Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz
International audience 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 measur...
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ftccsdartic:oai:HAL:hal-00316682v1 2023-11-12T04:16:35+01:00 Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz Rüster, R. Schlegel, K. Max-Planck-Institut für Aeronomie (MPI Aeronomie) Max-Planck-Gesellschaft 1999 https://hal.science/hal-00316682 https://hal.science/hal-00316682/document https://hal.science/hal-00316682/file/angeo-17-1284-1999.pdf en eng HAL CCSD European Geosciences Union hal-00316682 https://hal.science/hal-00316682 https://hal.science/hal-00316682/document https://hal.science/hal-00316682/file/angeo-17-1284-1999.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00316682 Annales Geophysicae, 1999, 17 (10), pp.1284-1292 [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 1999 ftccsdartic 2023-10-21T23:08:17Z International audience 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. Article in Journal/Newspaper EISCAT Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Norway Alomar ENVELOPE(-67.083,-67.083,-68.133,-68.133) Farley ENVELOPE(-152.500,-152.500,-86.583,-86.583) |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
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 Rüster, R. Schlegel, K. Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience 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. |
author2 |
Max-Planck-Institut für Aeronomie (MPI Aeronomie) Max-Planck-Gesellschaft |
format |
Article in Journal/Newspaper |
author |
Rüster, R. Schlegel, K. |
author_facet |
Rüster, R. Schlegel, K. |
author_sort |
Rüster, R. |
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 |
HAL CCSD |
publishDate |
1999 |
url |
https://hal.science/hal-00316682 https://hal.science/hal-00316682/document https://hal.science/hal-00316682/file/angeo-17-1284-1999.pdf |
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 |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00316682 Annales Geophysicae, 1999, 17 (10), pp.1284-1292 |
op_relation |
hal-00316682 https://hal.science/hal-00316682 https://hal.science/hal-00316682/document https://hal.science/hal-00316682/file/angeo-17-1284-1999.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782333650177622016 |