Measurement of Asian dust in the troposphere have been performed with Mie scattering lidars that are Multi-wavelength aerosol lidar (MWA lidar) and Automatic Continuous operated lidar (ACA lidar) at Suwon, Korea (37.2N-127.6E) in the spring of 2000-2004. These lidar systems are based on pulsed Nd:YAG and multi-receiving channels. It consists in two or three mode that MWA lidar are 355 and 532 nm backscatters and 532nm depolarization ratio, and ACA lidar are 532 and 1064 nm backscatters, 532 nm depolarization ratio, and 1064/532 nm aerosol color ratio. During five years (2000-2004) of intensive observation of Asian dust more than 56 episodes and 2,177 vertical profiles were successfully measured. The significant dust in March 2002 to May 2003 showed the dust layers are located in the altitude range of 0.2-3 km. In this case, the depolarization ratio is large than 15% and in some case up to 30%. The ratio of backscattering ratio and the aerosol color ratio are in teh range of 1-5 and 0.3-0.9 respectively. To identify the Asian dust, we retrieved the particle size distribution from the signals of 355nm and 532nm of MWA lidar. In the 12:35-12:40, March 21, 2000, the composition percentage of particle square distribution spectrum of small particles at 0.069-0.225 μm are higher value from 12-39%. Also large particles is lower that are about 17-19% at 0.752μm, 7% at 1.301 μm, and 5% at 2.355μm, respectively.
The study of backward trajectory carried out in this episode. The results coincide well with the lidar measurement profiles.
Asian-dust and Cirrus cloud have been measured by Multi-Wavelength aerosol lidar since 2000 and Automatic Controlled Aerosol lidar since 2002 at Suwon (127°E 37°N),Korea. These Lidars are Mie scattering scheme that use 355/532/1064 nm and 532 nm respectively. The vertical profiles of range corrected backscatter intensity and depolarization ratio on 16 days of Asian dust in springtime of 2002 are analyzed for this report. In Suwon, the Asiandust mainly showed at lower troposphere below 3 km but several cases showed in free troposphere of over 4 km. The peak depolarization ratios are in the range of 20-40%. The thickness of dust layer is about 2-2.5 km in case of lower tropospheric measurements. After event ofAsian dust the cirrus clouds are often measured in resemblance to Asian dust at upper troposphere. The maximum upper altitudes are about 8 to 12 km. The clouds falling down to about 3 km were measured which is a higher depolarization ratio of 10-30 %.
Asian dust have been measured by Multiwavelength lidar which supplied with three wavelengths (355, 532 and 1064 nm) laser and multimode receiver system. The system provides three modes of receiving system of Aerosol (355, 532 and 1064 nm), Raman (387, 408 and 355 nm) and Polarization (532 am) measurements. Six cases of Asian dust profiles from 5 km upto 12 km are achieved in spring of 2000. As the results, we can see the backscattering ratio of aerosol and Asian dust shows similar value that is in the range of 1.2 to 3, but the values of depolarization ratio is large that over 15% of Asian dust than below 10% of aerosol. Also, the concentration of large particle size over O.7O7tm is increased when in cases of Asian dust.
DIAL (Differential Absorption Lidars) method is being used as one of the most effective method to reduce the interference error from air density and aerosol in ozone measurement. But according to the selection of each wavelength, the optical parameters are much variable, and it sometimes bring the great error of ozone concentration. Especially aerosol optical parameters are strongly affected by the kinds and the concentration in stratosphere and troposphere[1,2].