Study of the Spatial and Temporal Distribution of Atmospheric Gravity Waves Using Pressure Data From the Dense USArray Transportable Array

非技术声明国家科学基金会为一个前所未有的观测站提供了资金，用于研究地球内部和大气。USArray可移动阵列是一个拥有400个观测站的观测站，它将宽带地震和大气压力传感器放置在一个笛卡尔网格上，每隔70公里，横跨200万平方公里的区域。这些观测站的地震数据提供了美国大陆地下地球内部的高分辨率图像，而这些观测站的大气数据提供了大气现象的测量结果。在最近由美国国家科学基金会资助的一个项目中，加州大学圣地亚哥分校的研究人员开发了一种检测超长波长压力扰动的方法，并描述了它们是如何穿过TA的。与大气研究人员的讨论证实，在地球表面探测到的这些压力扰动与卫星测量在30-50公里高度探测到的重力波相吻合。在这项研究中，研究人员进一步将卫星观测到的重力波与地面记录的压力干扰进行直接比较，目的是确定这些现象发生的时间和地点。由于重力波在将能量从地球表面附近转移到高层大气中起着很大的作用，因此这项研究有助于了解全球大气环流。技术摘要：美国国家科学基金会EarthScope/USArray可移动阵列（TA）的升级为在每个站点都包含气压传感器，为研究大气现象和大气与固体地球的相互作用开辟了新的途径。这个网络将高质量的压力传感器放置在一个规则的、密集的笛卡尔网格上，横跨大约200万平方公里的区域，这种配置允许对大范围的大气波现象进行定量分析。加州大学圣地亚哥分校的研究小组正在使用新的压力数据来研究TA所跨越的中纬度地区的大气重力波。加州大学圣地亚哥分校的研究小组已经开发出一种技术，可以探测波长大于100公里的重力波，并描述它们在TA中的传播特征，从而定量测量它们的特征（速度、方向、周期和振幅）如何随着TA整个足迹的位置而变化。该方法将来自TA的大量数据减少为可用于进一步研究的定量记录。这项研究包括与Lars Hoffmann博士（Juelich超级计算中心）的合作，将使用卫星辐射数据检测到的重力波与使用加州大学圣地亚哥分校的技术检测到的重力波应用于TA压力数据进行比较。卫星和地面压力传感器为大气重力波的研究提供了完全不同的平台。虽然这些数据集和应用于它们的分析方法完全不同，但对结果的初步比较表明两者是一致的。这项工作有两个主要目标。首先，对大型对流事件的TA记录进行了详细研究，并与相同事件的卫星记录进行了比较。目的是确定地面压力传感器探测到的重力波在时间和位置上是否与平流层重力波一致，以及在TA足迹内探测到的重力波主要是对流的还是造山带的。加州大学圣地亚哥分校的研究小组正在研究和记录探测到的重力波的其他特征；特别是它们的速度，振幅和方向。第二，正在进行重力波发生的统计研究，目的是确定重力波发生率的日、季节和区域趋势。这项工作的一个关键成果是4年研究期间的重力波统计数据。拟议的研究对大气科学和提高对重力波对次声传播影响的理解都有贡献。

Non-technical statementThe National Science Foundation has provided funds for an unprecedented observatory for study of the Earth's interior and the atmosphere. The USArray Transportable Array is a 400-station observatory that places broadband seismic and atmospheric pressure sensors on a Cartesian grid every 70 km across an area that spans 2,000,000 square km. Seismic data from these stations have provided high-resolution images of the Earth's interior beneath the continental United States, whereas the atmospheric data at these stations provide measurements of atmospheric phenomena. In a project recently funded by NSF, researchers at UCSD developed a method to detect very long wavelength pressure disturbances, and described how they traveled across the TA. Discussions with atmospheric researchers confirmed that these pressure disturbances detected on the Earth's surface coincided with gravity waves detected by satellite measurements, at 30-50 km altitude.In this research, the researchers are making further direct comparisons of satellite observations of gravity waves with pressure disturbances recorded at ground level, with the goal of determining when and where these phenomena occur. Since gravity waves play a large part in transferring energy from near the Earth's surface to the upper atmosphere, this research is contributing to the understanding of global atmospheric circulation. Technical AbstractThe upgrade of NSF's EarthScope/USArray Transportable Array (TA) to include air pressure sensors at each station has opened up new avenues for research into atmospheric phenomena and the interaction of the atmosphere and solid Earth. This network places high quality pressure sensors on a regular, dense Cartesian grid across an area of about 2,000,000 square km, a configuration that allows for quantitative analyses of a broad range of atmospheric wave phenomena. The UCSD group is using the new pressure data to study atmospheric gravity waves at the mid-latitudes spanned by the TA. The UCSD group has developed a technique to detect gravity waves with wavelengths greater than 100 km and characterize their propagation across the TA, yielding a quantitative measure of how their characteristics (speed, direction, period, and amplitude) may change with location across the full footprint of the TA. The method reduces the large volume of data from the TA into a quantitative record that can be used for further study.The research includes a collaboration with Dr Lars Hoffmann (Juelich Supercomputing Centre) to compare gravity waves detected using satellite radiance data with those detected using UCSD's technique applied to TA pressure data. Satellites and ground-based pressure sensors provide fundamentally different platforms for studies of atmospheric gravity waves. Although these datasets and the analytical methods applied to them are completely different, a preliminary comparison of the results suggests agreement between the two. There are two main objectives of this effort. First, TA recordings of large convective events are being studied in detail and compared with satellite recordings of the same events. The objective is to determine whether gravity waves detected at ground-sited pressure sensors are coincident in time and location with stratospheric gravity waves, and whether gravity waves detected within the footprint of the TA are dominantly convective or orogenic in origin. The UCSD group is studying and documenting other characteristics of the detected gravity waves; specifically their speed, amplitude and direction. Second, a statistical study of the occurrence of gravity waves is being conducted with the objective of determining the diurnal, seasonal and regional trends in the occurrence rates of gravity waves. A key deliverable of this effort is the statistics of gravity waves during the 4-year study. The proposed research is contributing both to atmospheric science and to improved understanding of the effects of gravity waves on infrasound propagation.