A large explosion released a significant amount of energy into the Earth's upper atmosphere in Beirut on 4 Aug 2020, generating traveling ionospheric disturbances (TIDs). These TIDs were observed in previous work using GPS total electron content measurements around Beirut. Here, we used measurements from the Defense Meteorological Satellite Program and ionosondes in the Mediterranean to show that the TIDs from the Beirut explosion were able to reach greater distances than previously reported.

The receiver at the Harbin Engineering University and eight surrounding HF broadcast stations ~1000 km observed the response in the ionospheric electron density to the activity of Typhoon Kong-rey (30 September–6 October 2018). On 1–2 and 5–6 October 2018, the 20 min to 60 min period quasi-sinusoidal variations in the electron density with an amplitude of 0.4 % to 6 % resulted in 0.1 Hz to 0.5 Hz amplitude Doppler shift variations, a factor of 2–3 increase as compared to a quiet time reference.

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 %).

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.