Hall‐induced inductive shielding effect on geomagnetic pulsations

Yoshikawa, Akimasa; Obana, Yuki; Shinohara, Masanao; Itonaga, M.; Yumoto, K.

doi:10.1029/2001gl013610

Cited by 16 publications

(24 citation statements)

References 12 publications

(26 reference statements)

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“…These parameters are similar to those found in Yoshikawa et al (2002), where c 2 −k 2 ⊥ )/µ 0 ω is the wave conductance in the atmosphere. The expression involving our wave mode conversion matrix in Eqs.…”

Section: Vertical Background Magnetic Fieldsupporting

confidence: 70%

“…We now consider the ISE as described by Itonaga (1996, 2000) and Yoshikawa et al (2002), who formulated their solutions for a vertical B 0 . When I =±90 • , Eqs.…”

Section: Vertical Background Magnetic Fieldmentioning

confidence: 99%

“…The ISE for a vertical B 0 was discussed by Itonaga (1996, 2000) and Yoshikawa et al (2002). These authors developed an expression for the ground magnetic field as…”

Section: Introductionmentioning

confidence: 99%

“…The time scale, γ −1 , becomes an indicator of the inductive effect, which is large for small k ⊥ , large α P = P a and large α H = H P . Yoshikawa et al (2002) showed that for a vertical B 0 , the inductive response of the ionosphere shielded the ground magnetic wave fields for frequencies ∼ 20-100 mHz and a highly conducting ionosphere.…”

Section: Introductionmentioning

confidence: 99%

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Propagation of ULF waves through the ionosphere: Inductive effect for oblique magnetic fields

2004

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Abstract. Solutions for ultra-low frequency (ULF) wave fields in the frequency range 1-100 mHz that interact with the Earth's ionosphere in the presence of oblique background magnetic fields are described. Analytic expressions for the electric and magnetic wave fields in the magnetosphere, ionosphere and atmosphere are derived within the context of an inductive ionosphere. The inductive shielding effect (ISE) arises from the generation of an "inductive" rotational current by the induced part of the divergent electric field in the ionosphere which reduces the wave amplitude detected on the ground. The inductive response of the ionosphere is described by Faraday's law and the ISE depends on the horizontal scale size of the ULF disturbance, its frequency and the ionosphere conductivities. The ISE for ULF waves in a vertical background magnetic field is limited in application to high latitudes. In this paper we examine the ISE within the context of oblique background magnetic fields, extending studies of an inductive ionosphere and the associated shielding of ULF waves to lower latitudes. It is found that the dip angle of the background magnetic field has a significant effect on signals detected at the ground. For incident shear Alfvén mode waves and oblique background magnetic fields, the horizontal component of the field-aligned current contributes to the signal detected at the ground. At low latitudes, the ISE is larger at smaller conductivity values compared with high latitudes.

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Section: Vertical Background Magnetic Fieldsupporting

confidence: 70%

“…We now consider the ISE as described by Itonaga (1996, 2000) and Yoshikawa et al (2002), who formulated their solutions for a vertical B 0 . When I =±90 • , Eqs.…”

Section: Vertical Background Magnetic Fieldmentioning

confidence: 99%

“…The ISE for a vertical B 0 was discussed by Itonaga (1996, 2000) and Yoshikawa et al (2002). These authors developed an expression for the ground magnetic field as…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Propagation of ULF waves through the ionosphere: Inductive effect for oblique magnetic fields

2004

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“…An inductive shielding effect (ISE) was discussed by Yoshikawa et al (2002) for the case where B 0 is vertical. The ISE may be understood in terms of the properties of the ULF wave electric field, E. If ∇ × E is significant, then Faraday's inductive term causes a reduction in amplitude of the waves seen on the ground compared with those in the magnetosphere (Yoshikawa andItonaga, 1996, 2000;Sciffer et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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

2013

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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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