Mid-latitude quasi-periodic scintillations of satellite beacon signals

Abstract

Simultaneous observations of amplitude fluctuations at two separated stations and of the relative phase of the arriving signals are used to study quasi-periodic scintillations of the kind that are sometimes called ‘ringing irregularities’. Since one set of measurements is sufficient to locate the irregularity it is possible to assess the utility of the simple model proposed by Elkins and Slack by using it in a computer simulation to predict the temporal behaviour of the other observed quantities. The resulting agreement leaves no doubt that scintillations arise in the ionosphere by a mechanism having the gross features of the one suggested, although the additional redundant observations permits the derivation of information about the ionospheric irregularities not encompassed by the Elkins and Slack model. This simple geometric model which assumes specular reflection is extremely useful and the more complete scattering analysis is needed only where detailed information about the irregularity is required. Evidence is also presented for the occasional occurrence of large angle scattering from ionospheric irregularities.