First ground-based optical analysis of H β Doppler profiles close to local noon in the cusp
Observations of hydrogen emissions along the magnetic zenith at Longyearbyen (78.2 N, 15.8 E geographic) are used to investigate the energy and source of protons precipitating into the high latitude region. During the hours around local solar noon (11:00UT), measurements of the hydrogen Balmer β lin...
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ftdoajarticles:oai:doaj.org/article:beea9c2ae6f44d5fb62c3b5c13054ce4 2023-05-15T17:08:30+02:00 First ground-based optical analysis of H β Doppler profiles close to local noon in the cusp S. C. Robertson B. S. Lanchester M. Galand D. Lummerzheim A. B. Stockton-Chalk A. D. Aylward I. Furniss J. Baumgardner 2006-10-01T00:00:00Z https://doi.org/10.5194/angeo-24-2543-2006 https://doaj.org/article/beea9c2ae6f44d5fb62c3b5c13054ce4 EN eng Copernicus Publications https://www.ann-geophys.net/24/2543/2006/angeo-24-2543-2006.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-24-2543-2006 0992-7689 1432-0576 https://doaj.org/article/beea9c2ae6f44d5fb62c3b5c13054ce4 Annales Geophysicae, Vol 24, Pp 2543-2552 (2006) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2006 ftdoajarticles https://doi.org/10.5194/angeo-24-2543-2006 2022-12-30T21:51:07Z Observations of hydrogen emissions along the magnetic zenith at Longyearbyen (78.2 N, 15.8 E geographic) are used to investigate the energy and source of protons precipitating into the high latitude region. During the hours around local solar noon (11:00UT), measurements of the hydrogen Balmer β line are severely affected by sunlight, such that most data until now have been disregarded during these times. Here we use a simple technique to subtract sunlight contamination from such spectral data. An example is shown in which the removal of twilight contamination reveals a brightening of H β aurora over Svalbard on 27 November 2000 between 08:00UT and 10:00UT, which is centred on magnetic noon (08:48UT). These data were measured by the High Throughput Imaging Echelle Spectrograph (HiTIES), one instrument on the Southampton-UCL Spectrographic Imaging Facility (SIF). Data from the IMAGE satellite confirms the location of a cusp "spot" over Svalbard at the time of the ground-based measurements, which moved in response to changes in the IMF conditions. A coincident pass of the DMSP F12 satellite provided input spectra for modelling studies of the H β profiles, which confirm that the method for removing the twilight contamination is robust. The results described here are the first ground-based optical measurements of H β Doppler profiles from the cusp region close to local solar noon, when scattered sunlight swamps the raw data. Article in Journal/Newspaper Longyearbyen Svalbard Directory of Open Access Journals: DOAJ Articles Svalbard Longyearbyen Annales Geophysicae 24 10 2543 2552 |
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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 S. C. Robertson B. S. Lanchester M. Galand D. Lummerzheim A. B. Stockton-Chalk A. D. Aylward I. Furniss J. Baumgardner First ground-based optical analysis of H β Doppler profiles close to local noon in the cusp |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
Observations of hydrogen emissions along the magnetic zenith at Longyearbyen (78.2 N, 15.8 E geographic) are used to investigate the energy and source of protons precipitating into the high latitude region. During the hours around local solar noon (11:00UT), measurements of the hydrogen Balmer β line are severely affected by sunlight, such that most data until now have been disregarded during these times. Here we use a simple technique to subtract sunlight contamination from such spectral data. An example is shown in which the removal of twilight contamination reveals a brightening of H β aurora over Svalbard on 27 November 2000 between 08:00UT and 10:00UT, which is centred on magnetic noon (08:48UT). These data were measured by the High Throughput Imaging Echelle Spectrograph (HiTIES), one instrument on the Southampton-UCL Spectrographic Imaging Facility (SIF). Data from the IMAGE satellite confirms the location of a cusp "spot" over Svalbard at the time of the ground-based measurements, which moved in response to changes in the IMF conditions. A coincident pass of the DMSP F12 satellite provided input spectra for modelling studies of the H β profiles, which confirm that the method for removing the twilight contamination is robust. The results described here are the first ground-based optical measurements of H β Doppler profiles from the cusp region close to local solar noon, when scattered sunlight swamps the raw data. |
format |
Article in Journal/Newspaper |
author |
S. C. Robertson B. S. Lanchester M. Galand D. Lummerzheim A. B. Stockton-Chalk A. D. Aylward I. Furniss J. Baumgardner |
author_facet |
S. C. Robertson B. S. Lanchester M. Galand D. Lummerzheim A. B. Stockton-Chalk A. D. Aylward I. Furniss J. Baumgardner |
author_sort |
S. C. Robertson |
title |
First ground-based optical analysis of H β Doppler profiles close to local noon in the cusp |
title_short |
First ground-based optical analysis of H β Doppler profiles close to local noon in the cusp |
title_full |
First ground-based optical analysis of H β Doppler profiles close to local noon in the cusp |
title_fullStr |
First ground-based optical analysis of H β Doppler profiles close to local noon in the cusp |
title_full_unstemmed |
First ground-based optical analysis of H β Doppler profiles close to local noon in the cusp |
title_sort |
first ground-based optical analysis of h β doppler profiles close to local noon in the cusp |
publisher |
Copernicus Publications |
publishDate |
2006 |
url |
https://doi.org/10.5194/angeo-24-2543-2006 https://doaj.org/article/beea9c2ae6f44d5fb62c3b5c13054ce4 |
geographic |
Svalbard Longyearbyen |
geographic_facet |
Svalbard Longyearbyen |
genre |
Longyearbyen Svalbard |
genre_facet |
Longyearbyen Svalbard |
op_source |
Annales Geophysicae, Vol 24, Pp 2543-2552 (2006) |
op_relation |
https://www.ann-geophys.net/24/2543/2006/angeo-24-2543-2006.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-24-2543-2006 0992-7689 1432-0576 https://doaj.org/article/beea9c2ae6f44d5fb62c3b5c13054ce4 |
op_doi |
https://doi.org/10.5194/angeo-24-2543-2006 |
container_title |
Annales Geophysicae |
container_volume |
24 |
container_issue |
10 |
container_start_page |
2543 |
op_container_end_page |
2552 |
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1766064278760062976 |