Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study
The dynamics of the cusp region and post-noon sector for an interval of predominantly IMF B y , B z < 0 nT are studied with the CUTLASS Finland coherent HF radar, a meridian-scanning photometer located at Ny Ålesund, Svalbard, and a meridional network of magnetometers. The scanning mode of the ra...
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ftdoajarticles:oai:doaj.org/article:e9cdf83f2b954d8fa4dfb64b3be5635f 2023-05-15T17:48:29+02:00 Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study S. E. Milan M. Lester S. W. H. Cowley J. Moen P. E. Sandholt C. J. Owen 1999-02-01T00:00:00Z https://doi.org/10.1007/s00585-999-0159-5 https://doaj.org/article/e9cdf83f2b954d8fa4dfb64b3be5635f EN eng Copernicus Publications https://www.ann-geophys.net/17/159/1999/angeo-17-159-1999.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-999-0159-5 0992-7689 1432-0576 https://doaj.org/article/e9cdf83f2b954d8fa4dfb64b3be5635f Annales Geophysicae, Vol 17, Pp 159-172 (1999) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 1999 ftdoajarticles https://doi.org/10.1007/s00585-999-0159-5 2022-12-31T14:04:28Z The dynamics of the cusp region and post-noon sector for an interval of predominantly IMF B y , B z < 0 nT are studied with the CUTLASS Finland coherent HF radar, a meridian-scanning photometer located at Ny Ålesund, Svalbard, and a meridional network of magnetometers. The scanning mode of the radar is such that one beam is sampled every 14 s, and a 30° azimuthal sweep is completed every 2 minutes, all at 15 km range resolution. Both the radar backscatter and red line (630 nm) optical observations are closely co-located, especially at their equatorward boundary. The optical and radar aurora reveal three different behaviours which can interchange on the scale of minutes, and which are believed to be related to the dynamic nature of energy and momentum transfer from the solar wind to the magnetosphere through transient dayside reconnection. Two interpretations of the observations are presented, based upon the assumed location of the open/closed field line boundary (OCFLB). In the first, the OCFLB is co-located with equatorward boundary of the optical and radar aurora, placing most of the observations on open field lines. In the second, the observed aurora are interpreted as the ionospheric footprint of the region 1 current system, and the OCFLB is placed near the poleward edge of the radar backscatter and visible aurora; in this interpretation, most of the observations are placed on closed field lines, though transient brightenings of the optical aurora occur on open field lines. The observations reveal several transient features, including poleward and equatorward steps in the observed boundaries, "braiding" of the backscatter power, and 2 minute quasi-periodic enhancements of the plasma drift and optical intensity, predominantly on closed field lines. Key words. Ionosphere (auroral ionosphere; plasma convection) · Magnetospheric physics (magnetopause · cusp · and boundary layers) Article in Journal/Newspaper Ny Ålesund Ny-Ålesund Svalbard Directory of Open Access Journals: DOAJ Articles Ny-Ålesund Svalbard Annales Geophysicae 17 2 159 172 |
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Directory of Open Access Journals: DOAJ Articles |
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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 S. E. Milan M. Lester S. W. H. Cowley J. Moen P. E. Sandholt C. J. Owen Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
The dynamics of the cusp region and post-noon sector for an interval of predominantly IMF B y , B z < 0 nT are studied with the CUTLASS Finland coherent HF radar, a meridian-scanning photometer located at Ny Ålesund, Svalbard, and a meridional network of magnetometers. The scanning mode of the radar is such that one beam is sampled every 14 s, and a 30° azimuthal sweep is completed every 2 minutes, all at 15 km range resolution. Both the radar backscatter and red line (630 nm) optical observations are closely co-located, especially at their equatorward boundary. The optical and radar aurora reveal three different behaviours which can interchange on the scale of minutes, and which are believed to be related to the dynamic nature of energy and momentum transfer from the solar wind to the magnetosphere through transient dayside reconnection. Two interpretations of the observations are presented, based upon the assumed location of the open/closed field line boundary (OCFLB). In the first, the OCFLB is co-located with equatorward boundary of the optical and radar aurora, placing most of the observations on open field lines. In the second, the observed aurora are interpreted as the ionospheric footprint of the region 1 current system, and the OCFLB is placed near the poleward edge of the radar backscatter and visible aurora; in this interpretation, most of the observations are placed on closed field lines, though transient brightenings of the optical aurora occur on open field lines. The observations reveal several transient features, including poleward and equatorward steps in the observed boundaries, "braiding" of the backscatter power, and 2 minute quasi-periodic enhancements of the plasma drift and optical intensity, predominantly on closed field lines. Key words. Ionosphere (auroral ionosphere; plasma convection) · Magnetospheric physics (magnetopause · cusp · and boundary layers) |
format |
Article in Journal/Newspaper |
author |
S. E. Milan M. Lester S. W. H. Cowley J. Moen P. E. Sandholt C. J. Owen |
author_facet |
S. E. Milan M. Lester S. W. H. Cowley J. Moen P. E. Sandholt C. J. Owen |
author_sort |
S. E. Milan |
title |
Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study |
title_short |
Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study |
title_full |
Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study |
title_fullStr |
Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study |
title_full_unstemmed |
Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study |
title_sort |
meridian-scanning photometer, coherent hf radar, and magnetometer observations of the cusp: a case study |
publisher |
Copernicus Publications |
publishDate |
1999 |
url |
https://doi.org/10.1007/s00585-999-0159-5 https://doaj.org/article/e9cdf83f2b954d8fa4dfb64b3be5635f |
geographic |
Ny-Ålesund Svalbard |
geographic_facet |
Ny-Ålesund Svalbard |
genre |
Ny Ålesund Ny-Ålesund Svalbard |
genre_facet |
Ny Ålesund Ny-Ålesund Svalbard |
op_source |
Annales Geophysicae, Vol 17, Pp 159-172 (1999) |
op_relation |
https://www.ann-geophys.net/17/159/1999/angeo-17-159-1999.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-999-0159-5 0992-7689 1432-0576 https://doaj.org/article/e9cdf83f2b954d8fa4dfb64b3be5635f |
op_doi |
https://doi.org/10.1007/s00585-999-0159-5 |
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Annales Geophysicae |
container_volume |
17 |
container_issue |
2 |
container_start_page |
159 |
op_container_end_page |
172 |
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1766154559800999936 |