STP002

This abstract presents the results of radio observations of ionospheric disturbances associated with the fall of the meteoroid (unique in its initial energy of 173 kt TNT equivalent) off the east coast of the Kamchatka Peninsula on 18 December 2018. The observations of the ionospheric response to the fall and airburst of the Kamchatka meteoroid have been taken using the multipath radio system for probing the ionosphere at oblique incidence. The development of the system, produced by  V. N. Karazin Kharkiv National University and Harbin Engineering University specialists and situated at the Harbin Engineering University campus (45.78°N, 126.68°E), involves the software-defined radio technology. Broadcast stations, located in the People´s Republic of China, Japan, Russia, and Mongolia, are used as transmitters. The distance from the terminal detonation point to the middle of the propagation path varied from ~2,750 km to ~4,250 km, and the frequency of the sounding signals from 5,000 MHz to 9,750 MHz. The measurements have been taken along fourteen propagation paths; however, the mode of operation of only six transmitters was found to be suitable for further analysis. The temporal variations in the Doppler spectra, the Doppler shift of frequency and in the signal amplitude measured on a relative scale, have been observed over each propagation path and subsequently analyzed. The main results are as follows. The ionospheric disturbances following the Kamchatka meteoroid entry and explosion have been detected in the temporal variations in the Doppler spectra and signal amplitudes observed over six oblique propagation paths. The possible disturbances have 2 – 3 groups of time delays. Depending on the distance between the terminal detonation point and the propagation path midpoint, these time delays fall into the 24 – 43-min, 93 – 136-min and 141 – 183-min time intervals, corresponding to the apparent speeds of 1.9 – 2.9 km/s, 620 – 770 m/s and 310 – 500 m/s, respectively. The disturbances with the apparent speeds of hundreds of meters per second and periods of about 10 – 15 min are transported by atmospheric gravity waves. The disturbances propagating with the 1.9 – 2.9-km/s apparent speeds could be caused by ionospheric processes due to the seismic waves generated by the meteoroid explosion.