Propagation of ULF waves through the ionosphere: Analytic solutions for oblique magnetic fields

Sciffer, M. D.; Waters, C. L.

doi:10.1029/2001ja000184

Cited by 49 publications

(78 citation statements)

References 30 publications

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“…After this initial period, the problem has also been studied for more general geometries of the background magnetic field (see, e.g., Leonovich and Mazur, 1991;Alperovich and Fedorov, 1993;Sciffer and Waters, 2002;Sciffer et al, 2004Sciffer et al, , 2005. Below we present a model and numerical results for the problem of magnetohydrodynamic wave transmission through and reflection from the ionosphere within a more realistic "thick ionosphere" model (Knudsen et al, 1992).…”

Section: Model Calculationsmentioning

confidence: 99%

Pc2-3 geomagnetic pulsations on the ground, in the ionosphere, and in the magnetosphere: MM100, CHAMP, and THEMIS observations

Yagova

Heilig²,

Fedorov

2015

Ann. Geophys.

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Abstract. We analyze Pc2-3 pulsations recorded by the CHAMP (CHAllenging Minisatellite Payload) satellite in the F layer of the Earth's ionosphere, on the ground, and in the magnetosphere during quiet geomagnetic conditions. The spectra of Pc2-3 pulsations recorded in the F layer are enriched with frequencies above 50 mHz in comparison to the ground Pc2-3 spectra. These frequencies are higher than the fundamental harmonics of the field line resonances in the magnetosphere. High quality signals with dominant frequencies 70-200 mHz are a regular phenomenon in the F layer and in the magnetosphere. The mean latitude of the maximum Pc2-3 occurrence rate lies at L ≈ 3.5 in the F layer, i.e., inside the plasmasphere. Day-to-day variations of the L value of the CHAMP Pc2-3 occurrence rate maximum follow the plasmapause day-to-day variations. Polarization and amplitude of Pc2-3s in the magnetosphere, in the ionosphere, and on the ground allow us to suggest that they are generated as fast magnetosonic (FMS) waves in the outer magnetosphere and are partly converted into shear Alfven waves near the plasmapause. The observed ground-to-ionosphere amplitude ratio during the night is interpreted as a result of the Alfven wave transmission through the ionosphere. The problem of wave transmission through the ionosphere is solved theoretically by means of a numerical solution of the full-wave equation for the Alfven wave reflection from and transmission through a horizontally stratified ionosphere. The best agreement between the calculated and measured values of the ground-to-ionosphere amplitude ratio is found for k = 5 × 10 −3 km −1 , i.e., the observed ground-to-ionosphere amplitude ratio corresponds to a wave spatial scale which could provide a Doppler shift within a few percent of the apparent frequency of the Pc2-3 pulsations as recorded by a loworbiting spacecraft.

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Section: Model Calculationsmentioning

confidence: 99%

Pc2-3 geomagnetic pulsations on the ground, in the ionosphere, and in the magnetosphere: MM100, CHAMP, and THEMIS observations

Yagova

Heilig²,

Fedorov

2015

Ann. Geophys.

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“…As an example, Hebden et al (2005) observed harmonics up to almost 5 Hz from magnetometer data obtained from Sodankylä, Finland. These observations can be modeled using the equations in a tilted magnetic field geometry such as those introduced by Sciffer and Waters (2002). While this earlier work considered a uniform plasma density above the ionosphere, to study the IAR we can include a density profile of the form…”

Section: Effects Of Hall Conductance On the Iarmentioning

confidence: 99%

“…For oblique magnetic field dip angles, the degeneracy between the two perpendicular directions is broken, since waves with wave vectors in the latitudinal direction, in the plane of the dipole field, differ from those in the longitudinal direction. Sciffer and Waters (2002) and Sciffer et al (2004) have analyzed the reflection and mode conversion of Alfvén and fast mode waves in the presence of oblique magnetic fields. They find a strong dependence on dip angle, especially for longitudinal propagation.…”

Section: Effects Of Hall Conductance On the Iarmentioning

confidence: 99%

“…The horizontal ionosphere electric field components, E 1 and E 2 , and the radial magnetic field component, b 3 are continuous across the ionosphere current sheet. The ionospheric boundary is given by (Hughes, 1974;Yoshikawa and Itonaga, 2000;Sciffer and Waters, 2002) …”

Section: Ulf Wave Modelmentioning

confidence: 99%

“…All these models assumed a vertical B 0 . The expressions for the reflection and mode conversion coefficients allowing for both fast and shear incident Alfvén wave modes, the inductive shielding effect and oblique B 0 were developed by Sciffer and Waters (2002) with typographic errors corrected in Sciffer et al (2004).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the coupling of fast and shear Alfvén wave modes by the ionospheric Hall conductance

2013

Self Cite

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There are two low frequency, magnetised, cold plasma wave modes that propagate through the Earth's magnetosphere. These are the compressional (fast) and the shear Alfvén modes. The fast mode distributes energy throughout the magnetosphere with the ability to propagate across the magnetic field. Previous studies of coupling between these two modes have often focussed on conditions necessary for mode coupling to occur in the magnetosphere. However, Kato and Tamao (1956) predicted mode coupling would occur for non-zero Hall currents. Recently, the importance of the Hall conductance in the ionosphere for low frequency wave propagation has been studied using one dimensional (1-D) models. In this paper we describe effects of the ionosphere Hall conductance on field line resonance and higher frequency, 0.1-5 Hz waves associated with the Ionospheric Alfvén Resonator (IAR). The Hall conductance reduces the damping time of field line resonances and Joule dissipation into the ionosphere. The Hall conductance also couples shear Alfvén waves trapped in the IAR to fast mode waves that propagate across the ambient magnetic field in an ionospheric waveguide. This coupling leads to the production of low frequency magnetic fields on the ground that can be observed by magnetometers.

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Pi2 pulsation simultaneously observed in the E and F region ionosphere with the SuperDARN Hokkaido radar

et al. 2014

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We investigated Pi2 pulsations in the nightside ionosphere that began at 14:15 UT (2315 LT) on 11 July 2010, and they were observed with high-temporal (8 s) resolution by beam 4 of the Super Dual Auroral Radar Network (SuperDARN) Hokkaido radar. These pulsations were simultaneously observed in both the ground/sea scatter echoes reflected from the F region height and in ionospheric echoes from field-aligned irregularities in the sporadic E s region. They had the same period of 110 s and approximately no phase lag. From the radar observations and the International Geomagnetic Reference Field model, the amplitude of the eastward (E EW ) component of the electric field of the Pi2 pulsations in the ionosphere was estimated~8.0 mV/m in the F region and~2.0 mV/m in the E region. Corresponding Pi2 pulsations appeared dominantly in the horizontal northward magnetic field component (H) at nearby ground stations, Moshiri (MSR), St. Paratunka (PTK), and Stecolny (STC), with amplitudes ranging from 6 nT (MSR) to 10 nT (STC). At the dominant frequency of 8.8 mHz, the coherences between H and E EW were high (>0.9), the cross phases of E EW relative to H were À56°a nd À45°, and the amplitude ratios were 2.7 × 10 5 m/s and 8.4 × 10 5 m/s, in the E and F regions, respectively.Based on a comparison of these results with theoretical predictions, we suggest that the concept of a pure cavity mode is not sufficient to explain the combined observations for midlatitude Pi2 waves and that the contribution of an Alfvén waves must be taken in account.

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Propagation of ULF waves through the ionosphere: Analytic solutions for oblique magnetic fields

Cited by 49 publications

References 30 publications

Pc2-3 geomagnetic pulsations on the ground, in the ionosphere, and in the magnetosphere: MM100, CHAMP, and THEMIS observations

Pc2-3 geomagnetic pulsations on the ground, in the ionosphere, and in the magnetosphere: MM100, CHAMP, and THEMIS observations

On the coupling of fast and shear Alfvén wave modes by the ionospheric Hall conductance

Pi2 pulsation simultaneously observed in the E and F region ionosphere with the SuperDARN Hokkaido radar

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