Research On The Feature Detection Algorithms And The Vertical Aerosol Optical Characteristics In China Based On The Spaceborne Lidar Data

The earth's atmosphere,clouds and aerosols in the atmosphere system plays an important role,not only affects to enrage radiation balance to influence the environment and climate change,and are closely linked with human body health.The influence of aerosol distribution on climate environment,radiation transmission,aerosol concentration and optical properties are the hot issues in the current research.At present,there are many methods for detecting clouds and aerosols in the atmosphere.The main detection methods are ground detection and passive remote sensing.The former obtains the cloud distribution for the small scope and the latter gets the column concentration information.The vertical distribution and optical properties of cloud and aerosol can not be obtained effectively in the atmosphere.The spacebome Lidar can make up the data that is difficult to obtain.From the perspective of CALIPSO data processing and algorithm realization,this paper realizes the detect of cloud and aerosol characteristics in the vertical direction of the atmosphere.In addition,using CALIOP data to verify the data of RAMS-CMAQ model,the aerosol optical characteristics of aerosol in the parallel and vertical direction of China in 2013-2015 were analyzed.First of all,this paper realizes the feature detection and layer properties algorithms based on CALIOP level 1B data.The vertical characteristics of cloud and aerosol are detected by threshold method,including single-profile scanning method and selective iterated boundary location method.For the strong feature layer,the method of single profile scanning is used.The feature value which greater than the threshold is located,and the threshold value will be updated through the feature penetration rate until the profile feature retrieval is completed.For the weak aerosol feature layer,the background noise is weakened by means of multiple profiles.On the basis of removing the detected features and improving the signal strength under the features of the removal feature,the method of iterative lookup is used to scan the search multiple time.The results obtained are compared with the official products,and the overall matching degree is good,but the accuracy of weak feature search needs to be improved.Secondly,this paper uses CALIOP data from 2013-2015 to verify the vertical characteristics of the RAMS-CMAQ atmospheric pattern data,and combines the two data to analyze the vertical optical characteristics of aerosol in China.The specific work is as follows:(1)The data reliability of CALIOP and RAMS-CMAQ was verified by using the ground-based AERONET site data.RAMS-CMAQ has a high correlation with site data,and the R value of correlation coefficient is 0.69.The R value of correlation coefficient between CALIOP and AERONET was 0.5.(2)We verified the correlation about the aerosol optical thickness between the CALIOP retrieved and RAMS-CMAQ simulated in China.Due to the differences in relative humidity and water-soluble aerosol concentration in different regions,the simulation results of RAMS-CMAQ were underestimated in the northwest of China and overestimated in the eastern plain and basin regions.(3)A comparative study was carried out on both the vertical aerosol extinction aerosol extinction coefficient profiles and the cross sections.The peak area of extinction coefficient in China is concentrated in the area under 0.5km,and the extinction coefficient of aerosol decreases with the height.In general,the simulation results of RAMS-CMAQ can be used as a supplement to the observation data and can be applied to the environment changes and air pollution monitoring in China.