Collaborative Research: Airborne Radar Investigation of Mountain Waves and Rotors

在过去的几十年里，山波受到了相当多的研究关注，主要是因为它们在近地面和高空的破坏性风和严重湍流中所起的重要作用。然而，人们对与山波有关的最动荡的现象，即大气旋涡所知甚少：在山脊背风处的波峰下发生强烈的水平涡旋。旋翼对航空构成严重威胁，对气溶胶和污染物的悬浮和运输至关重要。转子的内部结构和动力学是非常困难的采样与标准的大气仪器。时间和空间尺度以及旋翼的可变性是传统的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，携带原位仪器的飞机进行直接穿透是具有挑战性的。T-REX是一项专注于复杂地形上的大气旋翼和湍流的计划的一部分，它代表了对旋翼结构进一步、更深入研究的需求的回应。本研究的重点是分析怀俄明州云雷达（WCR）在两次野外战役中收集的遥感数据，该雷达安装在怀俄明大学空中国王（UWKA）研究飞机上。除了2006年3月和4月在内华达山脉和加利福尼亚背风的欧文斯山谷进行的T-REX活动之外，主要调查人员还将使用2006年冬季在怀俄明州东南部的梅迪辛堡山脉进行的一系列研究飞行的NASA06实地活动的数据。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型来研究大气旋翼的动力学演变和内部结构。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。主要研究人员将分析和合并雷达数据、现场和地面观测数据以及高分辨率数值模拟的模型输出，以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NASA06活动的数据分析。虽然比内华达山脉更低，也不那么陡峭，但梅迪辛弓和NASA06活动发生地附近山谷的轮廓，在高空诱导出明显的波流。强大且无处不在的雷达回波为填补T-REX雷达数据集的空白提供了独特的机会，同时也允许对不同流态进行比较，并将T-REX分析扩展到不同的环境条件。智力优势：本研究的科学价值在于利用机载多普勒雷达采集的高分辨率（~30m）横截面数据对山波、旋翼事件和旋翼内部结构进行研究。通过顶云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了解大气旋翼的动力演变和结构增加重要的观测维度。首席研究人员将首次将机载遥感数据与飞行水平的原位数据合并，以记录山区地形上波浪和内部旋翼结构的物理特性和结构。智力上的优点还在于先进的遥感技术和高分辨率大气数值模拟的协同使用，以进一步提高对复杂地形下气流动力学的理解。更广泛的影响：本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。美国联邦航空局和飞行学校将受益于有形的解释和现实的旋翼和大规模湍流在山区背风处的描绘。这项研究的结果将以讲座、研讨会和会议报告的形式与更广泛的研究团体分享。它们还将被纳入内华达大学里诺分校、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.