Vertical Distribution Of Atmospheric Aerosol Optical Properties On The North China Plain

At present, the spaceborne Lidar has become a powerful tool to observe aerosol, compared with the traditional detection mode, it has a wide range of continuous observation, a high vertical resolution and measuring accuracy. It is rapid, real-time and long-term to detect of atmospheric aerosol optical properties and morphological features in both marine and terrestrial over the global. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) can be derived from systematical long term observational data, which can provide elemental data for the simulation of aerosol impacts on the climate. These statistical characteristics are important to the study of aerosol radiative forcing and furthermore climate change. In this paper, the vertical distribution of aerosol optical properties, including attenuated backscatter coefficient, volume depolarization ratio and color ratio during haze days on the North China Plain (NCP)(34.00°N～41.00°N,114.00°E～120.00°E) are analyzed by combined using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data from June2006to Dec.2013. Aerosol Robotic Network (AERONET) data, ground meteorological observation data and Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results are summarized as follows:(1) Between2006and2013, the mean value of attenuated backscatter coefficient in the range of4-8km height continued to decrease, while the average attenuated backscatter coefficient in the range of0-4km height was growing. It shows the aerosol scattering effect of the near-surface layers (0-2km) is increasing after2010, the aerosol scattering effect of high-rise (4-8km) decreased, it is related to the increasing haze weather (particles mainly gathered in the near surface layer) and decreasing dust weather (dust aerosol layers often exist in the range of4-8km height) in recent years.(2) Between2006and2013, the mean value of attenuated backscatter coefficient in the range of4-8km height in winter were maximum, it was related to the increased surface combustion emissions in NCP in winter. The average attenuated backscatter coefficient in the range of4-8km height in spring and winter were greater; the average attenuated backscatter coefficient in the range of0-8km height in summer were minimal. It means that the aerosol scattering mainly contribution to the upper troposphere which is in the range of4-8km height in spring and autumn. The high backscatter coefficient of upper troposphere was associated with the frequent dust weather in spring in NCP; the high backscatter coefficient of upper troposphere was associated with the biomass burning in harvest autumn in NCP.(3) After2008, the mean value of volume depolarization ratios in the range of2-8km height continued to decrease year by year, which shows rule spherical aerosol particles have increased in recent years. The lower atmosphere in the range of0-4km height is slowly increasing after2009. However the mean value of volume depolarization ratios in the range of6-8km height has been reduced after2008, which indicates the aerosol particle size of the upper troposphere is reducing, this is also consistent with increasing haze weather and decreasing dust weather in recent years.(4) The mean value of volume depolarization ratios and color ratio in the range of0-8km height are both maximum in spring and minimum in spring. And volume depolarization ratios increases with height. Which shows the spring is influenced by dust weather in NCP, irregularly coarse-particle aerosols of up. The mean value of volume depolarization ratios and color ratio in the surface layer (0-2km) in summer and winter are slightly larger than that in the range of2-4km height. Mainly aerosol emissions are from human activities in summer and winter, it is not only addition to automobile exhaust emissions and industrial emissions in winter, but also heating to increase emissions. The surface layer is easily affected by human activity to mix some irregular aerosols.(5) The lowest troposphere (<2km) was polluted most severely during the haze days on the NCP in2013. The total attenuated backscatter coefficient increased to0.0045km-1sr-1and volume depolarization ratios were greater than20%on the heavy haze day, Jan,2013. The color ratio>1accounted for about36.3%in0-8km height range on Jan.29, which suggested that aerosols during the heavy haze day are a mixture of a large number of fine particles and irregular coarse particles; The airflow carrying coarse mode particles from Siberia via Mongolia and China’s Inner Mongolia region can affect the haze weather and form haze aerosol pollution of the coarse and fine mode aerosols mixture on the NCP.(6) The AERONET aerosol products and HYSPLIT model simulation results are shown three haze pollution in NCP have not only dominated by anthropogenic fine particulate aerosols, also accompanied by coarse-particle aerosols. Remote sand-dust aerosol transport affects the composition of haze aerosol.