Preliminary Analysis Of Atmospheric Structure Characteristics Of Tropopause Bsae On Raman Lidar

The tropopause is a transitional layer between the troposphere and the stratosphere.It is one of the most basic structural features of the earth's atmosphere and a sensitive region of climate change caused by human activities.The coupling of tropospheric and stratospheric physical,chemical and radiative processes affects climate change directly.In particular,the change of tropopause structure,location and intensity directly affects the weather and air conditions in the surface boundary layer.Therefore,long-term fine observation and structural analysis of tropopause are of great scientific significance and application value for the study of the earth and the local climate and meteorological changes.Aiming at structure characteristics of tropopause in this thesis,on the basis of the multi-parameter simultaneous Raman lidar system and the traditional retrieval technique,a large-dynamic atmospheric temperature retrieval method based on vibration-rotational Raman lidar is designed.The temperature retrieval method by using N2 vibration Raman lidar is first studied,and splicing technique based on error weight of vibration-rotation Raman is combined to realize the accurate inversion of atmospheric temperature in the troposphere and lower stratosphere,the statistical temperature error is less than 3K below the height of 22km.An improved method for accurate inversion of atmospheric aerosol optical parameters based on backscatter ratio calibration is also proposed.Scattering ratio as a characteristic parameter,the effective detection for aerosol layer or cloud layer is achieved in the range of troposphere and lower stratosphere,which provides reliable technical support for the study of the tropopause atmosphere structure and data sources.By using lidar data from 2013 to 2015 obtained by atmospheric multi-parameter synchronous Raman lidar,a long-term data inversion and analysis has been carried out.The atmospheric temperature,aerosol optical parameters,water vapor density and relative humidity profiles were obtained in the troposphere and lower stratosphere.Combined with the NCEP data and the airflow trajectory from HYSPLIT model,the diurnal and seasonal variations in atmospheric multi-parameters were investigated in the tropopause region over Xi'an.Via synchronous analysis of atmospheric multi-parameter,the results show that the tropopause height over Xi'an area is within the range of 17-18.5km.The aerosol layer is easily formed near the tropopause with obvious increase of backscatter ratio,and sudden decrease in relative humidity and wind speed is also accompanied.Also,the rapid airflow trajectory from west or northwest is the main origin.And thus,an exploratory analysis of structure characteristics of tropopause is realized in Xi'an.