Abstract: Based on the data of boundary layer wind profile radar (WPR) at Ji'nan station,the technical difficulties in determining the height of the convective boundary layer (hereinafter referred to as CBLH) using the structure constant of atmospheric refractive index (hereinafter referred to as C_n²) were studied.Through transforming the profile of C_n² data to highlight its variable characteristics,we proposed a method to determine CBLH,namely,the deviation method based on an e-index fitting curve.Confirmed by case analysis and compared with the measurements,the results derived using this method are generally consistent with those derived using the methods of the L-sounding virtual potential temperature gradient and the moisture gradient.The correlation coefficients between the results obtained in this study and those obtained from the other two methods reach 0.988 and 0.980,respectively,and the average differences are +10.4 m and -21.8 m,the minimum differences are -70 m and-120 m,and the maximum differences are +50 m and +80 m,respectively.The comparison results of different methods show that,among thirty-one groups of samples, the results from seven groups derived by the maximum value method are significant differences from those derived by the deviation and the virtual potential temperature gradient methods.The deviation method is generally superior to the maximum value method in determining CBLH.This method can reduce the absolute error of CBLH in summer to approximately the level of the WPR vertical resolution.

Key words: Deviation degree method, Convective boundary layer height, Structure constant of atmospheric refractive index, Wind profile radar, L-sounding, Quality control