Field-deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor

摘要

A field-deployable water vapor profiling instrument that builds on thefoundation of the preceding generations of diode-laser-based differentialabsorption lidar (DIAL) laboratory prototypes was constructed andtested. Significant advances are discussed, including a unique sharedtelescope design that allows expansion of the outgoing beam for eye-safeoperation with optomechanical and thermal stability; multistage opticalfiltering enabling measurement during daytime bright-cloud conditions; rapidspectral switching between the online and offline wavelengths enablingmeasurements during changing atmospheric conditions; and enhanced performanceat lower ranges by the introduction of a new filter design and the additionof a wide field-of-view channel. Performance modeling, testing, andintercomparisons are performed and discussed. In general, theinstrument has a 150 m range resolution with a 10 min temporal resolution;1 min temporal resolution in the lowest 2 km of the atmosphere isdemonstrated. The instrument is shown capable of autonomous long-term fieldoperation – 50 days with a > 95% uptime – under a broad set ofatmospheric conditions and potentially forms the basis for a ground-basednetwork of eye-safe autonomous instruments needed for the atmosphericsciences research and forecasting communities.