Characteristics of infrasonic signal generated by the Lipetsk meteoroid: statistical analysis

1Chernogor, LF, 1Shevelev, MB
1V.N. Karazin Kharkiv National University, Kharkiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2020, 36(4):58-72
https://doi.org/10.15407/kfnt2020.04.058
Start Page: Dynamics and Physics of Solar System Bodies
Language: Ukrainian
Abstract: 

The purpose of this paper is to construct basic scatter diagrams and plot the corresponding regression functions for the parameters of the infrasonic signals launched by the Lipetsk meteoroid. The celestial body that entered the Earth’s atmosphere at 01:16:20 UT on June 21, 2018 had the following initial parameters: speed 14.4 km/s, mass about 113 t, size about 4 m, and kinetic energy about 2.8 kt TNT. The infrasonic signals generated by the celestial body were observed on a global scale, and they were recorded by the International Monitoring System (IMS) set up by Comprehensive Nuclear-Test-Ban Treaty Organization’s International Monitoring System (CTBTO). For data processing, techniques of mathematical statistics have been invoked. The basic results of the study are as follows. The infrasonic signal exhibits a linear dependence of the infrasonic signal time delay on the horizontal distance from the meteoroid explosion epicenter, and the signal celerity averaged over all propagation paths is estimated to be approximately 304...305 m/s. The infrasonic signal celerity first shows a rapid enough decrease with distance, but over the 4.5...8.66-Mm distance range exhibits fluctuations about the 302 m/s value. The duration of the infrasonic signal shows a linear decrease with distance, and the signal duration dispersion is insignificant in the 5...8 Mm distance range. The mean periods of the infrasonic signal, independent of distance and averaged over various regression functions, are estimated to be 6.28 ± 0.98 s and 6.14 ± 0.76 s. The mean of the initial kinetic energy estimated using the oscillation period of the infrasonic signal is 2.26...2.43 kt TNT, which differs insignificantly from the NASA estimates (2.8 kt TNT). The approximation for the dependence of celerity vs. sine of the back-azimuth angle of arrival shows that the corrected value of the celerity is about 300 m/s, and the mean of the troposphere-stratosphere wind is approximately 25... 31 m/s. Analysis of the scatter diagrams has shown that a steady statistical link exists between the true and observed back-azimuth angles of infrasound sources. It is noted that the level of fluctuations in the azimuth tends to increase with distance.

Keywords: infrasound, Lipetsk meteoroid, regression, scatter diagrams, signal parameters
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