Transparency of the atmosphere to short horizontal wavelength gravity waves
Transparency of the atmosphere to short horizontal wavelength gravity waves
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DOI：
10.1029/2007jd009682
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发表时间：
2008-12
影响因子：
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通讯作者：
P. Preusse;S. Eckermann;M. Ern
中科院分区：
文献类型：
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作者：
P. Preusse;S. Eckermann;M. Ern
[1]我们使用的理论和全球射线模型来研究如何重力波的潜在全球运输动量通量从低层大气到中层和低热层（MLT）的水平波长和地面相速度的变化。射线建模是使用重力波区域或全球射线追踪器（GROGRAT）进行的，该追踪器与0至100公里高度的真实三维全球风和温度相连接，通过将较低高度的分析场与更高高度的GCM结果相融合来指定。我们专注于重力波在短的10至50公里的水平波长范围内，是未解决的全球模型，根据理论，可以传输可观的动量通量到MLT。不同季节的射线结果再现了一些来自简单的波理论的限制：水平波长短于10公里往往被删除的垂直反射或倏逝在源和较慢的相速度更容易临界水平去除，导致更长的水平波长和更快的地面相速度到达MLT的波的偏好。将这些发现与卫星临边和最低点探测器目前分辨的波长尺度进行比较，突出显示目前测量的波长范围和目前未分辨的波长范围。一个路线图，目前和未来的卫星测量可以结合起来，以测量全时空谱的重力波相关的涡流通量沉积和动量强迫的全球MLT。特别是，提供了新的卫星测量战略，填补目前的测量差距的建议。
[1] We use theory and global ray modeling to investigate how the potential of gravity waves to transport momentum flux globally from the lower atmosphere into the mesosphere and lower thermosphere (MLT) varies with horizontal wavelength and ground-based phase speed. Ray modeling is performed using the Gravity Wave Regional or Global Ray Tracer (GROGRAT) interfaced to realistic three-dimensional global winds and temperatures from 0 to 100 km altitude, specified by fusing analysis fields at lower altitudes to GCM results higher up. We focus on gravity waves in the short 10- to 50-km horizontal wavelength range that are unresolved by global models and, according to theory, can transport appreciable momentum flux into the MLT. Ray results for different seasons reproduce some of the limits derived from simple wave theory: that horizontal wavelengths shorter than 10 km tend to be removed by vertical reflection or evanescence at the source and slower phase speeds are more prone to critical level removal, leading to a preference for waves with longer horizontal wavelengths and faster ground-based phase speeds to reach the MLT. These findings are compared to the wavelength scales currently resolved by satellite limb and nadir sounders, highlighting wavelength ranges currently measured and those currently unresolved. A road map is developed for how current and future satellite measurements can be combined to measure the full space-time spectrum of gravity waves relevant to eddy flux deposition and momentum forcing of the global MLT. In particular, recommendations for new satellite measurement strategies that fill current measurement gaps are provided.