Contribution of infrasound monitoring for atmospheric remote sensing

Abstract

A number of International Monitoring System (IMS) type infrasound stations are now operating for many years. Continuous automatic processing of the data is being performed in the [0.02-4] Hz frequency band in order to detect and characterize coherent infrasonic waves. A large number of detections are associated with natural phenomena. Ocean wave interactions are quasi-permanent sources of infrasonic waves detected on a global scale. Their monitoring reveals clear periodic trends in the detected bearings and signal amplitude, providing further confirmation that long-range propagation strongly depends on the atmospheric conditions. Ocean swells are then valuable sources for global atmospheric monitoring since pressure waves can be generated continuously over long duration, allowing investigations in the seasonal and diurnal fluctuations of the atmosphere. Signals from volcanic eruptions also offer a unique opportunity for atmospheric studies. At large propagation ranges from volcanoes, infrasound measurements can be used as input of inversion procedures to delineate the vertical structure of the wind in a range of altitude where ground-based or satellite measurements are rare. Such studies provide new insights on quantitative relationships between infrasonic observables and atmospheric specifications. © 2009 Springer Science+Business Media B.V.