Classification of Polar Stratospheric Clouds Using LIDAR Measurements From the SAGE III Ozone Loss and Validation Experiment

Report No. ARL-TR-4154
Authors: Melvin A. Felton, Jr., Thomas A. Kovacs,
Date/Pages: June 2007; 36 pages
Abstract: Backscatter LIDAR measurements from the stratospheric aerosol and gas experiment (SAGE) III ozone loss and validation experiment (SOLVE) have been used to identify classes of polar stratospheric clouds (PSCs) and their corresponding characteristics. Volume backscatter at 532 nm (¿532) and 1064 nm (¿1064), scattering ratio at 532 nm (R532) and 1064 nm (R1064), aerosol depolarization (¿a), and color ratio (¿532/¿1064), and temperature (T) were used to categorize PSCs via principal component analysis (PCA) and Cluster Analysis (CA). The clusters found in this study are consistent with previous studies of PSCs of types Ia (R532 < 1.5 and ¿a > 0.1), Ia-enhanced (R532 > 1.4 and ¿a > 0.1), Ib (R532 > 2 and ¿a < 0.025), and II (R532 > 7 and ¿a > 0.1). In addition, a cluster predominantly found on the outside edges of clouds, which does not fit the definition of these PSCs, which has low R532 and ¿a values, was found. The clustering analysis of PSC data provides an objective and automated method for the production of image plots that show a two-dimensional distribution of the PSC particle types. Such capabilities will be useful for analyzing large data sets such as will be produced by space-borne LIDARS (laser identification and ranging system).
Distribution: Approved for public release
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Last Update / Reviewed: June 1, 2007