphere interconnection topology. Text Greenland Ny Ålesund Ny-Ålesund Svalbard Copernicus Publications: E-Journals Greenland Ny-Ålesund Svalbard Annales Geophysicae 24 12 3421 3432 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
We document a characteristic spatial and temporal structure of the aurora in the postnoon sector present during a 10-h-long interval of very steady southeast IMF orientation (clock angle=135°) ending in a sharp south-to-north transition. Focus is placed on the detailed morphology of auroral forms/activities corresponding to merging and lobe convection cells obtained from SuperDARN convection data and Greenland magnetograms. The ground optical instruments at Ny Ålesund, Svalbard (76° MLAT) recorded different auroral forms/activities as the station moved to higher magnetic local times (MLTs) in the 13:00–17:00 MLT sector. Whereas the 13:00–15:00 MLT sector is characterized by classical poleward moving auroral forms (PMAFs) associated with merging cell transients, the aurora in the 15:00–17:00 MLT sector shows instead a characteristic latitudinal bifurcation consisting of standard oval forms and polar arcs, and a corresponding composite pattern of merging and lobe convection cells. The merging and lobe cells respond to the southward and northward IMF transitions by activation/fading and fading/activation, respectively. A sequence of brightening events is characterized by successive activations progressing in latitude from the merging cell regime to the lobe cell regime. Emphasis is placed on the association between polar arc brightenings and the activation of the channel of enhanced sunward flow in the lobe cell. The observations are discussed in relation to recent work on solar wind-magnetosphere-ionosphere interconnection topology. |
format |
Text |
author |
Sandholt, P. E. Dyrland, M. Farrugia, C. J. |
spellingShingle |
Sandholt, P. E. Dyrland, M. Farrugia, C. J. Dayside aurorae and polar arcs under south-east IMF orientation |
author_facet |
Sandholt, P. E. Dyrland, M. Farrugia, C. J. |
author_sort |
Sandholt, P. E. |
title |
Dayside aurorae and polar arcs under south-east IMF orientation |
title_short |
Dayside aurorae and polar arcs under south-east IMF orientation |
title_full |
Dayside aurorae and polar arcs under south-east IMF orientation |
title_fullStr |
Dayside aurorae and polar arcs under south-east IMF orientation |
title_full_unstemmed |
Dayside aurorae and polar arcs under south-east IMF orientation |
title_sort |
dayside aurorae and polar arcs under south-east imf orientation |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-24-3421-2006 https://angeo.copernicus.org/articles/24/3421/2006/ |
geographic |
Greenland Ny-Ålesund Svalbard |
geographic_facet |
Greenland Ny-Ålesund Svalbard |
genre |
Greenland Ny Ålesund Ny-Ålesund Svalbard |
genre_facet |
Greenland Ny Ålesund Ny-Ålesund Svalbard |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-24-3421-2006 https://angeo.copernicus.org/articles/24/3421/2006/ |
op_doi |
https://doi.org/10.5194/angeo-24-3421-2006 |
container_title |
Annales Geophysicae |
container_volume |
24 |
container_issue |
12 |
container_start_page |
3421 |
op_container_end_page |
3432 |
_version_ |
1766019407450996736 |