An inter-hemispheric, statistical study of nightside spectral width distributions from coherent HF scatter radars
International audience A statistical investigation of the Doppler spectral width parameter routinely observed by HF coherent radars has been conducted between the Northern and Southern Hemispheres for the nightside ionosphere. Data from the SuperDARN radars at Thykkvibær, Iceland and Syowa East, Ant...
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ftinsu:oai:HAL:hal-00317431v1 2023-11-12T04:03:08+01:00 An inter-hemispheric, statistical study of nightside spectral width distributions from coherent HF scatter radars Woodfield, E. E. Hosokawa, K. Milan, S. E. Sato, N. Lester, M. Department of Physics and Astronomy Leicester University of Leicester Department of Geophysics Kyoto Kyoto University National Institute of Polar Research Tokyo (NiPR) 2002 https://hal.science/hal-00317431 https://hal.science/hal-00317431/document https://hal.science/hal-00317431/file/angeo-20-1921-2002.pdf en eng HAL CCSD European Geosciences Union hal-00317431 https://hal.science/hal-00317431 https://hal.science/hal-00317431/document https://hal.science/hal-00317431/file/angeo-20-1921-2002.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317431 Annales Geophysicae, 2002, 20 (12), pp.1921-1934 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2002 ftinsu 2023-10-25T16:25:17Z International audience A statistical investigation of the Doppler spectral width parameter routinely observed by HF coherent radars has been conducted between the Northern and Southern Hemispheres for the nightside ionosphere. Data from the SuperDARN radars at Thykkvibær, Iceland and Syowa East, Antarctica have been employed for this purpose. Both radars frequently observe regions of high (>200 ms -1 ) spectral width polewards of low (<200 ms -1 ) spectral width. Three years of data from both radars have been analysed both for the spectral width and line of sight velocity. The pointing direction of these two radars is such that the flow reversal boundary may be estimated from the velocity data, and therefore, we have an estimate of the open/closed field line boundary location for comparison with the high spectral widths. Five key observations regarding the behaviour of the spectral width on the nightside have been made. These are (i) the two radars observe similar characteristics on a statistical basis; (ii) a latitudinal dependence related to magnetic local time is found in both hemispheres; (iii) a seasonal dependence of the spectral width is observed by both radars, which shows a marked absence of latitudinal dependence during the summer months; (iv) in general, the Syowa East spectral width tends to be larger than that from Iceland East, and (v) the highest spectral widths seem to appear on both open and closed field lines. Points (i) and (ii) indicate that the cause of high spectral width is magnetospheric in origin. Point (iii) suggests that either the propagation of the HF radio waves to regions of high spectral width or the generating mechanism(s) for high spectral width is affected by solar illumination or other seasonal effects. Point (iv) suggests that the radar beams from each of the radars are subject either to different instrumental or propagation effects, or different geophysical conditions due to their locations, although we suggest that this result is more likely to be due to geophysical ... Article in Journal/Newspaper Antarc* Antarctica East Antarctica Iceland Institut national des sciences de l'Univers: HAL-INSU East Antarctica |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Woodfield, E. E. Hosokawa, K. Milan, S. E. Sato, N. Lester, M. An inter-hemispheric, statistical study of nightside spectral width distributions from coherent HF scatter radars |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience A statistical investigation of the Doppler spectral width parameter routinely observed by HF coherent radars has been conducted between the Northern and Southern Hemispheres for the nightside ionosphere. Data from the SuperDARN radars at Thykkvibær, Iceland and Syowa East, Antarctica have been employed for this purpose. Both radars frequently observe regions of high (>200 ms -1 ) spectral width polewards of low (<200 ms -1 ) spectral width. Three years of data from both radars have been analysed both for the spectral width and line of sight velocity. The pointing direction of these two radars is such that the flow reversal boundary may be estimated from the velocity data, and therefore, we have an estimate of the open/closed field line boundary location for comparison with the high spectral widths. Five key observations regarding the behaviour of the spectral width on the nightside have been made. These are (i) the two radars observe similar characteristics on a statistical basis; (ii) a latitudinal dependence related to magnetic local time is found in both hemispheres; (iii) a seasonal dependence of the spectral width is observed by both radars, which shows a marked absence of latitudinal dependence during the summer months; (iv) in general, the Syowa East spectral width tends to be larger than that from Iceland East, and (v) the highest spectral widths seem to appear on both open and closed field lines. Points (i) and (ii) indicate that the cause of high spectral width is magnetospheric in origin. Point (iii) suggests that either the propagation of the HF radio waves to regions of high spectral width or the generating mechanism(s) for high spectral width is affected by solar illumination or other seasonal effects. Point (iv) suggests that the radar beams from each of the radars are subject either to different instrumental or propagation effects, or different geophysical conditions due to their locations, although we suggest that this result is more likely to be due to geophysical ... |
author2 |
Department of Physics and Astronomy Leicester University of Leicester Department of Geophysics Kyoto Kyoto University National Institute of Polar Research Tokyo (NiPR) |
format |
Article in Journal/Newspaper |
author |
Woodfield, E. E. Hosokawa, K. Milan, S. E. Sato, N. Lester, M. |
author_facet |
Woodfield, E. E. Hosokawa, K. Milan, S. E. Sato, N. Lester, M. |
author_sort |
Woodfield, E. E. |
title |
An inter-hemispheric, statistical study of nightside spectral width distributions from coherent HF scatter radars |
title_short |
An inter-hemispheric, statistical study of nightside spectral width distributions from coherent HF scatter radars |
title_full |
An inter-hemispheric, statistical study of nightside spectral width distributions from coherent HF scatter radars |
title_fullStr |
An inter-hemispheric, statistical study of nightside spectral width distributions from coherent HF scatter radars |
title_full_unstemmed |
An inter-hemispheric, statistical study of nightside spectral width distributions from coherent HF scatter radars |
title_sort |
inter-hemispheric, statistical study of nightside spectral width distributions from coherent hf scatter radars |
publisher |
HAL CCSD |
publishDate |
2002 |
url |
https://hal.science/hal-00317431 https://hal.science/hal-00317431/document https://hal.science/hal-00317431/file/angeo-20-1921-2002.pdf |
geographic |
East Antarctica |
geographic_facet |
East Antarctica |
genre |
Antarc* Antarctica East Antarctica Iceland |
genre_facet |
Antarc* Antarctica East Antarctica Iceland |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317431 Annales Geophysicae, 2002, 20 (12), pp.1921-1934 |
op_relation |
hal-00317431 https://hal.science/hal-00317431 https://hal.science/hal-00317431/document https://hal.science/hal-00317431/file/angeo-20-1921-2002.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782336243843989504 |