A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters
International audience Resonance features of the Ionospheric Alfvén Resonator (IAR) can be observed in pulsation magnetometer data from Sodankylä, Finland using dynamic spectra visualizations. IAR resonance features were identified on 13 of 30 days in October 1998, with resonance structures lasting...
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ftccsdartic:oai:HAL:hal-00317823v1 2023-11-12T04:26:10+01:00 A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters Hebden, S. R. Robinson, T. R. Wright, D. M. Yeoman, T. Raita, T. Bösinger, T. Department of Physics and Astronomy Leicester University of Leicester Sodankylä Geophysical Observatory University of Oulu Dept. of Phys. Sciences Div. of Physics 2005-07-28 https://hal.science/hal-00317823 https://hal.science/hal-00317823/document https://hal.science/hal-00317823/file/angeo-23-1711-2005.pdf en eng HAL CCSD European Geosciences Union hal-00317823 https://hal.science/hal-00317823 https://hal.science/hal-00317823/document https://hal.science/hal-00317823/file/angeo-23-1711-2005.pdf info:eu-repo/semantics/OpenAccess ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317823 Annales Geophysicae, 2005, 23 (5), pp.1711-1721 [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 2005 ftccsdartic 2023-10-21T23:07:07Z International audience Resonance features of the Ionospheric Alfvén Resonator (IAR) can be observed in pulsation magnetometer data from Sodankylä, Finland using dynamic spectra visualizations. IAR resonance features were identified on 13 of 30 days in October 1998, with resonance structures lasting for 3 or more hours over 10 intervals. The diurnal evolution of the harmonic features was quantified for these 10 intervals using a manual cursor-clicking technique. The resonance features displayed strong linear relationships between harmonic frequency and harmonic number for all of the time intervals studied, enabling a homogeneous cavity model for the IAR to be adopted to interpret the data. This enabled the diurnal variation of the effective size of the IAR to be obtained for each of the 10 time intervals. The average effective size was found to be 530 km, and to have an average variation of 32% over each time interval: small compared to the average variation in Alfvén velocity of 61%. Thus the diurnal variation of the harmonics is chiefly caused by the changing plasma density within the IAR due to changing insolation. This study confirms Odzimek (2004) that the dominating factor affecting the IAR eigenfrequencies is the variation in the Alfvén velocity at the F-layer ion-density peak, with the changing IAR size affecting the IAR eigenfrequencies to a smaller extent. Another IAR parameter was derived from the analysis of the IAR resonance features associated with the phase matching structure of the standing waves in the IAR. This parameter varied over the time intervals studied by 20% on average, possibly due to changing ionospheric conductivity. Keywords. Ionosphere (Auroral ionosphere;Wave propagation) ? Radio science (Electromagnetic noise and interference) Article in Journal/Newspaper Sodankylä Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Sodankylä ENVELOPE(26.600,26.600,67.417,67.417) |
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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 Hebden, S. R. Robinson, T. R. Wright, D. M. Yeoman, T. Raita, T. Bösinger, T. A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience Resonance features of the Ionospheric Alfvén Resonator (IAR) can be observed in pulsation magnetometer data from Sodankylä, Finland using dynamic spectra visualizations. IAR resonance features were identified on 13 of 30 days in October 1998, with resonance structures lasting for 3 or more hours over 10 intervals. The diurnal evolution of the harmonic features was quantified for these 10 intervals using a manual cursor-clicking technique. The resonance features displayed strong linear relationships between harmonic frequency and harmonic number for all of the time intervals studied, enabling a homogeneous cavity model for the IAR to be adopted to interpret the data. This enabled the diurnal variation of the effective size of the IAR to be obtained for each of the 10 time intervals. The average effective size was found to be 530 km, and to have an average variation of 32% over each time interval: small compared to the average variation in Alfvén velocity of 61%. Thus the diurnal variation of the harmonics is chiefly caused by the changing plasma density within the IAR due to changing insolation. This study confirms Odzimek (2004) that the dominating factor affecting the IAR eigenfrequencies is the variation in the Alfvén velocity at the F-layer ion-density peak, with the changing IAR size affecting the IAR eigenfrequencies to a smaller extent. Another IAR parameter was derived from the analysis of the IAR resonance features associated with the phase matching structure of the standing waves in the IAR. This parameter varied over the time intervals studied by 20% on average, possibly due to changing ionospheric conductivity. Keywords. Ionosphere (Auroral ionosphere;Wave propagation) ? Radio science (Electromagnetic noise and interference) |
author2 |
Department of Physics and Astronomy Leicester University of Leicester Sodankylä Geophysical Observatory University of Oulu Dept. of Phys. Sciences Div. of Physics |
format |
Article in Journal/Newspaper |
author |
Hebden, S. R. Robinson, T. R. Wright, D. M. Yeoman, T. Raita, T. Bösinger, T. |
author_facet |
Hebden, S. R. Robinson, T. R. Wright, D. M. Yeoman, T. Raita, T. Bösinger, T. |
author_sort |
Hebden, S. R. |
title |
A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters |
title_short |
A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters |
title_full |
A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters |
title_fullStr |
A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters |
title_full_unstemmed |
A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters |
title_sort |
quantitative analysis of the diurnal evolution of ionospheric alfvén resonator magnetic resonance features and calculation of changing iar parameters |
publisher |
HAL CCSD |
publishDate |
2005 |
url |
https://hal.science/hal-00317823 https://hal.science/hal-00317823/document https://hal.science/hal-00317823/file/angeo-23-1711-2005.pdf |
long_lat |
ENVELOPE(26.600,26.600,67.417,67.417) |
geographic |
Sodankylä |
geographic_facet |
Sodankylä |
genre |
Sodankylä |
genre_facet |
Sodankylä |
op_source |
ISSN: 0992-7689 EISSN: 1432-0576 Annales Geophysicae https://hal.science/hal-00317823 Annales Geophysicae, 2005, 23 (5), pp.1711-1721 |
op_relation |
hal-00317823 https://hal.science/hal-00317823 https://hal.science/hal-00317823/document https://hal.science/hal-00317823/file/angeo-23-1711-2005.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782340258031992832 |