Magnetic-inclination effects in the spectral resonance structure of the ionospheric Alfvén resonator

Bösinger, T.; Ermakova, E. N.; Haldoupis, C.; Kotik, D. S.

doi:10.5194/angeo-27-1313-2009

Cited by 15 publications

(6 citation statements)

References 19 publications

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“…The influence of IAR on the ground electromagnetic field was examined originally in the frameworks of models, where the bottom ionosphere was modeled as a thin current sheet with height‐integrated Pedersen and Hall conductances [e.g., Polyakov et al , ]. Then, more realistic profiles of the ULF wave refraction index were derived from various ionospheric models [e.g., Ermakova et al , ; Bösinger et al , ; Mursula et al , ; Lysak et al , ].…”

Section: Earlier Models Of the Iar Excitation By Lightningmentioning

confidence: 99%

Modeling the high‐latitude ground response to the excitation of the ionospheric MHD modes by atmospheric electric discharge

et al. 2016

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The ionospheric Alfvén resonator (IAR) and fast magnetosonic (FMS) waveguide, which can trap the electromagnetic wave energy in the range from fractions of Hz to several Hz, are characteristic features of the upper ionosphere. Their role in the electromagnetic impulsive coupling between atmospheric discharge processes and the ionosphere can be elucidated with a proper model. The presented model is based on numerical solution of coupled wave equations for electromagnetic modes in the ionosphere and atmosphere in a realistic ionosphere modeled with the use of IRI (International Reference Ionosphere) vertical profiles. The geomagnetic field is supposed to be nearly vertical, so the model can be formally applied to high latitudes, though the main features of ground ULF structure will be qualitatively similar at middle latitudes as well. The modeling shows that during the lightning discharge a coupled wave system comprising IAR and MHD waveguide is excited. Using the model, the spatial structure, frequency spectra, and polarization parameters have been calculated at various distances from a vertical dipole. In the lightning proximity (about several hundred kilometer) only the lowest IAR harmonics are revealed in the radial magnetic component spectra. At distances >800 km the multiband spectral structure is formed predominantly by harmonics of FMS waveguide modes. The model predictions do not contradict the results of search coil magnetometer observations on Svalbard; however, the model validation demands more dedicated experimental studies.

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Section: Earlier Models Of the Iar Excitation By Lightningmentioning

confidence: 99%

Modeling the high‐latitude ground response to the excitation of the ionospheric MHD modes by atmospheric electric discharge

et al. 2016

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“…Further theoretical models have been developed (e.g. Lysak, 1993;Bösinger et al, 2009) to explain the phenomenon, and experimental work has provided evidence for their occurrence at low (Bösinger et al, 2002), middle (Kulak et al, 1999;Hebden et al, 2005) and high latitudes (Belyaev et al, 1999;Yahnin et al, 2003;Molchanov et al, 2004) in the Northern Hemisphere. Other researchers have shown SRSs are present in the Southern Hemisphere; for example, Yaun (2011) investigated SRSs measured at Halley Bay in Antarctica.…”

Section: Introductionmentioning

confidence: 99%

Automatic detection of ionospheric Alfvén resonances using signal and image processing techniques

Beggan

2014

Ann. Geophys.

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Abstract. Induction coils permit the measurement of small and very rapid changes of the magnetic field. A new set of induction coils in the UK (at L = 3.2) record magnetic field changes over an effective frequency range of 0.1-40 Hz, encompassing phenomena such as the Schumann resonances, magnetospheric pulsations and ionospheric Alfvén resonances (IARs). The IARs typically manifest themselves as a series of spectral resonance structures (SRSs) within the 1-10 Hz frequency range, usually appearing as fine bands or fringes in spectrogram plots and occurring almost daily during local night-time, disappearing during the daylight hours. The behaviour of the occurrence in frequency (f ) and the difference in frequency between fringes ( f ) varies throughout the year. In order to quantify the daily, seasonal and annual changes of the SRSs, we developed a new method based on signal and image processing techniques to identify the fringes and to quantify the values of f , f and other relevant parameters in the data set. The technique is relatively robust to noise though requires tuning of threshold parameters. We analyse 18 months of induction coil data to demonstrate the utility of the method.

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“…3 that the sharper decay not only increases the oscillation depth and the frequency interval, in which the resonant structure of the spectrum is observed, but also changes the sort of oscillations, leading to the appearance of additional peaks and non-equidistancy in the resonant structures. Such a form of the spectra is rather often observed at the reception point on Crete [11]. Thus, by varying the mode of decay of the charged-particle density in the ionosphere at altitudes higher than the F -layer maximum during modeling, we can choose the model profiles which describe most adequately the resonant structures observed in the experiment.…”

Section: Results Of Numerical Calculations For Different Ionospheric mentioning

confidence: 96%

Studying spectral structures in the background ultralow-frequency noise at different latitudes

Ermakova

Polyakov

Kotik

2011

Radiophys Quantum El

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550.383We numerically calculate the horizontal components of the magnetic field in the frequency range 0.1-15 Hz for reception points located at different geographical latitudes. For calculations, we used the solution of the problem on excitation of the Earth -vertically nonuniform anisotropic ionosphere waveguide by a source like a vertical electrical dipole [1]. Calculations were carried out for different numerical and analytical models of the ionospheric parameter profiles [2]. The results of modeling and experimental studies of the spectral resonant structure at the stations on Crete (35.15 N, 25.20 E), New Life (Nizhny Novgorod region, 55.97 N, 45.74 E), Lovozero (68 N, 35 E), and Barentsburg (78.09 N, 14.12 E) were compared. The degree of conformity of the different model profiles to the actual ones was revealed from a comparison of theoretical and experimental spectra. The studies were complemented by an analysis of calculated and experimental spectra of the magnetic noise polarization parameter.

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Magnetic-inclination effects in the spectral resonance structure of the ionospheric Alfvén resonator

Cited by 15 publications

References 19 publications

Modeling the high‐latitude ground response to the excitation of the ionospheric MHD modes by atmospheric electric discharge

Modeling the high‐latitude ground response to the excitation of the ionospheric MHD modes by atmospheric electric discharge

Automatic detection of ionospheric Alfvén resonances using signal and image processing techniques

Studying spectral structures in the background ultralow-frequency noise at different latitudes

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