Terrestrial extremely low frequency noise spectrum in the presence of exponential ionospheric conductivity profiles

Galejs, Janis

doi:10.1029/jz066i009p02787

Cited by 34 publications

(15 citation statements)

References 10 publications

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“…To illustrate this point, two single exponential profiles are employed in our FDTD model. The single exponential profile [Galejs, 1961] is given by…”

Section: Titanmentioning

confidence: 99%

Three‐dimensional finite difference time domain modeling of the Schumann resonance parameters on Titan, Venus, and Mars

2006

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[1] The conducting ionosphere and conducting surface of Titan, Venus, and Mars form a concentric resonator, which would support the possibility of the existence of global electromagnetic resonances. On Earth, such resonances are commonly referred to as Schumann resonances and are excited by lightning discharges. The detection of such resonances on other planets would give a support for the existence of the electrical discharges in the lower atmosphere on these planets. In this paper, a three-dimensional finite difference time domain modeling for the extremely low frequency propagation is employed to study the Schumann resonance problems on Titan, Venus, and Mars. The atmospheric conductivity profiles for these studies are derived from the previously reported ionospheric models for these planets. The Schumann resonance frequencies and Q factors on these planets are calculated and are critically compared with those obtained from the previously published models.

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“…To illustrate this point, two single exponential profiles are employed in our FDTD model. The single exponential profile [Galejs, 1961] is given by…”

Section: Titanmentioning

confidence: 99%

Three‐dimensional finite difference time domain modeling of the Schumann resonance parameters on Titan, Venus, and Mars

2006

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“…The isotropic exponential model gives a reasonable approximation to the ionospheric conductivity versus height profile through the lower ionosphere layers, and the propagation parameters of the model can be deter· mined from closed form expressions of the surface impedance [Galejs, 1961a[Galejs, , 1962a[Galejs, , b, 1964a]_ Calcu· lated resonance frequencies and Q factors that are based on (3), (4), and available values of 5 [Galejs, 1962a] are listed in tables I and II. Calculations are based on daytime or day and nighttime ionosphere models.…”

Section: Models Of Continuously Varying Ionospherementioning

confidence: 99%

Schumann resonances

Galejs¹

1965

J. RES. NATL. BUR. STAN. SECT. D. RAD. SCI.

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This paper re vi e ws the c urre nt work in the fi eld of Sc humann resonances and di sc usses the topi cs of waveforms and frequ e ncy es tim a tes , reso nance fre quen cies and Q fa ctors, sourc e dI strIbutIOn s and nois e spectra. diurnal and seaso nal c hanges of power spectra, and .variati ons of resonance frequ e ncIes . Obse rvation s of th e a bove ph e nome na a re co rre lat ed WIth th eore tI ca l co ns Id e ratIon s.

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“…This has prompted the introduction of gradually tapered ionosphere models by Wait [1960aWait [ , b , 1962 and Galejs [1961aGalejs [ , b , 1962 , which still h ave not consider ed the effects of ion motion and the earth 's magnetic field.The purpose of this p ap er is primarily to estim ate the probable effects on ELF propagation caused b y the earth's magnetic field in con1.bination wit h electron and ion densities which vary gradually with heigh t. To this end , normal quiet day and night models of the lower ionosphere are selected. The usual Appleton-Hartl'ee formulas for the electrical conductivity of a li gh tly ionized gas of different ionized species arc used.…”

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confidence: 99%

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“…A closed form solution is obtained for an ionosphere model of two inhomogeneous layers: the lower layer is assumed to be isotropic and the upper layer anisotropic. The treatment of the isotropic layer is based on solutions of Galejs [1961aGalejs [ , b, 1962 for an exponential conductivity-height profile. The assumed exponential height variation of the tensor conductivity components does not take into account the gradual levelingoff and decrease respectively of these components which is noted at heights above 100 km.…”

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Propagation of ELF waves below inhomogeneous anisotropic ionosphere

Galejs¹,

Row²

1964

J. RES. NATL. BUR. STAN. SECT. D. RAD. SCI.

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In the ELF range, the homogeneous, isotropic model ionosphere is not successful in explaining observed signal characteristics. This has prompted the introduction of gradually tapered ionosphere models by Wait [1960aWait [ , b , 1962 and Galejs [1961aGalejs [ , b , 1962 , which still h ave not consider ed the effects of ion motion and the earth 's magnetic field.The purpose of this p ap er is primarily to estim ate the probable effects on ELF propagation caused b y the earth's magnetic field in con1.bination wit h electron and ion densities which vary gradually with heigh t. To this end , normal quiet day and night models of the lower ionosphere are selected. The usual Appleton-Hartl'ee formulas for the electrical conductivity of a li gh tly ionized gas of different ionized species arc used. Assuming a static magnetic field Eo to act in the z direction th e Cartesian form of th e tensor permittiviLy for a harmonic field with time dependence exp (-iwt) is, The calculations of (T i are based on avail able electron and ion density and collision frequency data and result for daytime conditions in the curves shown in fig ure 1. The altitude variation of each of the three components of the tensor conductivity is seen to be nearly exponential through the lower part of th e ionosphere . The propagation in an inhomogeneous, anisotropic medium involves, in general, coupled differential equations which are difficult to solve. However, based on the sharply bounded uniform ionosphere, the most pronounced anisotropy effects may be expected for propagation along the magnetic equator [Wait and Spies, 1960c]. In this particular case the surface impedance (required for determination of the waveguide mode constants) at the lower edge of the anisotropic ionosphere can be derived from 1 The lull paper ap p ears in the J anuary 1964 issue of IEEE T ran sactions on Antennas and P ropagation. Th is work was su pported by the Office of Naval R esear cb undcr Contract Nonr 3185(00).

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Terrestrial extremely low frequency noise spectrum in the presence of exponential ionospheric conductivity profiles

Cited by 34 publications

References 10 publications

Three‐dimensional finite difference time domain modeling of the Schumann resonance parameters on Titan, Venus, and Mars

Three‐dimensional finite difference time domain modeling of the Schumann resonance parameters on Titan, Venus, and Mars

Schumann resonances

Propagation of ELF waves below inhomogeneous anisotropic ionosphere

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