Ionospheric positive storm phase on 18 December 2019 observed by the Kharkiv incoherent scatter radar

The aim of the work is experimental studies of variations in ionospheric plasma parameters over Ukraine during the very moderate magnetic storm on December 18, 2019 ($K_{p} = 4$). The ionosphere response over Kharkiv to the magnetic storm on December 18, 2019 was analyzed. It was established that a very moderate magnetic storm caused noticeable changes in ionospheric plasma parameters in the entire range of studied altitudes. An increase in the $N_{m}\text{F2}$ (up to by a factor of 2.8) were accompanied by a chain of changes in the variations of the main parameters of the ionospheric plasma. The mechanisms are considered to explain generation of the positive storm.