Effects of universal time in the polar ionosphere.

Reference is made to earlier studies in which an analysis of the daily variance of f0F2 at antarctic stations has suggested the presence of UT control over the polar ionosphere. In particular, it has been shown that UT control produces a second maximum on the f0F2 daily variance curves that is different in amplitude and in time of occurrence from the principal meridional maximum. In the study reported here, the effects of UT control over the variance of the spatial-temporal distribution of electron concentration in the polar ionosphere have been investigated by vertical sounding and incoherent scattering, by direct satellite measurements, and by mathematical modeling. Experimental data are presented and compared with model predictions.