Alfv�n wave formation of small-scale inhomogeneities in the upper ionosphere at high latitudes

Gelberg, M. G.

doi:10.1007/bf01057081

Cited by 2 publications

(2 citation statements)

References 4 publications

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“…More studies should be done to differentiate the effects of forward scatter from the "background" scatter on field-aligned irregularities. The simple approach used here to describe the aspect angle dependence of auroral scatter in terms of the diffuse forward scatter effect is in contrast to a number of attempts to understand the dependence as a consequence only of the plasmaphysical properties of the spatial power spectra of anisotropic irregularities [Booker, 1956;Moorcroft, 1961;Gel'berg and Fedorov, 1983;Volosevich and Gel'berg, 1988; St.-Maurice, 1989]. It would seem that a combination both of plasmaphysical effects following the growth and stabilization of the anisotropic wave turbulence and of diffuse forward scatter and refraction effects, such as ionospheric refraction caused by wave trapping in curved ionospheric layers, is the most productive way of improving our understanding of the physics of coherent auroral backscatter.…”

Section: Troposphere (Mst) Radars As Polar Summer Mesospheric Echoes mentioning

confidence: 99%

An alternative look at the aspect sensitivity of auroral radar backscatter: A forward scatter effect

Uspensky¹,

Kustov²,

Sofko³

et al. 1993

J. Geophys. Res.

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A simple model for diffuse forward scatter is presented in order to account for the aspect ar•gle dependence of auroral radar backscatter over a wide range of aspect angles as can be observed by UHF radars. The basic assumption is that the backscatter itself is highly anisotropic but that the incident rays are partially scattered by quasi-isotropic small to medium scale irregularities in the bottom/top part of the E/D regions. The model is developed to provide a theoretical forward scatter/aspect angle relationship, which is compared with the observations. The model exhibits reasonable agreement with recent 440-MHz Millstone Hill radar observations over aspect angles ranging between 0 and 10 deg. Other supporting evidence is also presented.A summary of the most significant conclusions resulting from the previous work are the following: 1. At frequencies higher than about 100 MHz and at aspect angles of less than a few degrees, there is general agreement that aspect sensitivity is somewhere between 10 and 20 dB/deg with a mean value closer to about 10 dB/deg [Leadabrand et al., 1965; Chesnut, 1968; Pyatsi and Sverdlov, 1972; Mitchell and Brown, 1976; Foster et al., 1992]. 2. At aspect angles greater than a few degrees and mainly at frequencies lower than 100 MHz, there seems to be a greater variation in the numbers reported but the values are, in general, lower than 10 dB/deg [McDiarrnid, 1972; Jaye et al., 1969; Koehler et al., 1985]. More recently, new observations have been made at UHF and at large aspect angles [Moorcroft and Schlegel, 1990; Foster et al., 1992], which show that aspect sensitivity values are, themselves, a function of aspect angle. The functional dependence appears to be a monotonically decreasing value for aspect sensitivity as the aspect angles increase. Several workers have attempted to explain the aspect angle dependence as a consequence of a specific shape of the spatial irregularity autocorrelation function (ACF) [Booker, 1956; Moorcroft, 1961, 1985]. Other authors have applied plasmaphysical considerations involving nonlinear •On leave from Polar Geophysical Institute, Murmansk, Russia. Kelley, 1980; Gel'berg and Fedorov, 1983; Volosevich and Gel'berg, 1988; St.-Maurice, 1989; Robinson and Honary, Phys., 51,929-936, 1989. Villars, F., and V. F. Weisskopf, On the scattering of radio waves by turbulent fluctuations of the atmosphere, Proc. IRE, 1232-1239, 1955. Volosevich, A. V., and M. G. Gel'berg, Nonlinear interaction of electrostatic waves in the auroral E-region (in Itussian), lzv. VUZ, Radiophyz., 31, 550-554, 1988.

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Section: Troposphere (Mst) Radars As Polar Summer Mesospheric Echoes mentioning

confidence: 99%

An alternative look at the aspect sensitivity of auroral radar backscatter: A forward scatter effect

Uspensky¹,

Kustov²,

Sofko³

et al. 1993

J. Geophys. Res.

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show abstract

“…Transverse spatial size l ? of small-scale plasma inhomogeneties connected with fluctuations of fieldaligned currents can be found from the condition of equality of longitudinal and transverse resistances of the current circuit (Gel'berg, 1984). This circuit includes the field-aligned current of length L and the closing current in the lower ionosphere.…”

Section: Plasma Redistribution Caused By Field-aligned Currentmentioning

confidence: 99%

VLF transmitter signals as a possible tool for detection of seismic effects on the ionosphere

Chmyrev

Сорокин

Shklyar

2008

Journal of Atmospheric and Solar-Terrestrial Physics

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Alfv�n wave formation of small-scale inhomogeneities in the upper ionosphere at high latitudes

Cited by 2 publications

References 4 publications

An alternative look at the aspect sensitivity of auroral radar backscatter: A forward scatter effect

An alternative look at the aspect sensitivity of auroral radar backscatter: A forward scatter effect

VLF transmitter signals as a possible tool for detection of seismic effects on the ionosphere

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