Abstract

Certain classes of ionospheric motions and irregularities have been explained as manifestations of atmospheric waves propagating to ionospheric heights from below [Hines, I960]. If such a mechanism were operative, one might expect to observe ionization oscillations with preferred periods consistent with theoretically predicted wave reflection, ducting, and viscous damping processes such as have been described for internal gravity waves by Pitteway and Hines [1963] and Friedman [1966]. To examine this possibility, ionospheric motions observed with a vertical-incidence CW Doppler (phasepath) sounder have been analyzed with regard to spectral characteristics and for examples of nearly sinusoidal motions.

A Doppler sounder continuously monitors the motions of a relatively localized region of the ionosphere by recording the frequency variations of stable high-frequency transmissions reflected from the E or F layer. Such variations are due to changes in the total radio phase path caused either by vertical motions of the reflecting layer or by changes in the total electron content below the reflection height. The experimental technique and interpretation of radio-Doppler measurements have been described in detail by Davies et al. [1962] and Davies and Baker [1966], to which the reader unfamiliar with the method is referred.