Kamchatka Meteoroid Effects in the Geomagnetic Field

The data acquired at ten geomagnetic observatories (Paratunka, Magadan, Yakutsk, and Khabarovsk (the Russian Federation); Memambetsu, Kanoya, and Kakioka (Japan); Cheongyang (Republic of Korea); Shumagin and College (USA)) during the Kamchatka meteoroid event of December 18, 2018, and on the reference days of December 17 and 19, 2018, have been used to analyze temporal variations in the geomagnetic field components. The distance r from the observatories to the site of explosive energy release by the meteoroid varied from 1.001 to 4.247 Mm. The passage of the Kamchatka meteoroid through the magnetosphere and atmosphere was accompanied by variations mainly in the H geomagnetic field component. The magnetic effect from the magnetosphere was observed to occur twice, 51 and 28 min prior to the meteoroid explosion; the amplitude of the disturbances in the geomagnetic field did not exceed 0.2–1 nT, and the durations were observed to be approximately 20 and 10 min, respectively. Alternating peaks in the level of the H component were observed to lag behind the meteoroid explosion by 8 to 13 min for r from 1.001 to 4.247 Mm. The amplitude of the oscillations varied with increasing r from ~0.5 to ~0.1 nT, while the duration of the magnetic effect from the ionosphere varied in the 16–25-min range for all distances. The apparent speed of propagation in this group of disturbances that were of MHD nature was observed to be approximately 10 km/s. In the second group of disturbances, the time lag increased with increasing distance within the distance range mentioned above from 56 to 218 min. The duration of the disturbance was approximately 16–65 min, the apparent speed was 336 m/s, and the period was 5–10 min. This disturbance in the magnetic field was caused by an atmospheric gravity wave propagating from the meteoroid explosion. The theoretical models for the magnetic effects observed are presented and theoretical estimates are performed. The observations are in agreement with the estimates.