Optical tomography of the aurora and EISCAT
Tomographic reconstruction of the three-dimensional auroral arc emission is used to obtain vertical and horizontal distributions of the optical auroral emission. Under the given experimental conditions with a very limited angular range and a small number of observers, algebraic reconstruction method...
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ftdoajarticles:oai:doaj.org/article:94d10f8245fb477ca3308f53154b32c6 2023-05-15T16:04:25+02:00 Optical tomography of the aurora and EISCAT H. U. Frey S. Frey B. S. Lanchester M. Kosch 1998-10-01T00:00:00Z https://doi.org/10.1007/s00585-998-1332-y https://doaj.org/article/94d10f8245fb477ca3308f53154b32c6 EN eng Copernicus Publications https://www.ann-geophys.net/16/1332/1998/angeo-16-1332-1998.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-998-1332-y 0992-7689 1432-0576 https://doaj.org/article/94d10f8245fb477ca3308f53154b32c6 Annales Geophysicae, Vol 16, Pp 1332-1342 (1998) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 1998 ftdoajarticles https://doi.org/10.1007/s00585-998-1332-y 2022-12-31T04:45:22Z Tomographic reconstruction of the three-dimensional auroral arc emission is used to obtain vertical and horizontal distributions of the optical auroral emission. Under the given experimental conditions with a very limited angular range and a small number of observers, algebraic reconstruction methods generally yield better results than transform techniques. Different algebraic reconstruction methods are tested with an auroral arc model and the best results are obtained with an iterative least-square method adapted from emission-computed tomography. The observation geometry used during a campaign in Norway in 1995 is tested with the arc model and root-mean-square errors, to be expected under the given geometrical conditions, are calculated. Although optimum geometry was not used, root-mean-square errors of less than 2% for the images and of the order of 30% for the distribution could be obtained. The method is applied to images from real observations. The correspondence of original pictures and projections of the reconstructed volume is discussed, and emission profiles along magnetic field lines through the three-dimensionally reconstructed arc are calibrated into electron density profiles with additional EISCAT measurements. Including a background profile and the temporal changes of the electron density due to recombination, good agreement can be obtained between measured profiles and the time-sequence of calculated profiles. These profiles are used to estimate the conductivity distribution in the vicinity of the EISCAT site. While the radar can only probe the ionosphere along the radar beam, the three-dimensional tomography enables conductivity estimates in a large area around the radar site. Key words. Tomography · Aurora · EISCAT · Ionosphere · Conductivity Article in Journal/Newspaper EISCAT Directory of Open Access Journals: DOAJ Articles Norway Annales Geophysicae 16 10 1332 1342 |
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 H. U. Frey S. Frey B. S. Lanchester M. Kosch Optical tomography of the aurora and EISCAT |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
Tomographic reconstruction of the three-dimensional auroral arc emission is used to obtain vertical and horizontal distributions of the optical auroral emission. Under the given experimental conditions with a very limited angular range and a small number of observers, algebraic reconstruction methods generally yield better results than transform techniques. Different algebraic reconstruction methods are tested with an auroral arc model and the best results are obtained with an iterative least-square method adapted from emission-computed tomography. The observation geometry used during a campaign in Norway in 1995 is tested with the arc model and root-mean-square errors, to be expected under the given geometrical conditions, are calculated. Although optimum geometry was not used, root-mean-square errors of less than 2% for the images and of the order of 30% for the distribution could be obtained. The method is applied to images from real observations. The correspondence of original pictures and projections of the reconstructed volume is discussed, and emission profiles along magnetic field lines through the three-dimensionally reconstructed arc are calibrated into electron density profiles with additional EISCAT measurements. Including a background profile and the temporal changes of the electron density due to recombination, good agreement can be obtained between measured profiles and the time-sequence of calculated profiles. These profiles are used to estimate the conductivity distribution in the vicinity of the EISCAT site. While the radar can only probe the ionosphere along the radar beam, the three-dimensional tomography enables conductivity estimates in a large area around the radar site. Key words. Tomography · Aurora · EISCAT · Ionosphere · Conductivity |
format |
Article in Journal/Newspaper |
author |
H. U. Frey S. Frey B. S. Lanchester M. Kosch |
author_facet |
H. U. Frey S. Frey B. S. Lanchester M. Kosch |
author_sort |
H. U. Frey |
title |
Optical tomography of the aurora and EISCAT |
title_short |
Optical tomography of the aurora and EISCAT |
title_full |
Optical tomography of the aurora and EISCAT |
title_fullStr |
Optical tomography of the aurora and EISCAT |
title_full_unstemmed |
Optical tomography of the aurora and EISCAT |
title_sort |
optical tomography of the aurora and eiscat |
publisher |
Copernicus Publications |
publishDate |
1998 |
url |
https://doi.org/10.1007/s00585-998-1332-y https://doaj.org/article/94d10f8245fb477ca3308f53154b32c6 |
geographic |
Norway |
geographic_facet |
Norway |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
Annales Geophysicae, Vol 16, Pp 1332-1342 (1998) |
op_relation |
https://www.ann-geophys.net/16/1332/1998/angeo-16-1332-1998.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-998-1332-y 0992-7689 1432-0576 https://doaj.org/article/94d10f8245fb477ca3308f53154b32c6 |
op_doi |
https://doi.org/10.1007/s00585-998-1332-y |
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Annales Geophysicae |
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16 |
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10 |
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1332 |
op_container_end_page |
1342 |
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1766400042343596032 |