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Depolarization property of cirrus clouds over Hanoi

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The clouds are found mainly to consist of floating ice crystals, which can reflect strongly incoming radiation. Lidar measurements provide an opportunity to study the microphysics and ice compositions of cirrus clouds. We have developed a polarization lidar system to measure the depolarization characteristics of the lower atmosphere over Hanoi. | Communications in Physics, Vol. 27, No. 4 (2017), pp. 339-344 DOI:10.15625/0868-3166/27/4/10836 DEPOLARIZATION PROPERTY OF CIRRUS CLOUDS OVER HANOI TIEN PHAM MINHa,b , TUAN NGUYEN XUANc , TRUNG DINH VANc , MANH LE DUYd , AND HAI BUI VANe a Ho Chi Minh City Institute of Physics, Vietnam Academy of Science and Technology, No 1 Mac Dinh Chi, Ben Nghe, District 1, Ho Chi Minh City, Vietnam b Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18, Hoang Quoc Viet, Cau Giay, Ha Noi, Vietnam c Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi, Vietnam d Institute of Research and Development, Duy Tan University, No. 3 Quang Trung, Da Nang, Vietnam e Le Quy Don Technical University, 236 Hoang Quoc Viet, North Tu Liem, Hanoi, Vietnam † E-mail: bvhaihsh@yahoo.com, bvhaihsh@mta.edu.vn Received 10 October 2017 Accepted for publication 27 October 2017 Published 22 December 2017 Abstract. Cirrus cloud is one of the most commonly occurring cloud types globally. The clouds are found mainly to consist of floating ice crystals, which can reflect strongly incoming radiation. Lidar measurements provide an opportunity to study the microphysics and ice compositions of cirrus clouds. We have developed a polarization lidar system to measure the depolarization characteristics of the lower atmosphere over Hanoi. From our measurements of cirrus clouds over the period from 2010 to 2012, the depolarization ratio of cirrus clouds is found to be very high ranging from 20% up to 80%, indicating large fraction of backscattering from ice crystals. We find a trend of increasing depolarization ratio with height and decreasing temperature. We also compare our lidar measurements with other results obtained by lidar technique in other regions of the world. Keywords: lidar, atmosphere, depolarization. Classification numbers: 42.68.Ay, 92.60.Ta. c 2017 Vietnam Academy of Science and Technology 340 DEPOLARIZATION .