Results of studying different-scale ionospheric irregularities on the basis of multi-instrumental data, obtained in the East Siberian region of Russia during the geomagnetic storm of May 27–28, 2017, are presented. Spatial inhomogeneities of electron density in the ionosphere were observed through data from ground-based receivers of signals of global navigational satellite systems and on the basis of direct measurements of electron density in low-orbit satellites. An intense radio aurora was seen in UHF radar data just after the initial phase of geomagnetic storm. At the same time, we recorded fluctuations of the total electron content from data of GPS receivers and the presence of E-layer irregularities by data of the ionosonde in Norilsk. The time of irregularity recording by different instruments is consistent with the spatiotemporal changes in field-aligned currents of the second zone, obtained from data of AMPERE low-orbit satellite system.

The author's name should read H. Schmidt instead of Kh. Shmidt

The maximum electron density of the F2 layer N(m)F2 relative to the solar activity level is studied. The optimal period for averaging the solar activity index F-10.7 is found, which gives on average the lowest error and the highest correlation coefficient (in space and in time) for describing the linear dependence of N(m)F2 vs. F-10.7. This result depends substantially on the duration of N(m)F2 data storage selected.

The author’s name should read H. Schmidt instead of Kh. Shmidt

Programs designed for automatic collection and processing of data on the ionospheric F2-layer parameters obtained by the radio occultation method are described. The programs developed make it possible to analyze the dependence of the parameters h m F2, foF2, and N m F2 on the level of solar activity with a given temporal and spatial resolution, which is important in solving scientific and applied problems. Global maps of the distribution of the maximum electron density of the F2-layer are presented for different seasons and times (UT and LT). The diurnal and seasonal variations of the normalized parameter N m F2 are compared with data calculated by empirical and numerical ionospheric models and with ionosonde data. The results calculated in this study reproduce all existing ionospheric anomalies and demonstrate a qualitative agreement with the data obtained by different methods. This indicates that radio occultation observation data can be efficiently used in theoretical research and empirical modeling of the ionosphere.