The solar eclipse of 5–6 January 2019 perturbed the ionospheric electron density, N, observed with the receiver at the Harbin Engineering University and 14 HF broadcasting stations ~1 000 km around. It was accompanied by ±1.5 Hz Doppler-spectrum broadening, ±0.5 Hz Doppler shift, f_D, variations, 15 min period variations in f_D caused by 1.6–2.4 % perturbations in N, and period changes of 4–5 min in f_D caused by 0.2–0.3 % disturbances in N. The decrease in N attained ~15 % (vs. modeled 16 %).

The Super Typhoon Kong-Rey maximum energy release is clearly observed in the 2,800–3,300 km range. The quasi-sinusoidal perturbations in the electron density exhibit variability in the ~20–120 min period range, within which the amplitude of the electron density increases from a few to several tens of per cent, and which means that they are due to atmospheric gravity waves excited by the typhoon. The dusk terminator and super typhoon act synergistically to amplify the ionospheric response.

In this work, we use the Disturbance Ionosphere indeX (DIX) to study equatorial plasma bubble (EPB) events over the Brazilian equatorial and low latitudes. Our results showed that the DIX detected EPB disturbances in terms of their intensity and occurrence times. Therefore, these responses agreed with the ionosphere behavior before, during, and after the studied EPBs. Finally, these disturbances tended to be higher (lower) in high (low) solar activity.

We combined the observed diurnal VLF amplitude variation in the D region with standard measurements of the E and F regions to perform a diagnostic investigation of coupled geomagnetic storm effects in order to understand the observed storm-induced variations in VLF narrowband based on state and responses of the ionosphere. The dayside VLF amplitude showed a tendency for attenuation following geomagnetic storms, and the h’E and h’F variations confirmed strong storm response over the signal paths.

The 30 August–2 September 2019 geospace storm and its influence on the characteristics of high frequency radio waves over the People's Republic of China have been analyzed. The geospace storm was weak, the magnetic storm was moderate, and the ionospheric storm was moderate to strongly negative, which manifested itself by the reduction in the ionospheric F-region electron density. Appreciable disturbances were also observed to occur in the ionospheric E-region and possibly in the E_s layer.