Diurnal variations in the spectrum of lower-ionosphere plasma irregularities

We examined the variations caused in the spectrum of lower-ionosphere plasma irregularities by diurnal changes of ionospheric parameters. We demonstrate that at a height of 95 km, where the irregularities arise due to the turbulence of the neutral atmosphere, the expected level of plasma irregularity fluctuations at a constant turbulent mixing intensity is smaller in the daytime than at night. The one-dimensional spectrum which can be measured in experiments also changes, namely, the spectrum slope is greater at night.