1987年9月23日日环食所产生的大气内重力波

在日食期间,月影以超声速移过地球大气而使局部大气冷却。Chimonas和Hines认为大气冷却的结果产生激波,诱发大气重力波。这时在电离层中可检测到TID而在地面上可检测到大气压力变化。虽然在电离层中这种重力波信号很弱,但仍可检测到。地面压力变化发生在日食附近地区,甚至离主食带相当远的地方也可以测到。本文报告了在中国首次直接观测日环食引起地面压力波的检测结果。1987年9月23日日环食期间,位于环食带的乌鲁木齐,太原,徐州,苏州及位于偏食带的北京和贵阳共六个次声观测站用电容式微气压计在我国首次探测到日环食产生的声重力波,其周期为10—60min,振幅为7—20Pa(峰-峰值)。动态谱分析的结果表明,各地的重力波周期都有连续的谱分布,其主周期为40min。此外,各地记录到出现时间不同而周期更长的波,对这些结果本文作了初步计论。

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.