Measurements Of Cirrus Cloud And Dust Aerosol Using Lidar Over Semi-arid Areas

Cirrus and dust aerosol play significant roles in the radiative balance of the atmospheric system and affect the Earth's climate change. We still can not quantify the radiative forcing of them because the lacking of measurements. The measurements and analysis of cirrus and dust aerosols are made using lidar at Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL).(1) By using cirrus measurements with a Micro Pulse Lidar (MPL-4B) at Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) from April to November in 2007, the statistical analysis is made for cirrus height and thickness and the optical depth is calculated. The results show that the mean value of the cirrus height is 10.16±1.32 km above sea level. Cirrus thickness varies between 0.3 and 2.8 km, and the mean value is 1.10±0.49 km. Cirrus optical depth varies between 0.003 and 1.057, and the mean value is 0.17±0.16.(2) The vertical profile and size distribution are analyzed of the dust event on Mar 16,2010, and the meteorological data are also measured. The results show that the dust aerosols mainly exist below the boundary layer height. The change of dust and wind shows good correlation, and the change of wind begins before dust. The high value of fine mode particles is measured before the dust event, and the peak size is 0.7μm. The coarse mode particles significantly increase after the dust event beginning. There are still some non-sphere fine particles after the dust event.(3) The elevated dust layer is measured by polarization lidar and the origin of the dust is concluded through HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results show that the elevated dust measured at 2-3km is transported from Taklamakan Desert on Mar 22,2010.