25 September 2007 Intercomparison of calibration techniques for 1064nm NIR elastic lidar
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In conventional lidar, calibration of the backscatter signal is performed by comparing the returns to aerosol clean layers where the backscatter signal can be calculated directly. Unfortunately, in the IR, this approach is not practical since the aerosol contribution to the signal is always a significant fraction even for high altitudes. Two approaches which have been suggested include the calibration from high altitude cirrus clouds and the calibration from low altitude stratocumulous (water phase) clouds. In this paper, we perform an inter-comparison of these methods over long time periods both as a means to assess the accuracy of the calibration methods as well as determining the stability of the lidar calibration coefficient. To improve upon the standard calibration using the cirrus cloud approach, a forward iterative integration scheme is employed from below cloud base to determine the backscatter at 532nm. It is found that the cirrus cloud approach in reasonable agreement with the low altitude water cloud method. Furthermore, a small 15% discrepancy between the methods is explained based on reasonable multiple scattering corrections which must be introduced into the low altitude water cloud technique.
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Shuki Chaw, Shuki Chaw, Yonghua Wu, Yonghua Wu, Barry Gross, Barry Gross, Fred Moshary, Fred Moshary, Samir Ahmed, Samir Ahmed, } "Intercomparison of calibration techniques for 1064nm NIR elastic lidar", Proc. SPIE 6760, Infrared, Mid-IR, and Terahertz Technologies for Health and the Environment II, 676007 (25 September 2007); doi: 10.1117/12.734585; https://doi.org/10.1117/12.734585

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