Optical properties of Asian dusts in the free atmosphere measured by Raman lidar at Taipei,Taiwan |
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| Affiliation: | 1. Department of Earth and Environmental Sciences, Korea University, Seoul, South Korea;2. Department of Environmental Science, Hankuk University of Foreign Studies, Yongin, South Korea;3. Air Quality Division, National Institute of Environmental Research, Inchon, South Korea;1. Andalusian Institute for Earth System Research (IISTA-CEAMA), University of Granada, Autonomous Government of Andalusia, 18006 Granada, Spain;2. Department of Applied Physics, University of Granada, Granada, Spain;3. Facultad de Ciencias, Departamento de Física, Universidad Nacional de Colombia, Medellín, Colombia;4. Federal Office of Meteorology and Climatology MeteoSwiss, Payerne, Switzerland;5. Atmospheric Optics Group (GOA-UVa), Valladolid University, Valladolid, Spain;6. Institute of Research and Nuclear Energy, IPEN, São Paulo, Brazil;7. Physical Sciences Department, School of Science, EAFIT University, Medellín, Colombia;8. Facultad de Minas, Departamento de Geociencias y Medio Ambiente, Universidad Nacional de Colombia, Medellín, Colombia;1. Institute of Earth, Astronomy, and Atmosphere, Brain Korea 21 Program, Department of Atmospheric Sciences, Yonsei University, Seoul, Republic of Korea;2. Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA;3. NASA Goddard Space Flight Center, Greenbelt, MD, USA;4. Research Institute of Basic Sciences, Chungnam National University, Daejeon, Republic of Korea;5. Atmospheric Chemistry Department, Max-Planck Institute of Chemistry, P.O. Box 3060, 55020 Mainz, Germany;6. Department of Atmospheric and Oceanic Sciences, University of Maryland, College Park, MD, USA |
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| Abstract: | The optical properties (extinction-to-backscatter ratio, backscattering, depolarization, and backscatter-related Angstrom exponent) and height distribution of Asian dusts were measured using a two-wavelength Raman/depolarization lidar at Taipei, Taiwan, during the Asian dust seasons in 2004 and 2005. Dust layers were frequently observed in the free atmosphere (1–6 km). Dust optical thickness ranged from 0.01 to 0.55; backscatter-related Angstrom exponents ranged from 0.42 to 1.47; and lidar ratios (extinction-to-backscatter ratio) for 355 nm ranged from 32 to 72 sr (steradian). The mean values of dust particle depolarization and extinction coefficient are and , respectively, which are close to the moderate dust depolarizations and extinctions observed in free atmosphere in China and Japan. Backscatter-related Angstrom exponents were found correlated positively with lidar ratio and negatively with particle depolarization, indicating that the dust optical characteristics are predominated by size distribution. Dusts were found to tend to exhibit unusual low depolarization properties under moist conditions (relative humidity ), and the possible explanations are discussed. |
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