Improved two-wavelength Lidar algorithm for retrieving atmospheric boundary layer height

Abstract The atmospheric boundary layer height (BLH) is a critical parameter for the spread and dispersion of atmospheric pollutants. We propose an improved two-wavelength Lidar algorithm for retrieving the BLH based on particle clustering. The algorithm was improved from two aspects: sample sequence selection and classifier optimisation. The backscatter coefficient and color ratio were chosen for the sample sequence construction, and Gaussian mixture models were used for the sample sequence classification. The improved method was tested on different real cases and compared with radiosonde measurements. The experimental results demonstrated the viability of the algorithm under weak mixing conditions, which can be problematic for prior methods. In addition, Lidar data from June 2015 to June 2016 were collected to investigate the stability of the improved method. The correlation between the BLH retrieved using the improved algorithm and that from the radiosonde measurements was R2 = 0.92, with an RMSE of 170 m. The correlation between the two-wavelength Lidar algorithm and radiosonde measurements was R2 = 0.82, with an RMSE of 180 m. The results show that the improved algorithm can obtain the BLH effectively and stability.

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