OSCILLATIONS IN IONOSPHERIC VIRTUAL HEIGHT, ECHO AMPLITUDE AND DOPPLER VELOCITY - THEORY AND OBSERVATIONS

Applying perturbation theory to the Appelton-Hartree formulas, a detai led derivation of ionospheric parameters for ionospherically reflected echoes shows that: 1) oscillations of Doppler velocity, virtual heigh t and echo amplitude have the same power spectrum; 2) the temporal var iations in Doppler velocity lead or lag those in phase height by 90-de grees; and 3) the phase difference between the variations in echo ampl itude and those in virtual height is either 0-degrees or 180-degrees. The analysis of experimental data obtained using a digital HF ionosond e (Dynasonde) confirms that oscillations in Doppler velocity, virtual height and echo amplitude have nearly identical power spectra and the phase difference is in good agreement with the derived theory. It is c oncluded that several different parameters measured by or derived from ionospheric soundings can be used to study ionospheric variations.