Wave Characteristics from the COSMIC and CHAMP Global Positioning System (GPS) Temperature Profiles

重力波在地球大气层中无处不在。 它们在动量和化学成分的垂直传输中发挥重要作用，现在所有的全球气候模型都包括重力波效应的参数化。 然而，这些参数化的观测约束不足，因为重力波的时间和空间尺度太短，无法通过传统的气象观测网络来解决。主要调查员将利用从全球定位系统信号无线电掩星获得的新获得的高垂直分辨率温度分布图，得出关于重力波活动和动量输送的全球信息。 这些数据是由低地球轨道上的两个卫星星座CHAMP获得的（发射小型卫星有效载荷）和COSMIC（气象、电离层和气候星座观测系统），每天提供数千份温度分布图，几乎均匀地分布在地球仪上。利用这些全球数据，PI将通过消除投射到大的水平空间尺度上的那些变化来提取重力波对温度结构的贡献。 重力波的水平波数和传播方向将由相邻温度分布之间的相位差确定，由于波浪活动引起的水平动量的垂直通量将被估计-这是必须通过全球模型中的重力波参数化计算的量。GPS数据的数量和全球覆盖范围将允许PI将重力-波浪活动与不同的来源，其中包括地形，对流，风切变，天气锋，和地转调整。 将使用射线追踪方法探索观测到的波与可能的源之间的联系。全球数据还将使人们能够以前所未有的准确度确定大规模大气波（例如赤道开尔文波）的结构和变异性。 随着数据的积累，将有可能探索重力波活动的时间变化及其与行星尺度大气环流变化的关系，例如准两年振荡和平流层突然变暖。这项研究的更广泛影响是更好的引力波信息对引力开发者的重要性-全球气候模式的波浪参数化和研究波浪与高纬度卷云的相互作用。

Gravity waves are ubiquitous in Earth's atmosphere. They play important roles in the vertical transport of momentum and chemical constituents, and all global climate models now include a parameterization of gravity-wave effects. These parameterizations are, however, poorly constrained by observations, since gravity waves have time and space scales too short to be resolved by the conventional meteorological observing network. The principal investigators (PIs) will derive global information about gravity wave activity and momentum transport using newly available, high vertical resolution, temperature profiles obtained from the radio occultation of global positioning system (GPS) signals. These data are acquired by two constellations of satellites in low Earth orbit, CHAMP (Challenging Minisatellite Payload) and COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate), which provide thousands of temperature profiles each day, distributed nearly uniformly over the globe.Using these global data, the PIs will extract the gravity-wave contribution to the temperature structure by removing those variations that project onto large horizontal spatial scales. The horizontal wavenumbers and propagation directions of gravity waves will be determined from the phase differences between adjacent temperature profiles, and the vertical flux of horizontal momentum due to the wave activity will be estimated - this is the quantity that must be calculated by gravity-wave parameterizations in global models.The quantity and global coverage of the GPS data will allow the PIs to associate gravity-wave activity with different sources, which include topography, convection, wind shear, synoptic fronts, and geostrophic adjustment. The connections of observed waves to likely sources will be explored using ray-tracing methods. The global data will also permit the structures and variability of large-scale atmospheric waves, such as equatorial Kelvin waves, to be determined with unprecedented accuracy. As data accumulate over time, it will be possible to explore the temporal variability of gravity-wave activity and its associations with variations in the planetary scale circulation of the atmosphere, such as the quasi-biennial oscillation and sudden stratospheric warmings.Broader impacts of this research are in the importance of better gravity-wave information to the developers of gravity-wave parameterizations for global climate models and for research on wave interactions with high-latitude cirrus clouds.