Influence of the ionosphere on the altitude of discrete auroral arcs
The altitude of the maximum luminosity of single, discrete auroral arcs was measured by photometric triangulation from two stations (College and Fort Yukon, Alaska) located 226km apart on nearly the same magnetic meridian. The average height of the evening aurora decreases smoothly with increasing s...
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ftdoajarticles:oai:doaj.org/article:bbb5c677d7bd417d80cb3ba4a88ef09b 2023-05-15T18:49:00+02:00 Influence of the ionosphere on the altitude of discrete auroral arcs C. S. Deehr M. H. Rees A. E. H. Belon G. J. Romick D. Lummerzheim 2005-03-01T00:00:00Z https://doi.org/10.5194/angeo-23-759-2005 https://doaj.org/article/bbb5c677d7bd417d80cb3ba4a88ef09b EN eng Copernicus Publications https://www.ann-geophys.net/23/759/2005/angeo-23-759-2005.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-23-759-2005 0992-7689 1432-0576 https://doaj.org/article/bbb5c677d7bd417d80cb3ba4a88ef09b Annales Geophysicae, Vol 23, Pp 759-766 (2005) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2005 ftdoajarticles https://doi.org/10.5194/angeo-23-759-2005 2022-12-31T03:39:59Z The altitude of the maximum luminosity of single, discrete auroral arcs was measured by photometric triangulation from two stations (College and Fort Yukon, Alaska) located 226km apart on nearly the same magnetic meridian. The average height of the evening aurora decreases smoothly with increasing solar depression angle (sda) from 160km near 12° sda to 100km after 18° sda. The average height remains constant until around 12° sda in the morning. This diurnal variation is similar to that of the electron density in the F region of the ionosphere. Thus, the behavior is consistent with the concept that the mean auroral electron energy increases as the ionospheric conductivity decreases due to ionospheric recombination in the evening twilight. However, the mean electron energy decreases in magnitude at dawn when the solar ionizing radiation returns and the electron density in the F region increases. The magnetospheric acceleration mechanism associated with discrete auroral arcs thus appears to be inversely proportional to the ionospheric conductivity, because the time variation of the acceleration mechanism coincides with the local F region electron density and not with any obvious magnetospheric process. Previous auroral altitude observations, using similar triangulation methods, showed that the altitude of discrete auroral arcs increases as a function of latitude. When these data are corrected for the twilight effect, the dependence of altitude on latitude disappears. Thus, the average altitude of discrete auroral arcs and, by inference the magnetospheric auroral electron acceleration mechanism, is significantly influenced by the initial ionospheric conductance. Article in Journal/Newspaper Alaska Yukon Directory of Open Access Journals: DOAJ Articles Yukon Annales Geophysicae 23 3 759 766 |
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 C. S. Deehr M. H. Rees A. E. H. Belon G. J. Romick D. Lummerzheim Influence of the ionosphere on the altitude of discrete auroral arcs |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
The altitude of the maximum luminosity of single, discrete auroral arcs was measured by photometric triangulation from two stations (College and Fort Yukon, Alaska) located 226km apart on nearly the same magnetic meridian. The average height of the evening aurora decreases smoothly with increasing solar depression angle (sda) from 160km near 12° sda to 100km after 18° sda. The average height remains constant until around 12° sda in the morning. This diurnal variation is similar to that of the electron density in the F region of the ionosphere. Thus, the behavior is consistent with the concept that the mean auroral electron energy increases as the ionospheric conductivity decreases due to ionospheric recombination in the evening twilight. However, the mean electron energy decreases in magnitude at dawn when the solar ionizing radiation returns and the electron density in the F region increases. The magnetospheric acceleration mechanism associated with discrete auroral arcs thus appears to be inversely proportional to the ionospheric conductivity, because the time variation of the acceleration mechanism coincides with the local F region electron density and not with any obvious magnetospheric process. Previous auroral altitude observations, using similar triangulation methods, showed that the altitude of discrete auroral arcs increases as a function of latitude. When these data are corrected for the twilight effect, the dependence of altitude on latitude disappears. Thus, the average altitude of discrete auroral arcs and, by inference the magnetospheric auroral electron acceleration mechanism, is significantly influenced by the initial ionospheric conductance. |
format |
Article in Journal/Newspaper |
author |
C. S. Deehr M. H. Rees A. E. H. Belon G. J. Romick D. Lummerzheim |
author_facet |
C. S. Deehr M. H. Rees A. E. H. Belon G. J. Romick D. Lummerzheim |
author_sort |
C. S. Deehr |
title |
Influence of the ionosphere on the altitude of discrete auroral arcs |
title_short |
Influence of the ionosphere on the altitude of discrete auroral arcs |
title_full |
Influence of the ionosphere on the altitude of discrete auroral arcs |
title_fullStr |
Influence of the ionosphere on the altitude of discrete auroral arcs |
title_full_unstemmed |
Influence of the ionosphere on the altitude of discrete auroral arcs |
title_sort |
influence of the ionosphere on the altitude of discrete auroral arcs |
publisher |
Copernicus Publications |
publishDate |
2005 |
url |
https://doi.org/10.5194/angeo-23-759-2005 https://doaj.org/article/bbb5c677d7bd417d80cb3ba4a88ef09b |
geographic |
Yukon |
geographic_facet |
Yukon |
genre |
Alaska Yukon |
genre_facet |
Alaska Yukon |
op_source |
Annales Geophysicae, Vol 23, Pp 759-766 (2005) |
op_relation |
https://www.ann-geophys.net/23/759/2005/angeo-23-759-2005.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-23-759-2005 0992-7689 1432-0576 https://doaj.org/article/bbb5c677d7bd417d80cb3ba4a88ef09b |
op_doi |
https://doi.org/10.5194/angeo-23-759-2005 |
container_title |
Annales Geophysicae |
container_volume |
23 |
container_issue |
3 |
container_start_page |
759 |
op_container_end_page |
766 |
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