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

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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.