Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz
Backscatter from E-region irregularities was observed at aspect angles close to 90° (almost parallel to the direction of the magnetic field) using the ALOMAR SOUSY radar at Andoya/Norway. Strong electric fields and increased E-region electron temperatures simultaneously measured with the incoherent...
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1999
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ftdoajarticles:oai:doaj.org/article:12ed2683df9d4b6090b6f8d6bd1fb1bf 2023-05-15T16:04:34+02:00 Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz R. Rüster K. Schlegel 1999-10-01T00:00:00Z https://doi.org/10.1007/s00585-999-1284-x https://doaj.org/article/12ed2683df9d4b6090b6f8d6bd1fb1bf EN eng Copernicus Publications https://www.ann-geophys.net/17/1284/1999/angeo-17-1284-1999.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-999-1284-x 0992-7689 1432-0576 https://doaj.org/article/12ed2683df9d4b6090b6f8d6bd1fb1bf Annales Geophysicae, Vol 17, Pp 1284-1292 (1999) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 1999 ftdoajarticles https://doi.org/10.1007/s00585-999-1284-x 2022-12-30T23:32:50Z Backscatter from E-region irregularities was observed at aspect angles close to 90° (almost parallel to the direction of the magnetic field) using the ALOMAR SOUSY radar at Andoya/Norway. Strong electric fields and increased E-region electron temperatures simultaneously measured with the incoherent scatter facility EISCAT proved that the Farley-Buneman plasma instability was excited. In addition, strong particle precipitation was present as inferred from EISCAT electron densities indicating that the gradient drift instability may have been active, too. Backscatter at such large aspect angles was not expected and has not been observed before. The characteristics of the observed echoes, however, are in many aspects completely different from usual auroral radar results: the Doppler velocities are only of the order of 10 m/s, the half-width of the spectra is around 5 m/s, the echoes originate at altitudes well below 100 km, and they seem to be not aspect-sensitive with respect to the magnetic field direction. We, therefore, conclude that the corresponding irregularities are not caused by the mentioned instabilities and that other mechanism have to be invoked. Key words. Ionosphere (plasma waves and instabilities; ionosphere irregularities; particle precipitaion) · Meteorology and atmospheric dynamics (middle atmosphere dynamics) Article in Journal/Newspaper EISCAT Directory of Open Access Journals: DOAJ Articles Norway Alomar ENVELOPE(-67.083,-67.083,-68.133,-68.133) Farley ENVELOPE(-152.500,-152.500,-86.583,-86.583) Annales Geophysicae 17 10 1284 1292 |
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 R. Rüster K. Schlegel Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
Backscatter from E-region irregularities was observed at aspect angles close to 90° (almost parallel to the direction of the magnetic field) using the ALOMAR SOUSY radar at Andoya/Norway. Strong electric fields and increased E-region electron temperatures simultaneously measured with the incoherent scatter facility EISCAT proved that the Farley-Buneman plasma instability was excited. In addition, strong particle precipitation was present as inferred from EISCAT electron densities indicating that the gradient drift instability may have been active, too. Backscatter at such large aspect angles was not expected and has not been observed before. The characteristics of the observed echoes, however, are in many aspects completely different from usual auroral radar results: the Doppler velocities are only of the order of 10 m/s, the half-width of the spectra is around 5 m/s, the echoes originate at altitudes well below 100 km, and they seem to be not aspect-sensitive with respect to the magnetic field direction. We, therefore, conclude that the corresponding irregularities are not caused by the mentioned instabilities and that other mechanism have to be invoked. Key words. Ionosphere (plasma waves and instabilities; ionosphere irregularities; particle precipitaion) · Meteorology and atmospheric dynamics (middle atmosphere dynamics) |
format |
Article in Journal/Newspaper |
author |
R. Rüster K. Schlegel |
author_facet |
R. Rüster K. Schlegel |
author_sort |
R. Rüster |
title |
Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz |
title_short |
Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz |
title_full |
Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz |
title_fullStr |
Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz |
title_full_unstemmed |
Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz |
title_sort |
non-magnetic aspect sensitive auroral echoes from the lower e region observed at 50 mhz |
publisher |
Copernicus Publications |
publishDate |
1999 |
url |
https://doi.org/10.1007/s00585-999-1284-x https://doaj.org/article/12ed2683df9d4b6090b6f8d6bd1fb1bf |
long_lat |
ENVELOPE(-67.083,-67.083,-68.133,-68.133) ENVELOPE(-152.500,-152.500,-86.583,-86.583) |
geographic |
Norway Alomar Farley |
geographic_facet |
Norway Alomar Farley |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
Annales Geophysicae, Vol 17, Pp 1284-1292 (1999) |
op_relation |
https://www.ann-geophys.net/17/1284/1999/angeo-17-1284-1999.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-999-1284-x 0992-7689 1432-0576 https://doaj.org/article/12ed2683df9d4b6090b6f8d6bd1fb1bf |
op_doi |
https://doi.org/10.1007/s00585-999-1284-x |
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Annales Geophysicae |
container_volume |
17 |
container_issue |
10 |
container_start_page |
1284 |
op_container_end_page |
1292 |
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1766400163666984960 |