Radio Science

Statistical characterizations of equatorial scintillation in the Asian region

Authors

  • D. J. Fang,

  • C. H. Liu


Abstract

The morphological aspect of gigahertz equatorial scintillations in the Asian region has been reported. As a follow-up, this paper studies the statistical aspect of equatorial scintillations in the same region. Power spectra of prominent scintillation events collected over a 16-month period during the solar maximum years in sunspot cycle 21 were analyzed. The slope ν of the spectrum at the high-frequency end was analyzed with respect to the strength of scintillation as indicated by scintillation index S4. The values of S4 were compared with theoretical calculations based on either phase screen formulation or Rytov approximation. These comparisons were used to assess ionospheric parameters such as the height and thickness of the irregularities layers, rms fluctuation of the total electron content, and the axial ratio of the irregularities. Autocorrelation calculation provided a characteristic coherent interval τ. The study suggests that equatorial ionospheric irregularities in the F region, with subkilometer sizes in the evening hours after local sunset, are the main cause of the gigahertz scintillations observed. The spectra of the irregularities appear to be the power law type, with spectral indices p that generally have values greater than 4. The characterizations of S4, ν, and τ for both the Pacific and Indian Ocean region links provide an important basis for improved modeling of ionospheric scintillation phenomena in the Asian region.

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