LIDAR Measurements of Optical Extinction in the Lower Troposphere.
The capability of lidar for making quantitative optical extinction measurements on the lower troposphere has been assessed through an extensive body of lidar data in conjunction with simultaneous in situ data obtained through particle concentration measurements on the atmosphere, and through comparison with atmospheric models which we have developed to represent various atmospheric conditions observed with the lidar. Using this dual approach it has been possible to evaluate the extent to which lidar can be used as a stand-alone diagnostic tool to measure the extinction coefficient, to determine general levels of uncertainty in the derived extinction profiles for a variety of atmospheric conditions likely to be encountered, and to indicate the level of refinement of current inversion techniques beyond which further improvements are unnecessary or undesirable. The intercomparisons of lidar- and in situ-derived extinction values have also demonstrated the lidar capabilities for making these measurements. Results indicate that the level of accuracy of the lidar extinction data is at least as good as that derived from the in situ data. However, lidar is capable of making these measurements with excellent spatial and temporal resolution. The results of our analyses also indicate that the optimum inversion techniques for the analysis of lidar soundings on an operational basis are the simpler ones. The accuracy of the derived profiles from these inversion methods is generally not as good as that available through the use of more sophisticated techniques, but their simplicity and reliability warrants their application.
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- Physics: Electricity and Magnetism; Physics: Optics