Seasonal Variation of Aerosol Vertical Distributions in the Middle and Lower Troposphere in Beijing and Surrounding Area during Haze Periods Based on CALIPSO Observation

The data from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite was used to analyze the aerosol micro-physical properties over Beijing and surrounding area during haze periods from 2007 to 2008 in this paper. The results showed as follows. The values of TABC (total attenuated backscatter coefficient) for aerosols accounted for about 25% with varying altitudes. The aerosol scattering ability little changed from 0-4 km, showing that the aerosol layer evenly distribute. At different altitude ranges (0-1, 1-2, 2-3 and 3-4 km above ground level), values of TABC almost concentrate in the range of 2.5x10(-3) -4.5x10(-3) km(-1.)sr(-1). In spring, summer and winter, aerosol scattering has the similar variation, with the maximum of TABC ranging from 3.5x10(-3) km(-1.)sr(-1) to 4.5x10(-3) km(-1.)sr(-1), while the maximum of TABC in autumn is from 1.5x10(-3) km(-1.)sr(-1) to 2.5x10(-3) km(-1.)sr(-1). Aerosol shape and size are characterized by VDR (volume depolarization ratio) and TACR (total attenuated color ratio). Aerosols with VDR greater than 10% were more than the ones with VDR less than 10% at the same altitude range. Notably, aerosols with smaller VDR (0-10%) appeared more frequently in autumn than those in the other three seasons. For each altitude range, aerosols with TACR ranging from 0-0.2 contributed much more than those with TACR ranging from 1.8-2.0. The size of aerosols in summer was the largest and that in autumn was the smallest in middle and lower troposphere.