Bay-Shaped Variations in the Geomagnetic Field that Accompanied the Catastrophic Explosion of the Tonga Volcano on January 15, 2022

The Tonga volcano is among the five most powerful volcanoes in the world. The explosion of the Tonga volcano on January 15, 2022, was unique. It has led to disturbances in the lithosphere, World Ocean, atmosphere, ionosphere, magnetosphere, and all geophysical fields. A number of studies have been devoted to the disturbance of the Earth’s magnetic field. The transport of magnetic field disturbances by atmospheric gravity waves and tsunamis, disturbances in magnetically conjugated regions due to acoustic resonance, the effect on the equatorial electrojet, etc., have been studied. This is far from the end of the variety of magnetic effects of the Tonga volcano. This study is aimed at describing the results of the analysis of global bay disturbances in the geomagnetic field observed after the Tonga volcano explosion on January 15, 2022. The results of measuring the temporal variations in the level of the X, Y, and Z components by the INTERMAGNET world network of stations are used as initial data. The analysis of the magnetic data is preceded by an analysis of space weather conditions. A preliminary analysis of temporal variations in the level of the X-, Y-, and Z-components indicates that these variations on the reference days are smoother than on January 15, 2022. An analysis of the temporal variations in the level of the X-, Y-, and Z-components of the geomagnetic field and a statistical analysis of the disturbance parameters have shown the following. Bay disturbances of all components of the geomagnetic field are observed with a time delay that varies depending on the distance to the volcano from several tens of minutes to 100–200 min. The magnitude of the effect varies from approximately 10 to approximately 60 nT. The largest disturbances occur in the Y component. The delay time and duration of disturbances increase with an increase in the distance from the volcano, while their amplitude, on the contrary, decreases. The speed of propagation of bay disturbances is close to the speed of the blast wave. Bay disturbances are weakly expressed or completely absent on the night side of the planet. It is substantiated that bay disturbances are closely related to the occurrence of an ionospheric hole under the action of a blast wave from the volcano. The results of estimates of bay disturbances are in good agreement with the observation results.