Power spectra of ionospheric scintillations

Journal Article · Tue Jan 01 04:00:00 EST 1974 · J. Atmos. Terrest. Phys., v. 36, no. 1, pp. 113-133

DOI:https://doi.org/10.1016/0021-9169(74)90071-3· OSTI ID:4378232

Singleton, D G

The diffraction theory of interplanetary scintillations, which allows a connection to be established between the spatial spectrum of electron-density fluctuations in the irregular medium and the power spectrum of intensity scintillations observed on the ground, is reviewed and applied to the case of the ionosphere. Expressions are found for the Fourier and Bessel spectra of the intensity scintillations for both Gaussian and power-law ionospheric irregularities. These are employed to interpret experimental Fourier and Bessel spectra observed at Hamilton, Massachusetts. It is found that 80 per cent of the Bessel spectra but only 10 per cent of the Fourier spectra are modulated in the way predicated by the theory for various diffraction pattern configurations. This leads to the conclusion that the diffraction pattern on the ground is only slightly anisotropic, the extent of the anisotropy being larger to the north at low elevations than overhead. Further, it is shown that this result is consistent with the interpretation of recent scintillation index observations in ternns of irregularities which are elongated along the magnetic field and, to a lesser extent, normal to the magnetic-meridian plane. The scintillation spectra are also consistent with a spatial spectrum of electron-density fluctuations in the ionosphere which is power law rather than Gaussian in form. The implication of this failure of the Gaussian form to diffraction theory is discussed briefiy. (auth)

• Research Organization: Air Force Cambridge Research Labs., Bedford, MA
• NSA Number: NSA-29-013699
• OSTI ID: 4378232
• Journal Information: J. Atmos. Terrest. Phys., v. 36, no. 1, pp. 113-133, Journal Name: J. Atmos. Terrest. Phys., v. 36, no. 1, pp. 113-133; ISSN JATPA
• Country of Publication: United Kingdom
• Language: English

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