A New Determination Method Of Atmospheric Boundary Layer Height Based On Lidar And Case Analysis

The height of the boundary layer is an important factor to measure the development of the atmospheric boundary layer and the degree of air pollution,and an important parameter for environmental and climate research.The development of lidar detection system provides a very effective means for studying atmospheric boundary layer.This paper summarizes the previous methods and experience of retrieving the height of the atmospheric boundary layer based on lidar,and proposes a new method based on the use of lidar system to retrieve the height of the boundary layer.A comparative analysis of the development characteristics of the boundary layer structure during the weather.The main conclusions of this article are as follows:1.Using gradient method,standard deviation method,curve fitting method and stepwise curve fitting method to invert the backscatter data of the lidar system to obtain the height of the atmospheric boundary layer.Through the results,it concluded that the gradient method and the standard deviation method are limited to the noise of the original data;the curve fitting method needs to give the initial parameters according to the actual situation,and is not suitable for long-term observation.The stepwise curve fitting method improves the defect that the curve fitting method needs to debug the initial parameters according to the environment.This method is more suitable for long-term observation data by exhaustively enumerating all the heights that can become the atmospheric boundary layer as the initial fitting value,but this method has too high judgment for the data inversion of the sky background light noise.The situation appears.2.An important feature of the atmospheric boundary layer is that at the top of the boundary layer,there is a significant abrupt change in the vertical distribution of aerosol concentration.Taking advantage of this feature,using active remote sensing device to smooth out the data after window noise removal,an improved atmospheric boundary layer height inversion method based on gradient method-window standard deviation method is proposed.Based on the backscattering profile data of the laser ceilometer,this method is used to retrieve the height of the boundary layer,and the inversion results are ideal under the condition that the atmospheric aerosol is mixed evenly at the boundary layer height.On this basis,comparing the inversion results of the window standard deviation method with the inversion results of the stepwise curve fitting method,it is found that the two methods have a good correlation.The window standard deviation method can reduce the influence of high-altitude background light noise on the inversion results.After comparing with the inversion results of sounding data from Baoshan District,Shanghai,it is found that the inversion results are consistent with the structural characteristics of the urban boundary layer.The height of the boundary layer inverted by this method has the characteristics of strong continuity in time series,and the inversion results are more conducive to the study of the temporal change trend of the height of the atmospheric boundary layer.Based on the window standard deviation method and the idea of finding breakpoints by piecewise linear fitting,the article proposes another new method of atmospheric boundary layer inversion,piecewise linear fitting method.3.Using the June 2018 Shanghai Fengxian Laser Ceilometer data and August 2018 Shanghai Baoshan Lidar data,using the window standard deviation method to retrieve the boundary layer height;case analysis summarizes the law of atmospheric boundary layer height evolution during the sunny process,precipitation process and low vortex shear control process.