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

地球的中间层和低热层(MLT)包含热结构和风结构，可以支持大量的导管波，这些波局限于条件支持其存在和传播的局部地区。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，它们可能会增长到很大的幅度，水平传播很长距离，并在远离其来源的地方引起变化。同时在两个管道中传播的波在更远的距离上可能比限制在单一管道中的波携带更大的能量。越来越多的证据表明，大振幅导管波与MLT的广泛变化频繁发生有关。与非导管波相比，导管波可能会影响更广泛的大气区域，因为前者可能在消散之前水平地长距离传递能量。即使是微弱的或部分的导流也可能导致波能的显著重新分配。导管波为低纬对流区等多波源提供了一种机制。需要更好地理解和描述波可能获得较大振幅、从远距离源转移能量以及在MLT中产生波的效应的过程，以帮助我们更好地理解MLT的波浪控制。这一特征将为改进大气环流模式的波浪阻力参数化方案奠定基础。这项研究是以数据分析为基础的理论研究，旨在解决有关导管波在MLT中作用的悬而未决的问题。具体目标是评估实际MLT条件下管道中的波能积聚以及管道中能量的传播和泄漏。这项研究将使用理论、数值模拟，并与从大量的导管准单色波事件数据库中观测的导管波进行比较。数据将从不同地点(安第斯激光雷达观测站、毛伊岛、阿德莱德和爱丽丝斯普林斯)的气辉成像仪、激光雷达和雷达以及定时卫星上的SABER仪器获得。这项研究的重点是在中间层和低热层管道系统中影响全球波能重新分配的一个基本上未被探索的机制。这项工作将确定，在低层大气中由多产波源填充的管道在远离震源区的地方具有相当大的地球物理重要性。这一结果将导致发展模拟能力，以研究作为一种波浪增长手段的导管以及大气区域之间垂直和水平方向的波能重新分配。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继续研究的机会。

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.