Collaborative Research: CEDAR: High-Resolution Imaging of Instability Dynamics and Breakdown

这是美国航空航天公司和GATS公司之间为期3年的合作研究，目的是在智利安第斯激光雷达天文台（ALO）安装一台新的气辉相机，并利用这些数据研究中层顶附近的湍流过程。在80 ~ 100 km高空区域的数值模式中，湍流粘度是一个关键的未知参数。众所周知，这是非常难以衡量的。该项目将提供一种测量该参数的方法，在这个重要的大气区域，湍流粘度可能变化3个数量级。本研究的结果也将有助于对伴随流动不稳定的流体动力学有更广泛的了解。具体来说，这个项目将利用航空航天公司？美国的新型高分辨率红外相机（AIC2）采用快速光学和2048 x 2048红外探测器，以2秒的图像节奏对30米像素大小的OH气辉进行成像。ALO站点还包括Na风温度激光雷达和流星雷达。来自AIC2和其他ALO仪器的数据将用于研究开尔文-亥姆霍兹不稳定性（KHIs）分解为湍流并测量湍流粘度。这项新技术将允许在各种背景条件下以及在每日和季节性时间尺度上表征湍流粘度。测量结果将与高分辨率直接数值模拟相结合，以产生迄今为止最完整的KHI分解及其演变为湍流的图像。

This is a 3-year collaborative investigation between The Aerospace Corporation and GATS Inc. to place a new airglow camera at the Andes Lidar Observatory (ALO) in Chile and use those data to study turbulent processes near the mesopause. Turbulent viscosity is a critical unknown parameter in numerical models of the 80 to 100 km altitude region. It is notoriously very difficult to measure. This project will provide a method of measuring this parameter in this important atmospheric region where turbulent viscosity may vary by 3 orders of magnitude. The results of this study will also contribute to a more general understanding of fluid dynamics accompanying flow instabilities. Specifically, this project will utilize the Aerospace Corporation?s new high-resolution infrared camera (AIC2) that uses fast optics and a 2048 x 2048 IR detector to image the OH airglow at 30 m pixel size with a 2 s image cadence. The ALO site also includes a Na wind-temperature lidar and a meteor radar. Data from the AIC2 and the other ALO instruments will be used to investigate the breakdown into turbulence of Kelvin-Helmholtz instabilities (KHIs) and to measure the turbulent viscosity. This new technique will allow characterization of the turbulent viscosity for a variety of background conditions and over daily and seasonal timescales. The measurements will be combined with high-resolution direct numerical simulations to produce the most complete picture to date of KHI breakdown and its evolution into turbulence.