A field test has been carried out to compare calculations made from lidar data to direct sensor measurements as tools for determining extinction as a function of altitude in the first kilometer of the earth’s atmosphere during the presence of haze layers and stratus clouds; 1.06-μm wavelength lidar returns were reduced using methods based on the stable solution to the lidar equation proposed by Klett. Direct sensor data were obtained from particulate spectrometers and a point visibility meter carried aloft by a tethered hydrogen balloon. The extinction profiles obtained from reduced lidar data are qualitatively in excellent agreement with those from the airborne payload. At moderate to high extinction values encountered in stratus clouds quantitative agreement is reasonably good; in haze conditions the agreement is less satisfactory, not only between the lidar results and those from the direct sensors, but between the results from the particle size distribution data and visibility meter data as well. Nevertheless, considering that extinction can vary over 4 orders of magnitude in such profiles, it is concluded that lidar is a quantitatively useful tool for studying stratus layers and is a particularly good means for determining ceiling altitude.
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