In this study, we developed an integrated algorithm for determining the daytime PBLH from the attenuated backscatter at 532 nm.
If we introduce into the backscatter profile S(z), the convolution of Haar function h with S(z) is given by the following equation:
Because a strong negative gradient of backscatter is presented between the PBL and the free troposphere, the top of the PBL can be identified by searching for the local maximum in [W.sub.f](a,b).
Secondly, we chose all local maxima of the wavelet covariance coefficients that correspond to a maximum in the attenuated backscatter at 532 nm itself in the meantime.
Due to the sharp decrease in the vertical profile of backscattered signals between PBL top and free troposphere above, there is a local maximum in the vertical gradient of backscattered signals.
Due to the sharp gradient caused by the sharp increase in backscatter signal mentioned in Section 1, an improved maximum variance method was developed based on the technique by Jordan et al.
where [beta]' is the total attenuated backscatter at 532 nm and i is the position of the backscatter signal in vertical profiles of backscatter, which is corresponding to the currently local maximum of standard deviation that needed to be judged.
Figures 3(a) and 3(b) show the vertical profiles of total attenuated backscatter at 532 nm acquired, respectively, from CALIOP and CE370 on Lille site at 12:51 UTC (13:51 local time) on December 31, 2015.
Because CALIOP observes the atmosphere by looking downward from space, the clouds (especially the thick clouds) involve significant attenuation of the backscatter signal in underlying layers.
