Collaborative Research: Finite Amplitude Gravity Wave Trains in the Upper Mesosphere - Lower Thermosphere Duct System: Build Up and Leakage of Energy from Local and Distant Sources

地球的中间层和低层热层（MLT）包含热和风结构，可以支持大量的导管波，这些导管波被限制在局部区域，那里的条件支持它们的存在和传播。通常，波可以同时在多个管道中传播。这些波的独特之处在于，它们可以增长到很大的振幅，水平传播很远的距离，并在远离它们的源头的地方引起变化。同时通过两个管道的波比局限于单个管道的波在更远的距离上携带更大的能量。越来越多的证据表明，大振幅的导管波与MLT广泛变化的频繁发生有关。与非导管波相比，导管波可以影响更广泛的大气区域，因为导管波在消散之前可以在较长的距离上水平转移能量。即使是微弱的或部分的导管也会引起波能的重新分配。导管波为诸如低纬度对流带的多产波源提供了一种机制。波可能获得大振幅的过程，从遥远的来源传递能量，并在波未被捕获的MLT中产生影响，需要更好地理解和更好地表征，以帮助提高我们对MLT波控制的理解。这种表征将是改进一般环流模式的波阻参数化方案的基础。本研究是一项以数据分析为基础的理论研究，旨在解决有关导管波在MLT中的作用的悬而未决的问题。具体的目的是评估在实际的MLT条件下，波能在MLT管道内的积累和能量从管道的传播和泄漏。该研究将使用理论、数值模拟和从导管准单色波事件的广泛数据库中对导管波的观测结果进行比较。数据将从不同地点的气辉成像仪、激光雷达和雷达（安第斯激光雷达天文台、毛伊岛、阿德莱德和爱丽丝泉）以及TIMED卫星上的SABER仪器获得。研究的重点是影响中间层和低层热层管道系统中波能全球再分配的一个很大程度上尚未探索的机制。这项工作将证明，在远离震源区域的较低层大气中，由丰富的波源组成的管道具有相当重要的地球物理意义。这些结果将导致模拟能力的发展，用于研究作为波增长手段的管道和大气区域之间垂直和水平的波能量再分配。它将支持在现有地点进行协调的多仪器调查，并为一名女科学家和一名研究生提供持续的研究机会。

Earth's mesosphere and lower thermosphere (MLT) contain thermal and wind structures that can support a large population of ducted waves that are confined to localized regions where conditions support their existence and propagation. Often, waves can travel simultaneously in multiple ducts. Distinctive aspects of these waves are that they may grow to large amplitudes, travel large distances horizontally and induce changes far from their sources. Waves ducted in two ducts simultaneously may carry much greater energy over larger distances than waves confined to a single duct. There is a growing body of evidence that large-amplitude ducted waves are associated with frequent occurrences of extensive changes in the MLT. Ducted waves may affect broader regions of the atmosphere than non-ducted waves since the former may transfer energy horizontally over long distances prior to dissipation. Even weak or partial ducting may cause a significant redistribution of wave energy. Ducted waves provide a mechanism for prolific wave sources such as in low-latitude convective zones. The processes by which waves may attain large amplitudes, transfer energy from distant sources and produce effects in the MLT where the waves become untrapped need to be better understood and better characterized to help improve our understanding of the wave control of the MLT. Such a characterization would be the basis for improved parameterization schemes of wave drag for general circulation models. This investigation is a theoretical study supported by data analysis to address outstanding questions concerning the role of ducted waves in the MLT. The specific objectives are to assess the buildup of wave energy in MLT ducts and the propagation and leakage of energy from ducts under realistic MLT conditions. The study will use theory, numerical modeling, and comparisons to observations of ducted waves from an extensive data base of ducted quasi-monochromatic wave events. Data will be obtained from airglow imagers, lidar and radar from diverse locations (Andes Lidar Observatory, Maui, Adelaide, and Alice Springs) and from the SABER instrument on the TIMED satellite. The research focuses on a largely unexplored mechanism for effecting the global redistribution of wave energy in the mesospheric and lower-thermospheric ducting system. The work will establish that ducts populated by prolific wave sources in the lower atmosphere are of considerable geophysical importance far from the source regions. The results will lead to the development of modeling capabilities for investigating ducting as a means of wave growth and the redistribution of wave energy between regions of the atmosphere, both vertically and horizontally. It will support coordinated multi-instrument investigations at existing sites, and provide a continuing research opportunity for a female scientist and a graduate student.