ИСТИНА

The study is based on the data of the rapid-run ionosonde at the Sodankylä Geophysical Observatory at auroral latitude which routinely performs one-minute sounding since 2007. The ionospheric oscillations corresponding to Pc5 geomagnetic pulsations were found in variations of the virtual height of the F layer and the intensity of ionosonde reflections from E and F layers. Besides that, pulsations of intensity of reflection from E and F layers typically contain essential second harmonic. Our study has shown that some frequencies (and, probably, spatial scales) are persistently highlighted in the ionospheric turbulence which suggests that additional process apart from turbulent cascade is contributing to the observed temporal variability. The ionosphere “2-nd harmonic" oscillations are not related to accompanying geomagnetic Pc5 pulsations or cosmic noise absorption. During many events ionospheric quasiperiodic fluctuations with frequencies in the band ~3-5 mHz are observed without any accompanying geomagnetic ULF activity. The ionosonde observations confirmed the persistent occurrence of quasi-periodic ionospheric inhomogeneities found in Pc5 band during SuperDARN observations.