The Study On The Characteristics Of Aerosols Based On CALIPSO Signal Data

In this study, the level1and level2aerosol profile data basing on CALIPSO (Cloud-AerosolLidar and Infrared Pathfinder Satellite Observation) satellite was dealt to research the propertiesof local aerosol and the variation of Aerosol Optical Depth (AOD) across the country.Level1data of Tianjin from January to April2014was dealt primarily to analyze thedistribution of atmospheric aerosol with the depolarization ratio. Then the level2data was dealtas follows: firstly, the aerosol vertical distribution characteristics of Tianjin area were classified.According to their characteristics of extinction profile, them were classified into five differenttypes, and the most typical extinction profile of each type were listed. Secondly, AOD wascalculated based on the CALIPSO level2data by Matlab. Then a linear regression model wasconstructed, in which AOD is an independent variable and PM2.5is a dependent variable. All thedata were fit by the selected five functions: linear, logarithmic, exponential, power, and quadratic.Lastly, seven typical nationwide cities was selected, then the characteristics of AOD nearly sevenyears were analyzed, and the spatiotemporal evolution rules of AOD across the country wereobtained.It showed the results as follows: Firstly, there are a lot of irregular aerosol particles at analtitude of0.2km-4km and8km-10km in that period of Tianjin. All the results obtained inthe present study confirmed that the irregular aerosol particles at that altitude of0.2km-4kmmay highly related by the haze which appeared frequently at that period in Tianjin region, whilethe aerosol particles which occurred at the altitude of8km-10km may be caused by dust andvolume clouds. Secondly, Experimental results showed that the value of correlation coefficient ofthe quadratic equation model is the best one among the fitted equation of PM2.5and AOD.Furthermore, it showed that the calculated data have seasonal variation, which can be easilyobserved, and correlation of spring and summer was obviously higher than that of autumn andwinter. Thirdly, AOD of seven nationwide typical cities generally remains at a level between0.38to0.46in recent years and tends to increase. AOD trended appear low in northwest andnortheast area overall, while it appeared high in central and southern China. Meanwhile, thestudy found that there is a negative correlation between monthly average AOD and visibility,correlation of northwest and northeast China is higher than that of other area. And in central andsouthern region, correlation of autumn and winter is smaller, But spring and summer there is stillstay in observable negative relationship. Depending on all above studies, this experiment got the regularpatterns of correlation between aerosol optical properties and atmospheric changing,resulting aerosol optical properties will affect the changes in the atmosphere to some extent. Atthe same time, this study also illustrated that it is viable to study on atmosphere basing onCALIPSO data.