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Zusammenfassung:
Infrasound is defined as pressure fluctuations with frequencies between acoustic cut-off (5 min) and human-hearing frequency threshold of sound (16 Hz). At low frequencies, infrasonic waves can travel long distances, ranging from hundreds to several thousands of kilometres. The dynamics in the middle atmosphere mainly control the presence of atmospheric waveguides where energy transmission loss is low. These properties are utilized to record atmospheric explosions at highly sensitive pressure sensors (micro-barometers). A global network of 60 infrasound stations was designed as part of the International Monitoring System (IMS) dedicated to monitoring compliance with the Comprehensive Nuclear-Test-Ban Treaty. IMS infrasound stations can record small pressure fluctuations of a few millipascals, which can originate from numerous atmospheric infrasound sources. In this study, the capability of IMS infrasound arrays for capturing a broad spectrum of atmospheric wave phenomena – from atmospheric tides over Lamb waves to mountain-associated waves – is highlighted. Also, the interaction of ocean waves produces quasi-continuous infrasound, so-called microbaroms. Since winds and the temperature in the middle atmosphere determine the long-range detectability of such signals, it has been demonstrated that infrasonic signatures can be used for probing the middle atmosphere dynamics and assessing atmospheric circulation models. Therefore, the potential of infrasound for assimilation in weather or climate models was proposed, e.g. by the Atmospheric Dynamics Research InfraStructure (ARISE) project. For opening the IMS network for such purposes or, e.g., early warning systems on volcanic eruptions, this study highlights open-access data products derived from infrasound detections.
