Observation & study of a kind of low-frequency atmospheric infrasonic waves

A kind of low-frequency atmospheric infrasonic waves has been studied.Such infrasonic waves have been observed by a wide-spread sensor network array consisting of broadband infrasound microphones for about 5 years. According to continuous observations and statistic analyses,it could be possible that such kind of infrasound is closely associated with some natural events.The waveforms,spectra,time-frequency charts and correlations among sensors of these infrasonic waves have been analyzed.The results show that these waves occur either in one group or intermittently in several groups with frequencies in a range of 0.001~0.02 Hz and amplitudes in a range of 50~200 Pa.Besides, such infrasonic waves were observed previous to several strong earthquakes,such as Yutian earthquake on Mar.20th 2008,Wenchuan earthquake on May 12th 2008,Shan-Gan-Chuan border earthquake on Oct.29th 2009,and so on.The results provided in this paper may propel the study of atmospheric infrasonic waves and the correlations with natural events,especially with earthquakes.