On fractal properties of small-scale ionospheric irregularities

Myasnikov

et al. 2008

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We show the results of the first experimental studies of the multifractal structure of the developed artificial ionospheric turbulence. As a result of the special multifractal analysis of the recorded amplitudes of signals from the orbital satellites, which were obtained during the experiments on radio tomography of the irregularities excited in the ionosphere by the powerful mid-latitude heating facility "Sura," it is found that the characteristic multifractal structure of these records is caused by the nonuniform spatial distribution of the small-scale fluctuations of the electron number density in the artificial irregularities of the ionospheric plasma. Comparative analysis is performed for the multifractal spectra of fluctuations of both the amplitudes and energies of signals received from the orbital satellites upon radio transmission probing of the region of artificial ionospheric turbulence by these signals at three observation points located near the "Sura" heating facility and spaced apart to a distance of about 100-150 km.

Section: Discussion Of Experimental Resultsmentioning

confidence: 99%

“…(7) are determined by the behavior of the amplitude-fluctuation variance which, in turn, is directly related to the behavior of the variance (∆N 1 ) 2 of integral fluctuations in the electron number density for an ionospheric layer with small-scale plasma irregularities [6,7].…”

Section: Discussion Of Experimental Resultsmentioning

confidence: 99%

Fractal structure of artificial ionospheric turbulence

Myasnikov

et al. 2008

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“…(1) and (2) yields information on the multifractal spectrum of the amplitude fluctuations of the received signal [1,2].…”

Section: Multifractal Analysis Of Received Signals and The Local Strumentioning

confidence: 99%

“…The problem of the local structure of developed ionospheric turbulence, which is closely related to the problem of fractal properties of small-scale ionospheric irregularities, was discussed in [1,2]. However, the studies performed in those works are actually restricted to analyzing the behavior of only one component of the multifractal spectrum of fluctuations of the received-signal amplitude and, correspondingly, one component of the spectrum of fluctuations of the electron number density in the small-scale irregularities of the ionospheric plasma.…”

Section: Introductionmentioning

confidence: 99%

“…However, the studies performed in those works are actually restricted to analyzing the behavior of only one component of the multifractal spectrum of fluctuations of the received-signal amplitude and, correspondingly, one component of the spectrum of fluctuations of the electron number density in the small-scale irregularities of the ionospheric plasma. Namely, in [1,2], the multifractal analysis of fluctuations of the amplitude A(t) of signals during their ground-based reception after the sounding of the inhomogeneous ionosphere from the Earth's orbital satellite was used only for estimating the spectral characteristics of the local structure of small-scale ionospheric turbulence (SSIT), which correspond to the second-order structural function for small-scale fluctuations of the electron number density of the ionospheric plasma (see [1,2] for more detail). At the same time, generally speaking, the multifractal analysis of the received satellite signals allows us to obtain more detailed information on the multipower spectrum of small-scale ionospheric turbulence.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Multipower spectrum of small-scale ionospheric turbulence

Rakhlin

2009

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UDC 621.371+533.951We consider the problem of diagnostics of the local structure of small-scale ionospheric turbulence using the multifractal analysis of received signals from the Earth's orbital satellites after the radio sounding of the inhomogeneous ionosphere by these signals. In particular, it is shown that analysis of the multifractal structure of the received-signal amplitude records by the method of multidimensional structural functions allows one to determine the indices of the multipower local spectra of the small-scale ionospheric turbulence, which are inherent in it due to the nonuniform spatial distribution of small-scale fluctuations of the electron number density. It is noted that information on the multipower spectrum of small-scale ionospheric turbulence is not available for the conventional radio scintillation method based on the classical spectral analysis of received signals during the remote radio sounding of the ionosphere. At the same time, the method of multidimensional structural functions is efficient under conditions of actual nonstationarity of the process of scattering of the HF radio waves by the randomly inhomogeneous ionospheric plasma. The method of multidimensional structural functions is used for the multifractal processing of received signals of orbital satellites during special experiments on radio sounding of the midlatitude ionosphere under natural conditions and its modification by high-power HF radio waves. First data on the indices of the multipower local spectra of small-scale ionospheric turbulence are obtained.

Some features of the fractal structure of the developed small-scale ionospheric turbulence

Rakhlin

2008

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We present the results of the first studies of the fractal structure of the developed small-scale ionospheric turbulence (SSIT) during special experiments on radio-raying of the midlatitude ionosphere by signals from orbital satellites in [2005][2006]. It is established that under conditions of developed turbulence, typical values of the fractal dimension of the space occupied by natural SSIT inhomogeneities are, as a rule, close to the topological dimension of their embedding space, and the true values of the spectral index of isotropic SSIT only slightly differ from the corresponding generally accepted nominal values in the embedding space. Nevertheless, even small differences in the mentioned parameters detected in the experiment witness a sharply nonuniform distribution of the local fractal structures of the developed SSIT in space. We propose a stochastic model of the nonstationary process for fast amplitude fluctuations of signals during their propagation in the ionosphere with nonuniform spatial distribution of small-scale electron-density fluctuations. Eventually, namely this nonuniform distribution of small-scale electron-density fluctuations leads to the specific multifractal structure of the amplitude records of received signals.