Network Observation of Asian Dust by Dual-polarization Lidars During ACE-Asia IOP

Mie scattering lidars with capability of depolarization measurement were intensively operated in the spring 2001 to detect the vertical structure and transport of the Asian dust in China and Japan. Lidars at Beijing (116.3E, 39.9N), Nagasaki (129.9E, 32.8N), and Tsukuba (140.1E, 36.1N) were operated continuously, regardless of whether, for statistical study of dust events. Each lidar obtained profiles every 15 minutes and data of rainy/cloudy hours were excluded later. Scattering particles of clear hours were classified into spherical aerosols or mineral dusts at each altitude by their depolarization ratio, and the aerosol extinction coefficient was calculated by Fernald's method. At Beijing Asian dust was often detected near the surface. Many dust events continued for several days, and some of them seemed to reach Nagasaki with delay of a few days. Although few surface dust events were identified at Tsukuba, several events in the free troposphere (above 3 km) were detected. Vertical structure of such dusts observed at Tsukuba and Nagasaki was sometimes resembling each other. Non-dust aerosols were detected continuously below 1 km at all observatory. Lidars in Tokyo (139.8E, 35.6N) and Fukuyama (133.2E, 34.5N) were also operated frequently, especially during dust events over Japan. Simultaneous profiles at Tokyo and Tsukuba (separated for 60 km) were very similar above the boundary layer. However, lower part showed some differences due to local influences. Results in Fukuyama resembled that in Nagasaki, with higher depolarization ratio than in Tokyo and Tsukuba. Also, three stations at coastal region (Tokyo, Fukuyama, and Nagasaki) were often covered by a dense, shallow aerosol layer near the surface. Observation results of the lidar network in east Asian region, including lidars not mentioned in this paper, are shown at ``Asian Lidar Observation Network Data Exchange Page'' for quick comparison.