Multi‐Position Facility for HF Doppler Sounding of Ionospheric Inhomogeneities in Ukraine

This paper describes a system for multi‐position Doppler ionosphere sounding implemented at the beginning of 2018 in the Kharkiv region of Ukraine, the data processing technique and initial results of data analysis. The system comprises a high frequency (HF) transmitter and three receiving sites making almost a right triangle with catheti of 32.8 and 58 km. The transmitter continuously emitting a monochromatic signal of a ∼20 W power at a frequency in most cases slightly lower than foF2 is located in the city of Kharkiv. The foF2 value was permanently controlled by the ionosonde installed in about 45 km from the transmitter. We report and discuss the initial results of traveling ionospheric disturbances (TIDs) observations for three years since January 2018 until December 2020. Statistical distributions of the frequency of appearance, periods, horizontal speeds, and propagation directions of TIDs are presented. The range of their most probable wavelengths is from 120 to 260 km, while their propagation velocities are from 80 to 220 m/s. The preferred direction of the TID propagation changes during the daytime and shows a tendency to rotate clockwise in azimuth. Notably, such regular long‐term measurements in the Eastern Europe have been carried out for the first time. Key Points We describe a novel multi‐position high frequency Doppler facility in Ukraine and data processing technique capable of exploring the traveling ionospheric disturbances (TID) parameters Variations of the Doppler frequency shift from each of three sites revealed the salient TID characteristics in several case studies Statistical distributions of the appearance frequency, periods, horizontal speeds, and directions of TIDs during a few years are presented