Global Monitoring and Characterization of Infrasound Signatures by Large Fireballs

Abstract

Large meteoroids can be registered in infrasound recordings during their entry into the Earth's atmosphere. A comprehensive study of 10 large fireball events of the years 2018 and 2019 highlights their detection and characterization using global infrasound arrays of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The study focuses on the observation and event analysis of the fireballs to estimate their respective location, yield, trajectory, and entry behavior. Signal characteristics are derived by applying the Progressive Multi-Channel Correlation method as an array technique. The comparison of the events with a NASA reference database as well as the application of atmospheric propagation modeling allows to draw conclusions about infrasound-based detection capability, localization accuracy, yield estimation, and source characterization. The infrasound technique provides a time-and location-independent remote monitoring opportunity of impacting near-Earth objects (NEOs), either independent or complementary to other fireball observation methods. Additionally, insights about the detection and localization capability of IMS infrasound stations can be gained from using large fireballs as reference events, being of importance for the continuous monitoring and verification of atmospheric explosions in a CTBT context.Atmosphere 2020, 11, 83 2 of 16 of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) [11]. Six infrasound arrays observed the 2004 Antarctica, 2004 Indian Ocean, and 2006 Egypt bolides with 10-20 kilotons of trinitrotoluene (kt TNT) equivalent yield each [12]. About 20 infrasound arrays observed the 2009 Sulawesi and the 2010 North Pacific (super-)bolides with 30-50 kt yield each [13,14]. Finally, 32 signal arrivals from at least 20 infrasound arrays also along long orthodrome paths and after complete circumnavigations of the Earth were recorded for the 2013 Chelyabinsk superbolide with 500 kt yield [15,16]. Together with the 173 kt Bering Sea fireball of December 2018, investigated in this study, these infrasound studies cover the four largest fireball events of the last decades.Large fireballs over populated areas can cause a lot of public attention. In the age of Social Media a huge amount of information is shared via various social media platforms as soon as an event happens. NEMO, the NEar real-time MOnitoring system for bright fireballs [17,18], is a project established to collect and combine information about such events in near real-time. For most fireball events it is possible to extract the date, time, and a rough location of an event from information shared only via Social Media. Using infrasound array data, it is furthermore possible to compute the yield and size of the entering object using the energy derived in the infrasound signals' dominant period band [19].Additional information about the object is usually available from other sources. One fast source is the American Meteor Society/International Meteor Organization (AMS/IMO) database for witnes...

1001 Rocket Launches for Space Missions and Their Infrasonic Signature

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