Coherent Doppler Lidar Deployment and Data Analysis for Terrain-induced Rotor EXperiment (T-REX)

遥感仪器和数值模拟的进步现在允许更全面地探测和分析与大气转子有关的三维流体动力学细节。首席研究员（PI）将于2006年3月和4月在加利福尼亚州欧文斯谷参加一项实地实验（地形诱导旋翼实验；T-REX），旨在调查大气旋翼。亚利桑那州立大学将部署其相干多普勒激光雷达，这是一个地面能量预算站，并对收集到的数据进行实验后分析。在分析中，PI将侧重于旋涡结构及其动力学。PI将利用几种形式的信息从激光雷达数据中提取，包括双多普勒分析和四维变分数据同化。该研究的智力价值是由于以下激励的科学问题：(1)大型转子的物理尺寸，强度和下游稳定性的范围是什么？(2)波浪边界上的流动模拟表明，切变层在山丘的背风处分离，并可能卷起进入强涡度区，向下游平流。是否有证据表明这种（未被捕获的）涡旋喷射到下游大气中？它们可能在什么条件下存在？它们的量级是否大到足以对飞机构成威胁？(3)在模拟山地诱导大气旋翼时发现了副旋翼。如果它们存在，它们能有多强，又在哪里？这些漩涡是如何演变的，它们的命运又是怎样的？横向速度波动在副旋翼（旋涡伸展）的发展中有多重要？(4)在实验室流动中对波浪表面流动的模拟也显示出长而顺流的涡流，这似乎与戈特勒不稳定性有关。通常，颗粒抬升发生在流向的“线”上，这与旋涡沿下游方向排列的可能性一致。有证据表明这样的涡旋存在吗？它们在气溶胶进入旋翼区域的过程中有多重要？(5)表面通量的变化是否显著影响转子的尺寸和强度？该项目的广泛影响是由于它对提高航空安全以及了解与旋翼相关的气溶胶沉降具有重要意义。相干多普勒激光雷达数据的获取也将有利于其他T-REX研究人员。在教育方面，亚利桑那州立大学的激光雷达已被证明是本科生和研究生的优秀教学工具。由于这种类型的激光雷达已经经历了广泛的工程开发，因此在操作程序方面相对容易获得。其次，在之前的实验中，它的动态和可视化的实时输出引起了很多学生的热情。

Advances in remote sensing instruments and numerical simulations now allow more comprehensive probing and analysis of three-dimensional fluid dynamical details associated with atmospheric rotors. The Principal Investigator (PI) will participate in a field experiment (Terrain induced Rotor Experiment; T-REX) designed to investigate atmospheric rotors in Owens Valley, California, during March and April of 2006. Arizona State University will deploy its coherent Doppler lidar, a ground-based surface energy budget station, and perform post-experiment analysis of collected data. For the analysis, the PI will focus on vortical structures and their dynamics. The PI will utilize several forms of extraction of information from the lidar data, including dual-Doppler analyses, and four dimensional variational data assimilation. The intellectual merit of the research is due to the following motivating scientific questions: (1) What are the ranges of physical size, strength, and downstream stabilities of large rotors? (2) Simulations of flows over wavy boundaries indicate that shear layers become detached over the lee of the hills and may roll-up into strong regions of vorticity that advect downstream. Is there evidence for such ejection of (non-trapped) vortices into the downstream atmosphere? Under what conditions are they likely to exist, and are their magnitudes large enough to pose a hazard to aircraft? (3) Sub-rotors have been found in simulations of mountain-induced atmospheric rotors. If they exist, how strong can they be, and where are they located? How do such vortices evolve and what is their fate? How important are lateral velocity fluctuations in the development of sub-rotors (vortex stretching)? (4) Simulations of flows over wavy surfaces in laboratory flows also show evidence of long, streamwise vortices, which appear to be related to Goertler instability. Frequently, particulate lifting occurs in streamwise "lines" - consistent with the possibility of vortices aligned with the downstream direction. Is there evidence that such vortices exist and how important are they in the lofting of aerosols into the rotor domain? (5) Do variations in surface fluxes significantly affect the size and strength of rotors? The project's broader impacts are due to its significance for improving aviation safety and understanding aerosol lofting associated with rotors. The acquisition of coherent Doppler lidar data also will be beneficial to other T-REX investigators. Educationally, the Arizona State University lidar has proven to be an excellent teaching tool for undergraduate and graduate students. Because this type of lidar has gone through extensive engineering development, it is relatively accessible, in terms of operational procedures. Secondly, in prior experiments, its dynamic and visual real-time output has generated much student enthusiasm.