A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters
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...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2005-07-01
|
| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/23/1711/2005/angeo-23-1711-2005.pdf |
| _version_ | 1811242201014861824 |
|---|---|
| author | S. R. Hebden T. R. Robinson D. M. Wright T. Yeoman T. Raita T. Bösinger |
| author_facet | S. R. Hebden T. R. Robinson D. M. Wright T. Yeoman T. Raita T. Bösinger |
| author_sort | S. R. Hebden |
| collection | DOAJ |
| description | 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.<p>
<b>Keywords.</b> Ionosphere (Auroral ionosphere;Wave propagation)
– Radio science (Electromagnetic noise and interference) |
| first_indexed | 2024-04-12T13:48:21Z |
| format | Article |
| id | doaj.art-306029a81d104e42b81fbeb960cbfb86 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-04-12T13:48:21Z |
| publishDate | 2005-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-306029a81d104e42b81fbeb960cbfb862022-12-22T03:30:36ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762005-07-01231711172110.5194/angeo-23-1711-2005A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parametersS. R. Hebden0T. R. Robinson1D. M. Wright2T. Yeoman3T. Raita4T. Bösinger5Dept. of Phys. and Astronomy, Univ. of Leicester, Univ. Road, Leicester, LE1 7RH, UKDept. of Phys. and Astronomy, Univ. of Leicester, Univ. Road, Leicester, LE1 7RH, UKDept. of Phys. and Astronomy, Univ. of Leicester, Univ. Road, Leicester, LE1 7RH, UKDept. of Phys. and Astronomy, Univ. of Leicester, Univ. Road, Leicester, LE1 7RH, UKSodankylä Geophysical Observatory, Tähteläntie 62, 99600 Sodankylä , FinlandDept. of Phys. Sciences, Div. of Physics, Sect. of Space Phys. Res., P. O. Box 3000, 90014 University of Oulu, FinlandResonance 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.<p> <b>Keywords.</b> Ionosphere (Auroral ionosphere;Wave propagation) – Radio science (Electromagnetic noise and interference)https://www.ann-geophys.net/23/1711/2005/angeo-23-1711-2005.pdf |
| spellingShingle | S. R. Hebden T. R. Robinson D. M. Wright T. Yeoman T. Raita T. Bösinger A quantitative analysis of the diurnal evolution of Ionospheric Alfvén resonator magnetic resonance features and calculation of changing IAR parameters Annales Geophysicae |
| title | 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_short | 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 alfven resonator magnetic resonance features and calculation of changing iar parameters |
| url | https://www.ann-geophys.net/23/1711/2005/angeo-23-1711-2005.pdf |
| work_keys_str_mv | AT srhebden aquantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT trrobinson aquantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT dmwright aquantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT tyeoman aquantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT traita aquantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT tbosinger aquantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT srhebden quantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT trrobinson quantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT dmwright quantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT tyeoman quantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT traita quantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters AT tbosinger quantitativeanalysisofthediurnalevolutionofionosphericalfvenresonatormagneticresonancefeaturesandcalculationofchangingiarparameters |