Preliminary Study On High-Spectral-Resolution Lidar Based On Iodine And Detection Of Atmospheric Boundary Laver Height

With the development of social economy and improvement of people's living standard,environmental pollution has drawn more and more attention.Atmospheric boundary layer(ABL)is the lowest part of troposphere,which is directly influenced by the Earth's surface.It is closely related to the energy and matter exchange between the free atmosphere and surface,and the distribution and diffusion of aerosol is decided by the turbulence in the ABL,therefore its height is an important feature of ABL.Not only does it declare the volume into which ground-based pollutants can disperse,but also the convective time scales present within ABL.Besides,the ABL height is a key parameter in climate models.Lidar has the advantages of high temporal and spatial resolution,all-time and all-weather operation and so on,so it is very suitable for the detection of ABL height and optical parameters of aerosol.Assumption of lidar ratio of atmosphere must be made when inversing the data of traditional Mie Lidar,so the accuracy is limited.In the recent years,technics such as Raman lidar and high-spectral-resolution lidar(HSRL)has become more popular because of the accurate data inversion.However,the Raman scattering is so weak that the detection ability is strongly limited.HSRL has good detection ability and range,so it is a very promising technic.HSRL performs high spectral resolution discrimination on the backscatter signal.Among so many kinds of spectral filter,the Iodine absorption cell is best at 532 nm yet because of the good filter ability,easy usage,stable operating characteristics and so on.A HSRL system was built and introduced in detailed parts based on the original polarized system,and primary experiments on the detection of ABL height were performed,whose results were great.In this paper,the meaning of aerosol and ABL height and the process in ABL height detection with lidar at home and abroad were firstly introduced;then,the principle of HSRL was introduced in detail,as well as the composition of every parts and the parameters choices of the built HSRL system.And then three commonly used ABL height inversion algorithms were introduced,and the performance of these three algorithm was compared during computer simulations,including gradient method,profile fitting method and wavelet covariance method.After that,the application of HSRL in the detection of ABLH was verified,which declared the advantages of HSRL above traditional Mie lidar in terms of ABLH detection.At last,the built lidar system was used to detect the ABL height from 9th to 10th,January,2018 over Hangzhou(30°16' N,120°07' E)area,and three algorithms were used to inverse the ABL height.The results proved the great accuracy and stability of the wavelet covariance method.And the inversion result was also in correspondence with the general changing pattern of ABL height,which proved the validation of lidar in detecting ABL height.The development of this HSRL system provides more accurate results for the detection of ABL height and optical parameters of aerosol,which has great significance in the research of ABL and aerosol,and it can provide data support and basis for the control of aerosol pollution.