Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region
International audience The field-aligned neutral oscillations in the F -region (altitudes between 165 and 275 km) were compared using data obtained simultaneously with two independent instruments: the European Incoherent Scatter (EISCAT) UHF radar and a scanning Fabry-Perot interferometer (FPI). Dur...
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ftunivnantes:oai:HAL:hal-00329163v1 2023-05-15T16:04:31+02:00 Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region Oyama, S. Nozawa, S. Buchert, S. C. Ishii, M. Watari, S. Sagawa, E. Kofman, W. Lilensten, J. Fujii, R. Communications Research Laboratory 4-2-1 Solar-Terrestrial Environment Laboratory Nagoya (STEL) Nagoya University Laboratoire de Planétologie de Grenoble (LPG) Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) 2000 https://hal.science/hal-00329163 https://hal.science/hal-00329163/document https://hal.science/hal-00329163/file/angeo-18-1154-2000.pdf en eng HAL CCSD European Geosciences Union hal-00329163 https://hal.science/hal-00329163 https://hal.science/hal-00329163/document https://hal.science/hal-00329163/file/angeo-18-1154-2000.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00329163 Annales Geophysicae, 2000, 18 (9), pp.1154-1163 [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 2000 ftunivnantes 2023-02-08T04:19:58Z International audience The field-aligned neutral oscillations in the F -region (altitudes between 165 and 275 km) were compared using data obtained simultaneously with two independent instruments: the European Incoherent Scatter (EISCAT) UHF radar and a scanning Fabry-Perot interferometer (FPI). During the night of February 8, 1997, simultaneous observations with these instruments were conducted at Tromsø, Norway. Theoretically, the field-aligned neutral wind velocity can be obtained from the field-aligned ion velocity and by diffusion and ambipolar diffusion velocities. We thus derived field-aligned neutral wind velocities from the plasma velocities in EISCAT radar data. They were compared with those observed with the FPI ( ? =630.0 nm), which are assumed to be weighted height averages of the actual neutral wind. The weighting function is the normalized height dependent emission rate. We used two model weighting functions to derive the neutral wind from EISCAT data. One was that the neutral wind velocity observed with the FPI is velocity integrated over the entire emission layer and multiplied by the theoretical normalized emission rate. The other was that the neutral wind velocity observed with the FPI corresponds to the velocity only around an altitude where the emission rate has a peak. Differences between the two methods were identified, but not completely clarified. However, the neutral wind velocities from both instruments had peak-to-peak correspondences at oscillation periods of about 10–40 min, shorter than that for the momentum transfer from ions to neutrals, but longer than from neutrals to ions. The synchronizing motions in the neutral wind velocities suggest that the momentum transfer from neutrals to ions was thought to be dominant for the observed field-aligned oscillations rather than the transfer from ions to neutrals. It is concluded that during the observation, the plasma oscillations observed with the EISCAT radar at different altitudes in the F -region are thought to be due to the motion ... Article in Journal/Newspaper EISCAT Tromsø Université de Nantes: HAL-UNIV-NANTES Norway Tromsø |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
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 Oyama, S. Nozawa, S. Buchert, S. C. Ishii, M. Watari, S. Sagawa, E. Kofman, W. Lilensten, J. Fujii, R. Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience The field-aligned neutral oscillations in the F -region (altitudes between 165 and 275 km) were compared using data obtained simultaneously with two independent instruments: the European Incoherent Scatter (EISCAT) UHF radar and a scanning Fabry-Perot interferometer (FPI). During the night of February 8, 1997, simultaneous observations with these instruments were conducted at Tromsø, Norway. Theoretically, the field-aligned neutral wind velocity can be obtained from the field-aligned ion velocity and by diffusion and ambipolar diffusion velocities. We thus derived field-aligned neutral wind velocities from the plasma velocities in EISCAT radar data. They were compared with those observed with the FPI ( ? =630.0 nm), which are assumed to be weighted height averages of the actual neutral wind. The weighting function is the normalized height dependent emission rate. We used two model weighting functions to derive the neutral wind from EISCAT data. One was that the neutral wind velocity observed with the FPI is velocity integrated over the entire emission layer and multiplied by the theoretical normalized emission rate. The other was that the neutral wind velocity observed with the FPI corresponds to the velocity only around an altitude where the emission rate has a peak. Differences between the two methods were identified, but not completely clarified. However, the neutral wind velocities from both instruments had peak-to-peak correspondences at oscillation periods of about 10–40 min, shorter than that for the momentum transfer from ions to neutrals, but longer than from neutrals to ions. The synchronizing motions in the neutral wind velocities suggest that the momentum transfer from neutrals to ions was thought to be dominant for the observed field-aligned oscillations rather than the transfer from ions to neutrals. It is concluded that during the observation, the plasma oscillations observed with the EISCAT radar at different altitudes in the F -region are thought to be due to the motion ... |
author2 |
Communications Research Laboratory 4-2-1 Solar-Terrestrial Environment Laboratory Nagoya (STEL) Nagoya University Laboratoire de Planétologie de Grenoble (LPG) Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Oyama, S. Nozawa, S. Buchert, S. C. Ishii, M. Watari, S. Sagawa, E. Kofman, W. Lilensten, J. Fujii, R. |
author_facet |
Oyama, S. Nozawa, S. Buchert, S. C. Ishii, M. Watari, S. Sagawa, E. Kofman, W. Lilensten, J. Fujii, R. |
author_sort |
Oyama, S. |
title |
Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region |
title_short |
Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region |
title_full |
Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region |
title_fullStr |
Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region |
title_full_unstemmed |
Effects of atmospheric oscillations on the field-aligned ion motions in the polar F-region |
title_sort |
effects of atmospheric oscillations on the field-aligned ion motions in the polar f-region |
publisher |
HAL CCSD |
publishDate |
2000 |
url |
https://hal.science/hal-00329163 https://hal.science/hal-00329163/document https://hal.science/hal-00329163/file/angeo-18-1154-2000.pdf |
geographic |
Norway Tromsø |
geographic_facet |
Norway Tromsø |
genre |
EISCAT Tromsø |
genre_facet |
EISCAT Tromsø |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00329163 Annales Geophysicae, 2000, 18 (9), pp.1154-1163 |
op_relation |
hal-00329163 https://hal.science/hal-00329163 https://hal.science/hal-00329163/document https://hal.science/hal-00329163/file/angeo-18-1154-2000.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1766400089924829184 |