Columnar Aerosol Properties In Kunming Retrieved By Ground-based CE318 Sun-Photometer Measurements

In this paper,Sun and sky radiance measurements of Kunming station(25.063°N,102.707°E,Altitude 1926±7m)from March 2012 to February 2014 were used to retrieve columnar aerosol optical properties,which contain Aerosol Optical Depth(AOD),Angstrom Wavelength Exponent,Size Distribution,Complex Refractive Index,Single Scattering Albedo and so on.The measurements were obtained from the CE318 automatic Sunphotometer in Kunming observation sites.Then combined with the statistical methods,seasonal variations of columnar aerosol properties could be calculated and analyzed.The main conclusions were as follows:(1)Aerosol optical depth was reduced with increase of wavelength,which has the obvious characteristics of Mie Scattering.The seasonal variations of AOD in Kunming fluctuated in a single peak,which concrete showed as the AOD in summer keeping largest,followed by spring,autumn and winter.The value of AOD was suffered a tremendous influence from human factor,such as:vehicle emissions,municipal engineering and nndustrial waste gas.(2)With analysis of the Angstrom wavelength exponent,we could get the conclusion that types of aerosol in Kunming mainly consists of continental aerosol,urban-industrial aerosol and biomass burning aerosol.Sea salt aerosol content would increase because the air of the Indian Ocean in summer.(3)Aerosol size distribution in Kunming showed a distinctly bimodal distribution,of which the main peak value is near 0.2μm,and the secondary peak value is near 4μm.This conclusion is similar to the mode of continental aerosol and urban-industrial aerosol.At the same time,the change of each season also showed an approximate bimodal change trend,and the volume concentration of aerosols reached the maximum in summer.(4)According to the inversion results of complex refractive index and single scattering albedo(SSA),the real part of the complex refractive index got to the maximum value in summer,the smallest value in the winter,while the imaginary part was the opposite trend.The changes of SSA were as same as the real part.It indicated that the scattering ability of aerosol particles in summer was strong,while the absorption capacity was relatively weak,and the winter is just the opposite.