Small-scale turbulence in the upper ionosphere

We discuss the results of studies of natural and artificial small-scale turbulence in the upper ionosphere. The first data on the spectrum of sizes of irregularities at altitudes 240–340 km were obtained in the 1970s by the method of aspect scattering of radio waves and the method of radio-raying of the ionosphere by radio signals from Earth-orbiting satellites. New data on the irregularities with a size of about 20 m were obtained by the method of backscattering of radio waves in the period 2009–2011 using the “Sura” facility radar. The radar measurements allow one to complement the empirical model of irregularities in the F layer of the ionosphere.