Abstract:Based on the atmospheric refractive index structure constant (Cn2) observed by the boundary layer wind profile radar (WPR) of Jinan Station, the boundary layer height (HBL) during the daytime in summer is determined by the deviation degree method, whose results are compared with those by the dry adiabatic curve method based on L-band sounding data and the national standard method based on surface meteorological observations. The results are shown below. 1) The mean values of the daily maximum HBL in the 25 d determined by the three methods are 2 500.0 m, 2 529.1 m, and 2 469.9 m, respectively, which are generally consistent; the standard deviations (σ) between the results of deviation degree method and those of the latter two are 337.1 m and 636.7 m, respectively; the correlation coefficient (R) between the results by the first two methods is 0.668, while the R between the results by the two methods and those by the national standard method are -0.130 and -0.064, respectively, which confirms that the accuracy of mean HBL by the national standard method is acceptable but the accuracy of real-time HBL is low. 2) The average and most occurrence time of the daily maximum HBL determined by the deviation degree method are 15:00 during the 25 d and the HBL increases slowly from 07:00 to 15:00 and decreases rapidly from 15:00 to 19:00; however, the average and most occurrence time of the daily maximum HBLdetermined by the national standard method are 16:00 during the 25 d and the HBL collapses from 13:00 to 15:00, which is significantly different from the afternoon-peak pattern of the convective boundary layer. 3) The HBL determined by the first two methods has a good correlation with surface temperature and air temperature, but a poor correlation with wind speed; while the HBL determined by the national standard method has an opposite result. For the deviation degree method, the average response time of the daily maximum HBL to the highest air temperature and the highest surface temperature are about one h and two h, respectively, which accords with the response relationship and order of solar radiation-surface temperature-air temperature-HBL, but the daily maximum HBL by the national standard method fails to reflect this response. 4) The HBL by the deviation degree method has a significantly negative correlation with the hourly mass concentration of each pollutant, but the HBL by the national standard method has a poor correlation. 5) Through the comparison of these three methods, the HBL determined by the deviation degree method has higher accuracy to depict the spatio-temporal evolution; the dry adiabatic curve method has good accuracy but cannot give the spatio-temporal evolution; the national standard method has low accuracy of real-time HBL, and although it can give the spatio-temporal evolution, the deviation of the afternoon peak is large.