On the atmospheric gravity waves during the 23rd September 1987 annular solar eclipse

During solar eclipse, the shadow of moon moves through the earth atmosphere with supersonic speed. Chimonas and Hines deemed that the shock waves produced by cooling of atmosphere world induce gravity waves, and both TIDs and atmospheric pressure changes can be detected in the ionosphere and on the ground respectively. Although the IGW signals from solar eclipse are usually quite weak, they can still be detected. The pressure changes on ground level occur near the region of eclipse, but can be detected even far beyond the path of eclipse. This article is the first one to report results of detecting pressure waves caused by solar eclipse in China. During the 23rd September 1987 annular solar eclipse, IGWs hape been detected and recorded at infrasound observatories in Ürümqi, Taiyuan, Xuzhou and Suzhou, which are situated within the patk of annular eclipse as well as in Beijing and Guiyang, which are situated beside this path. The signals are detected by microbarometers of condenser microphone type. After analysing waveforms of recorded signals numerically, the wave periods and wave amplitudes determined are within the ranges from 10 to 60 minutes and from 7 to 20 Pascals (peak to peak) respectively. Results from dynamical spectral analyses show that the spectral listributions of all the gravity wave periods from various observatories are continuous and possess a common main period of 40 minutes. Moreover, there are waves with even longer periods in different observatories and their appearance time are quite different.