Characteristics of Infrasonic Signals Generated by the Lipetsk Meteoroid: Statistical Analysis
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AMICS AND PHYSICS OF BODIES OF THE SOLAR SYSTEM
Characteristics of Infrasonic Signals Generated by the Lipetsk Meteoroid: Statistical Analysis L. F. Chernogora, * and M. B. Sheveleva aKarazin
Kharkiv National University, Kharkiv, 61022 Ukraine *e-mail: [email protected]
Received February 21, 2020; revised February 21, 2020; accepted April 13, 2020
Abstract—The purpose of this paper is to construct basic correlation diagrams and plot the respective 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: 14.4 km/s speed, approximately 113 t mass, approximately 4 m size, and approximately 2.8 kt TNT kinetic energy. 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 the 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 at approximately 302 m/s. 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 versus sine of the back-azimuth angle of arrival shows that the corrected value of the celerity is approximately 300 m/s, and the mean of the troposphere-stratosphere wind is approximately 25–31 m/s. Analysis of the correlation 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: Lipetsk meteoroid, infrasound, signal parameters, regression, correlation diagrams DOI: 10.3103/S0884591320040030
INTRODUCTION The intrusion of any sufficiently large cosmic body into the Earth’s atmosphere and the physical effects caused by it deserve careful study. A recent event of this kind was the passage and explosion of the Lipetsk meteoroid [9]. This cosmic body entered the Earth’s atmosphere near the city
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