Developing a portable, autonomous aerosol backscatter lidar for network or remote operations

[摘要] Lidar has the ability to detect the complex vertical structure of theatmosphere and can therefore identify the existence and extent of aerosolswith high spatial and temporal resolution, making it well suited forunderstanding atmospheric dynamics and transport processes. EnvironmentCanada has developed a portable, autonomous lidar system that can bemonitored remotely and operated continuously except during precipitationevents. The lidar, housed in a small trailer, simultaneously emits twowavelengths of laser light (1064 nm and 532 nm) at energies ofapproximately 150 mJ/pulse/wavelength and detects the backscatter signal at1064 nm and both polarizations at 532 nm. For laser energies of thismagnitude, the challenge resides in designing a system that meets theairspace safety requirements for autonomous operations. Through thecombination of radar technology, beam divergence, laser cavity interlocks andusing computer log files, this risk was mitigated. A Continuum Inlite smallfootprint laser is the backbone of the system because of three designcriteria: requiring infrequent flash lamp changes compared to previousNd : YAG Q-switch lasers, complete software control capability and abuilt-in laser energy monitoring system. A computer-controlled interface wasdesigned to monitor the health of the system, adjust operational parametersand maintain a climate-controlled environment. Through an Internetconnection, it also transmitted the vital performance indicators and datastream to allow the lidar profile data for multiple instruments from nearground to 15 km, every 10 s, to be viewed, in near real-time via a website.The details of the system design and calibration will be discussed and thesuccess of the instrument as tested within the framework of a national lidarnetwork dubbed CORALNet (Canadian Operational Research Aerosol LidarNetwork). In addition, the transport of a forest fire plume across thecountry will be shown as evidenced by the lidar network, HYSPLIT backtrajectories, MODIS imagery and CALIPSO overpasses.

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