The use of infrasound to monitor the atmosphere has, like infrasound itself, gone largely unheard of through the years. But it has many applications, and it is about time that a book is being devoted to this fascinating subject. Our own involvement with infrasound occurred as graduate students of Prof. William Donn, who had established an infrasound array at the Lamont-Doherty Geological Observatory (now the Lamont-Doherty Earth Observatory) of Columbia University. It was a natural outgrowth of another major activity at Lamont, using seismic waves to explore the Earth's interior. Both the atmosphere and the solid Earth feature velocity (seismic or acoustic) gradients in the vertical which act to refract the respective waves. The refraction in turn allows one to calculate the respective background structure in these mediums, indirectly exploring locations that are hard to observe otherwise. Monitoring these signals also allows one to discover various phenomena, both natural and man-made (some of which have military applications).
Author Biography
A. Le Pichon (Master Degree in Fundamental Physics. PhD in Acoustics) Since 1998, geophysicist at the French National Data Center (NDC), hosted by CEA/DASE, in charge of Infrasound research activities on topics relevant to Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO): signal processing for automated detection and source location procedures, propagation modeling, methods for source characterization. E. Blanc: Research director at CEA. Main research areas are infrasound and gravity waves, electrodynamical coupling of the atmospheric layers, atmospheric disturbances produced by lightning and sprites. She coordinated international research projects: study of infrasound from strong chemical explosions in USA and in Russia, HF radar observations of the disturbances of the equatorial ionosphere, space observations of lightning and sprite. A. Hauchecorne (Research director at CNRS; since 2005 Director of Aeronomy Service Laboratory):Main research areas are dynamics and climatology of the middle atmosphere; transport and mixing of ozone and minor constituents in the stratosphere; analysis of satellite data analysis and data assimilation in the field of stratospheric chemistry; lidar techniques for the measurement of stratospheric parameters.
