Airborne forward pointing UV Rayleigh lidar for remote clear air turbulence (CAT) detection: system design and performance

摘要

A high-performance airborne UV Rayleigh lidar system was developed within theEuropean project DELICAT. With its forward-pointing architecture it aims atdemonstrating a novel detection scheme for clear air turbulence (CAT) for anaeronautics safety application. Due to its occurrence in clear and clean air athigh altitudes (aviation cruise flight level), this type of turbulence evadesmicrowave radar techniques and in most cases coherent Doppler lidar techniques.The present lidar detection technique relies on air density fluctuationsmeasurement and is thus independent of backscatter from hydrometeors andaerosol particles. The subtle air density fluctuations caused by the turbulentair flow demand exceptionally high stability of the setup and in particular ofthe detection system. This paper describes an airborne test system for thepurpose of demonstrating this technology and turbulence detection method: ahigh-power UV Rayleigh lidar system is installed on a research aircraft in aforward-looking configuration for use in cruise flight altitudes. Flight testmeasurements demonstrate this unique lidar system being able to resolve airdensity fluctuations occurring in light-to-moderate CAT at 5 km or moderate CATat 10 km distance. A scaling of the determined stability and noisecharacteristics shows that such performance is adequate for an application incommercial air transport.