ALBERT

Description: In 2022, we witnessed two extraordinary geophysical events. The 15 January 2022 eruption of the Hunga-Tonga volcano was the largest explosion in the atmosphere since the 1883 eruption of the Krakatoa volcano. Then, in the second half of the year, an exceptionally bright and long-lasting Gamma Ray Burst (GRB 221009A) event hit Earth on 9 October 2022, causing significant perturbations in the ionosphere. In this contribution, we discuss the impact of these two extraordinary events on Schumann resonances (SRs), which are the global electromagnetic (EM) resonances maintained by lightning activity in the cavity formed by the ground and the lower ionosphere. While the extreme lightning activity associated with the Hunga-Tonga eruption represented a unique point-like excitation source for the SRs, the GRB event may have changed the propagation conditions of EM waves traveling in the Earth-ionosphere waveguide. The impact of the Hunga-Tonga eruption is evident all over the world in the intensification of SRs. We show what information can be obtained from SR on the volcanic lightning activity and summarize our efforts to model the SR observations. On the other hand, the impact of the GRB event on SR is much less obvious, with only a slight increase in the spectral energy content observed at certain SR stations. We present a detailed analysis of global lightning activity in the hour of the GRB event to assess whether the observed small changes are indeed related to that event.