Mountain-Associated Waves and their relation to Orographic Gravity Waves

Kurzfassung

Infrasound covers frequencies of around 10−3 Hz to approximately 20 Hz and can propagate in atmospheric waveguides over long distances as a result of low absorption, depending on the state of the atmosphere. Therefore, infrasound is utilized to detect atmospheric explosions. Following the opening of the Comprehensive Nuclear-Test-Ban Treaty for signature in 1996, the International Monitoring System (IMS) was designed to detect explosions with a minimum yield of one kiloton of TNT equivalent worldwide. Currently 51 out of 60 IMS infrasound stations are recording pressure fluctuations of the order of 10−3 Pa to 10 Pa. In this study, this unique network is used to characterize infrasound signals of so-called Mountain-Associated Waves (MAWs) on a global scale. MAW frequencies range from 0.01 Hz to 0.1 Hz. Previous observations were constrained to regional networks in America and date back to the 1960s and 1970s.