Tidal variations in the high-latitude E- and F-region observed by EISCAT
During the MLTCS (Mesosphere-Lower Thermosphere Coupling Study) campaign the EISCAT UHF radar was continuously operated over 7 days (30 July–5 August 1992) in the CP-1 mode. The long time series obtained of the fundamental ionospheric parameters field-aligned ion velocity ( V i ), ion and electron t...
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ftdoajarticles:oai:doaj.org/article:85387cf2bf2244c699188bac1865c897 2023-05-15T16:04:31+02:00 Tidal variations in the high-latitude E- and F-region observed by EISCAT Klemens Hocke https://doaj.org/article/85387cf2bf2244c699188bac1865c897 EN eng Copernicus Publications http://www.ann-geophys.net/14/201/1996/angeo-14-201-1996.html https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 0992-7689 1432-0576 https://doaj.org/article/85387cf2bf2244c699188bac1865c897 Annales Geophysicae, Vol 14, Iss 2, Pp 201-210 (0000) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article ftdoajarticles 2022-12-31T09:10:00Z During the MLTCS (Mesosphere-Lower Thermosphere Coupling Study) campaign the EISCAT UHF radar was continuously operated over 7 days (30 July–5 August 1992) in the CP-1 mode. The long time series obtained of the fundamental ionospheric parameters field-aligned ion velocity ( V i ), ion and electron temperature ( T and T e ), and electron density ( N e ) are useful in investigating tidal variations in the E- and F-region since the geomagnetic activity was particularly low during the time of measurement. Maximum entropy spectra of the parameters were calculated for the relatively quiet interval from 1 August to 4 August 1992 and indicated dominant variations with harmonics of 24 hours. In the electron density spectrum especially, harmonics up to the sixth order (4-h period) are clearly visible. The phase and amplitude height profiles (100–450 km) of the diurnal, semidiurnal, and terdiurnal variations were determined by Fourier transform for a 24-h data set beginning at 12:00 UT on 3 August 1992 when the contaminating influences of electric fields were negligible. The tidal variations of the ion temperatures are compared with the corresponding variations of the neutral temperature predicted by the MSISE-90 model. A remarkable result is the dominance of terdiurnal temperature oscillations at E-region heights on 3–4 August 1992, while the measured diurnal and semidiurnal variations were negligible. The finding was confirmed by the analysis of further EISCAT data (2–3 August 1989, 2–3 July 1990, 31 March–1 April 1992) which also showed a dominant terdiurnal temperature tide in the E-region. This is different from numerous observations of tides in the E-region at mid-latitudes where the diurnal and especially the semidiurnal temperature oscillations were dominant. Article in Journal/Newspaper EISCAT Directory of Open Access Journals: DOAJ Articles |
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Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
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Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 Klemens Hocke Tidal variations in the high-latitude E- and F-region observed by EISCAT |
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Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
During the MLTCS (Mesosphere-Lower Thermosphere Coupling Study) campaign the EISCAT UHF radar was continuously operated over 7 days (30 July–5 August 1992) in the CP-1 mode. The long time series obtained of the fundamental ionospheric parameters field-aligned ion velocity ( V i ), ion and electron temperature ( T and T e ), and electron density ( N e ) are useful in investigating tidal variations in the E- and F-region since the geomagnetic activity was particularly low during the time of measurement. Maximum entropy spectra of the parameters were calculated for the relatively quiet interval from 1 August to 4 August 1992 and indicated dominant variations with harmonics of 24 hours. In the electron density spectrum especially, harmonics up to the sixth order (4-h period) are clearly visible. The phase and amplitude height profiles (100–450 km) of the diurnal, semidiurnal, and terdiurnal variations were determined by Fourier transform for a 24-h data set beginning at 12:00 UT on 3 August 1992 when the contaminating influences of electric fields were negligible. The tidal variations of the ion temperatures are compared with the corresponding variations of the neutral temperature predicted by the MSISE-90 model. A remarkable result is the dominance of terdiurnal temperature oscillations at E-region heights on 3–4 August 1992, while the measured diurnal and semidiurnal variations were negligible. The finding was confirmed by the analysis of further EISCAT data (2–3 August 1989, 2–3 July 1990, 31 March–1 April 1992) which also showed a dominant terdiurnal temperature tide in the E-region. This is different from numerous observations of tides in the E-region at mid-latitudes where the diurnal and especially the semidiurnal temperature oscillations were dominant. |
format |
Article in Journal/Newspaper |
author |
Klemens Hocke |
author_facet |
Klemens Hocke |
author_sort |
Klemens Hocke |
title |
Tidal variations in the high-latitude E- and F-region observed by EISCAT |
title_short |
Tidal variations in the high-latitude E- and F-region observed by EISCAT |
title_full |
Tidal variations in the high-latitude E- and F-region observed by EISCAT |
title_fullStr |
Tidal variations in the high-latitude E- and F-region observed by EISCAT |
title_full_unstemmed |
Tidal variations in the high-latitude E- and F-region observed by EISCAT |
title_sort |
tidal variations in the high-latitude e- and f-region observed by eiscat |
publisher |
Copernicus Publications |
url |
https://doaj.org/article/85387cf2bf2244c699188bac1865c897 |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
Annales Geophysicae, Vol 14, Iss 2, Pp 201-210 (0000) |
op_relation |
http://www.ann-geophys.net/14/201/1996/angeo-14-201-1996.html https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 0992-7689 1432-0576 https://doaj.org/article/85387cf2bf2244c699188bac1865c897 |
_version_ |
1766400106489184256 |