An attempt to detect atmospheric free oscillations by a new array deployment of micro-barometers

(1)我们将微型气压计系统的10mhz时钟替换为50mhz时钟，以提高分辨率，特别是在更高的频率侧。我们还开发了一种遥测数据传输系统，使我们能够通过手边的PC机检索网络数据。(2)我们在关东-东海地区的14个车站安装了该系统。，目前已进入常规运行。由于系统设计的重大变化，现在可用的数据量没有原先预期的那么大。(3)对各站点气压波动的噪声谱进行了分析，发现了一种奇怪的气声震动行为。我们检测到1-5mHz的航空重力波以60 m/s的速度从西向东传播。(4)总结了2007年初在希腊国际会议上发表的观测结果。(1)建立了一个能解释观测到的固体地球与大气之间自由振荡共振现象的激励模型，并在此基础上估计了大气自由振荡的压力幅值，证明了探测的可行性。(2)分析了IRIS地震记录，表明背景自由振荡的激发源位于太平洋。源头是季节性移动的。源不限于浅海，而应扩展到深海。(3)利用日本倾斜计网络数据检测Love波背景。洛夫波与瑞利波的动能比约为1。来自海洋-大陆边界的背景波最强，其次是深海平面，来自大陆的背景波最弱。(4)建立了一种激励模型，将背景Love波和Rayleigh波归因于亚重力波的地形耦合，这些亚重力波有效地产生作用在假定的海底水平面上的切向应力。

Network Construction(1) We replaced a 10 MHz clock of our micro-barometer system with a 50 MHz clock to increase resolution especially on a higher frequency side. We also developed a telemeter data-transmission system which enabled us to retrieve network data by PC at hand.(2) We installed the system at each of 14 stations of our network in the Kanto-Tokai districts. , which is now in routine operation. The amount of the data now available is not as large as originally anticipated because of the compelling change of the system design.(3) We examined the noise spectrum of air pressure fluctuation at each station and found a strange behavior of aero-acoustic tremor. We detected aero-gravity waves at 1-5mHz propagating from the west to east at a speed of 60 m/s.(4) We summarized the observational results obtained by the beginning of 2007, which were reported at an international conference in Greece.Results from Data Analyses and Theoretical Analyses(1) We developed an excitation model that can explain the observed resonance phenomenon of free oscillations between the solid Earth and the atmosphere, based on which we estimated the pressure amplitudes of atmospheric free oscillations to show that the detection is feasible.(2) We analyzed the IRIS seismograms to show that the excitation source of background free oscillations lies in the Pacific. The source moves seasonally. The sources are not limited to shallow seas but should extend to abyssal planes.(3) We detected background Love waves from tiltmeter network data in Japan. Kinetic energy ratio of Love to Rayleigh waves is approximately one. The background waves are strongest from ocean-continent borders, next from abyssal planes and weakest from continents.(4) We developed an excitation model attributing background Love and Rayleigh waves to topographic coupling of infragravity waves that effectively generates tangential stress acting on the presumed seafloor horizon.