A fine calibration of the depolarization ratio is required for a detailed interpretation of lidar-observed polar stratospheric clouds. We propose a procedure for analyzing data by using atmospheric depolarization lidar. The method is based on a plot of δ T versus (1 - R T -1), where δ T is the total depolarization ratio and R T is the total backscattering ratio. Assuming that there are only spherical particles in some altitude ranges of the lidar data, the characteristics of the plot of δ T versus (1 - R T -1) lead to a simple but effective calibration method for δ T . Additionally, the depolarization of air molecules δ m can be determined in the process of δ T calibration. We compared determined values with theoretically calculated values for the depolarization of air to test the proposed method. The δ m value was calculated from the lidar data acquired at Ny-Ålesund (79 °N, 12 °E), Svalbard in winter 1994–1995. When only sulfate aerosols were present on 24 December 1994, δ m was 0.46 ± 0.35%. When the particles consisted of sulfate aerosols and spherical particles of polar stratospheric clouds on 4 January 1995, δ m was 0.45 ± 0.07%. Both δ m values were in good agreement with the theoretically calculated value, 0.50 ± 0.03%.
© 2001 Optical Society of America
Original Manuscript: September 29, 2000
Revised Manuscript: July 1, 2001
Published: December 20, 2001
Hiroshi Adachi, Takashi Shibata, Yasunobu Iwasaka, and Motowo Fujiwara, "Calibration method for the lidar-observed stratospheric depolarization ratio in the presence of liquid aerosol particles," Appl. Opt. 40, 6587-6595 (2001)