HF radar observations of high-aspect angle backscatter from the E-region
We present evidence for the observation of high-aspect angle HF radar backscatter from the auroral electrojets, and describe the spectral characteristics of these echoes. Such backscatter is observed at very near ranges where ionospheric refraction is not sufficient to bring the sounding radio waves...
Published in: | Annales Geophysicae |
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ftcopernicus:oai:publications.copernicus.org:angeo35134 2023-05-15T16:49:46+02:00 HF radar observations of high-aspect angle backscatter from the E-region Milan, S. E. Lester, M. Yeoman, T. K. Robinson, T. R. Uspensky, M. V. Villain, J.-P. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-22-829-2004 https://angeo.copernicus.org/articles/22/829/2004/ eng eng doi:10.5194/angeo-22-829-2004 https://angeo.copernicus.org/articles/22/829/2004/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-22-829-2004 2020-07-20T16:27:37Z We present evidence for the observation of high-aspect angle HF radar backscatter from the auroral electrojets, and describe the spectral characteristics of these echoes. Such backscatter is observed at very near ranges where ionospheric refraction is not sufficient to bring the sounding radio waves to orthogonality with the magnetic field; the frequency dependence of this propagation effect is investigated with the Stereo upgrade of the CUTLASS Iceland radar. We term the occurrence of such echoes the "high-aspect angle irregularity region" or HAIR. It is suggested that backscatter is observed at aspect angles as high as 30°, with an aspect sensitivity as low as 1dB deg –1 . These echoes are distinguished from normal electrojet backscatter by having low Doppler shifts with an azimuthal dependence that appears more consistent with the direction of the convection electric field than with the expected electron drift direction. This is discussed in terms of the linear theory dispersion relation for electrojet waves. Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; auroral ionosphere) Text Iceland Copernicus Publications: E-Journals Annales Geophysicae 22 3 829 847 |
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Open Polar |
collection |
Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
We present evidence for the observation of high-aspect angle HF radar backscatter from the auroral electrojets, and describe the spectral characteristics of these echoes. Such backscatter is observed at very near ranges where ionospheric refraction is not sufficient to bring the sounding radio waves to orthogonality with the magnetic field; the frequency dependence of this propagation effect is investigated with the Stereo upgrade of the CUTLASS Iceland radar. We term the occurrence of such echoes the "high-aspect angle irregularity region" or HAIR. It is suggested that backscatter is observed at aspect angles as high as 30°, with an aspect sensitivity as low as 1dB deg –1 . These echoes are distinguished from normal electrojet backscatter by having low Doppler shifts with an azimuthal dependence that appears more consistent with the direction of the convection electric field than with the expected electron drift direction. This is discussed in terms of the linear theory dispersion relation for electrojet waves. Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; auroral ionosphere) |
format |
Text |
author |
Milan, S. E. Lester, M. Yeoman, T. K. Robinson, T. R. Uspensky, M. V. Villain, J.-P. |
spellingShingle |
Milan, S. E. Lester, M. Yeoman, T. K. Robinson, T. R. Uspensky, M. V. Villain, J.-P. HF radar observations of high-aspect angle backscatter from the E-region |
author_facet |
Milan, S. E. Lester, M. Yeoman, T. K. Robinson, T. R. Uspensky, M. V. Villain, J.-P. |
author_sort |
Milan, S. E. |
title |
HF radar observations of high-aspect angle backscatter from the E-region |
title_short |
HF radar observations of high-aspect angle backscatter from the E-region |
title_full |
HF radar observations of high-aspect angle backscatter from the E-region |
title_fullStr |
HF radar observations of high-aspect angle backscatter from the E-region |
title_full_unstemmed |
HF radar observations of high-aspect angle backscatter from the E-region |
title_sort |
hf radar observations of high-aspect angle backscatter from the e-region |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-22-829-2004 https://angeo.copernicus.org/articles/22/829/2004/ |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-22-829-2004 https://angeo.copernicus.org/articles/22/829/2004/ |
op_doi |
https://doi.org/10.5194/angeo-22-829-2004 |
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Annales Geophysicae |
container_volume |
22 |
container_issue |
3 |
container_start_page |
829 |
op_container_end_page |
847 |
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1766039960056496128 |