FORECASTING THE CRITICAL FREQUENCIES OF THE IONOSPHERE OVER BULGARIA IN 2022

The present study aims to illustrate the work in real time and in the conditions of geomagnetic storm of the developed empirical model for forecasting the critical frequencies of the ionosphere for the territory of Bulgaria. The task of creating a methodology for determining the critical frequencies is the main activity after the completion of the work of the “Plana” ionospheric station for the vertical sounding. For this purpose, a team from Department of Geophysics at the National Institute of Geophysics, Geodesy and Geography (NIGGG) – Bulgarian Academy of Sciences developed a method for determining the critical frequencies of the ionosphere based on Total Electron Content (TEC) data. The methodology allows continuing the preparation and publication of forecasts for the radio wave propagation on the territory of Bulgaria, which are used by governmental institutions and are freely available to radio amateurs through the website of the NIGGG. In the present work, a comparison is made between the critical frequencies of the ionosphere obtained by TEC for Bulgaria and the data from the vertical sounding at Rome station (RO041, 41.9°N, 12.5°E). The choice of this ionospheric station is related to the fact that this station is located at the geographic latitude coinciding with the latitude of Sofia, which suggests similar characteristics of the ionosphere. The difference in local time is also reported. The comparison between the data of the Rome ionospheric station in and those determined according to the TEC data for Bulgaria shows that the deviations are close to those obtained in the comparison with the data of Plana ionospheric station for the period 1995-2014. The described results show that the created empirical model for reconstruction of the critical frequencies by TEC data on the basis of a previous period allows predicting the current state of the ionosphere even in the conditions of geomagnetic disturbances.