Measurement of phase variance and autocorrelation during radio-star visibility fades

Quantitative results for 49 visibility fades observed from College, Alaska, during 1965 are presented. A majority of the fades revealed ionospheric optical depths in excess of unity at 68 MHz. Optical depth is numerically equal to mean‐square fluctuation in radio‐frequency phase across a plane at the base of the scattering region; thus, the fades often were characterized by rms phase deviations in excess of one radian at 68 MHz. The wavefront phase structure immediately after scattering was found to have scales in the range of tens and hundreds of meters. The observations usually were not consistent with the demands of a Gaussian autocorrelation function, as is commonly assumed. Rather, the perturbed wavefronts displayed evidence of quasi‐periodic structure in the observed dimensional range.

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Commission 3: Progress in Ionospheric Radio

Villard¹,

Aarons²,

Bibl³

et al. 1969

Radio Science

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The major advances in our understanding of the morphology of the D region in the last three years have come about through the application of rocket techniques. A series of rocket measurements carried out at Wallops Island [Mechtly and Smith, 1968a] at different seasons but at roughly the same solar zenith angle have shown the principal features of the seasonal variation in the electron density profile between 50 and 100 km. It appears that electron densities are lower by a factor of about 3 below 82 km on ‘normal’ winter days as compared with summer days for a solar zenith angle of 60°. The anomalous winter days of high absorption have been the subject of a separate rocket investigation [Sechrist et al., 1969], which has shown that the electron density profile is remarkably similar to that of a normal summer day and that in at least one case was associated with a pronounced temperature inversion near 70 km.

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Measurement of phase variance and autocorrelation during radio-star visibility fades

Cited by 4 publications

References 10 publications

On radio-star visibility fades and the aurora

On radio-star visibility fades and the aurora

Radio-star visibility fades in Alaska near Solar Minimum

Commission 3: Progress in Ionospheric Radio

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