Collaborative Research: Airborne Radar Investigation of Mountain Waves and Rotors

在过去的几十年里，山波受到了相当大的研究关注，主要是因为它们在地面和高空的破坏性风和严重湍流中发挥了重要作用。然而，人们对与山波有关的最动荡的现象--大气旋涡--知之甚少：强烈的水平涡流发生在山脊背风处的波峰下。旋翼对航空构成严重威胁，对气雾剂和污染物的放样和运输很重要。用标准的大气仪器很难对转子的内部结构和动力学进行采样。旋翼的时间和空间尺度以及可变性是常规地面观测工具的一个相当大的障碍。在最近完成的地形诱导旋翼实验(T-REX)中，携带现场仪器的飞机直接穿透可能是具有挑战性的。T-REX是一项侧重于复杂地形上的大气旋翼和湍流的倡议的一部分，它是对对旋翼结构进行进一步、更深入调查的需要的回应。这项研究集中分析了怀俄明大学国王航空公司(UWKA)研究飞机上安装的怀俄明州云雷达(WCR)在两次野外战役中收集的遥感数据。除了2006年3月和4月在加利福尼亚州内华达山脉和背风欧文斯山谷上空进行的T-REX活动外，首席调查员还将使用2006年冬季进行的NASA06实地活动的数据，作为对怀俄明州东南部梅迪辛堡山脉的一系列研究飞行。研究人员将利用这些观测数据结合最先进的中尺度数值模式来研究大气旋翼的动态演变和内部结构。主要目的是描述T-REX过程中的雷达回波、运动结构以及波流和旋翼事件的演变。首席调查员将分析和合并雷达数据与现场和地面观测以及高分辨率数值模拟的模型输出，以便提供旋翼动力学的多维图像和复杂地形上边界层结构的描述。第二个目标与第一个目标密切相关，具体涉及对NASA06运动数据的分析。虽然比内华达山脉更低、更不陡峭，但梅迪辛弓和邻近山谷的轮廓，也就是NASA06战役的发源地，引发了独特的海浪流动。强大且无处不在的雷达回波提供了一个独特的机会来填补T-REX雷达数据集的空白，但也允许比较不同的流型以及将T-REX分析扩展到不同的环境条件。智力价值：这项研究的科学价值在于通过机载多多普勒雷达在高分辨率(~30米)下收集的横截面数据来调查山波和旋翼事件以及内部旋翼结构。通过盖层和旋翼云的双多普勒反演得到的流动运动学的二维表示将为理解大气旋翼的动力演化和结构增加重要的观测维度。首席调查员将首次将航空遥感数据与飞行水平的现场数据合并，以记录山区地形上波动和内部旋翼结构的物理特性和结构。智能的优点还在于协同使用先进的遥感技术和高分辨率的大气数值模拟，以实现对复杂地形中空气流动动力学的进一步了解。广泛影响：这项研究的结果有可能提高复杂地形下的航空安全。美国西部约60%的通用航空事故和事件与山波和晴空湍流有关。联邦航空局和飞行学校将受益于对旋翼和山脉背风面大范围湍流的切实解释和逼真描绘。这项研究的结果将通过讲座、研讨会和会议报告的形式与更广泛的研究社区分享。它们还将被纳入内华达州雷诺大学、怀俄明大学和克罗地亚萨格勒布大学中尺度气象学的高级本科生和研究生课程。

Mountain waves have received considerable research attention over the past several decades, primarily for the important role they play in association with damaging winds and severe turbulence both near the ground and aloft. Yet, little is known about the most turbulent of the phenomena associated with mountain waves, that of atmospheric rotors: intense horizontal vortices occurring under wave crests in the lee of mountain ridges. Rotors pose a serious threat to aviation and are important for the lofting and transport of aerosols and contaminants. The internal structure and dynamics of rotors are extremely difficult to sample with standard atmospheric instrumentation. The temporal and spatial scales as well as the variability of rotors are a considerable hurdle to conventional, ground-based, observational tools. Direct penetrations by aircraft carrying in situ instrumentation, as was done during the recently completed Terrain-induced Rotor Experiment (T-REX), can be challenging. T-REX is part of an initiative focused on atmospheric rotors and turbulence over complex terrain and it represents a response to the need for further, more in depth, investigations on the structure of rotors. This research focuses on the analysis of remote sensing data collected with the Wyoming Cloud Radar (WCR) installed on board the University of Wyoming King Air (UWKA) research aircraft during two field campaigns. In addition to the T-REX campaign, which took place over the Sierra Nevada range and the lee-side Owens Valley in California, in March and April 2006, the Principal Investigators will use data from the NASA06 field campaign, which was conducted in the winter of 2006, as a series of research flights over the Medicine Bow range in southeastern Wyoming. The researchers will use these observational data in conjunction with a state-of-the-art mesoscale numerical model to investigate the dynamical evolution and internal structure of atmospheric rotors. The main objective is to describe the radar echo, kinematic structure, and evolution of wave flow and rotor events during T-REX. The Principal Investigators will analyze and merge radar data with in situ and ground-based observations as well as model output from high-resolution numerical simulations in order to provide a multi-dimensional picture of the rotor dynamics and depictions of the boundary-layer structure over complex terrain. A second objective, closely connected to the primary one, specifically deals with the analysis of data from the NASA06 campaign. Although lower and less steep than the Sierra Nevada, the profile of the Medicine Bow and of the adjacent valleys, where the NASA06 campaign took place, induces distinct wave flows aloft. The strong and ubiquitous radar echoes provide a unique opportunity to fill in gaps within the T-REX radar dataset, but also allow for comparisons between different flow regimes as well as extension of T-REX analyses to different environmental conditions. Intellectual Merit: The scientific merit of the research resides in investigation of mountain waves and rotor events and internal rotor structure through cross-sectional data collected by airborne multi-Doppler radar at high resolution (~30m). The two-dimensional representation of the flow kinematics derived via dual- Doppler retrievals across cap and rotor clouds will add important observational dimension to the understanding of dynamical evolution and structure of atmospheric rotors. For the first time, the Principal Investigators will merge airborne remote sensing data with in situ data at flight level to document the physical properties and structures of waves and internal rotor structure over mountainous terrain. The intellectual merit also lies in the synergistic use of advanced remote sensing techniques and high-resolution atmospheric numerical modeling to achieve further improvements in understanding of airflow dynamics in complex terrain.Broader Impact: Results of this research have the potential to improve aviation safety in complex terrain. About 60% of general aviation accidents and incidents in the western United States are associated with mountain-wave and clear-air turbulence. FAA and flight schools will benefit from tangible interpretations and realistic portrayals of rotors and large scale turbulence in the lee of the mountains. The results of this research will be shared with a wider research community in the form of lectures, seminars, and conference presentations. They will also be incorporated into upper-level undergraduate and graduate courses in mesoscale meteorology at the University of Nevada Reno, the University of Wyoming, and the University of Zagreb, Croatia.