Determination of the boundary layer top from lidar backscatter profiles using a Haar wavelet method over Wuhan, China

The boundary layer (BL) is a lower layer of the atmosphere that is directly influenced by the Earth's surface and responds to surface forcing. In this study, a Mie lidar (light detection and ranging) system was utilized to measure the boundary layer over Wuhan, China. We employed the Haar wavelet covariance transform (WCT) method to find the boundary layer top to our lidar dataset. We thoroughly analyzed the well-mixed case and cases involving cloud droplets and pollution aerosols that were detected above, within and below the entrainment zone. In addition, the primary results indicate that the WCT method based on the parameters selected we can detect the BL top and the cloud base of a profile automatically, effectively and accurately, of which the entrainment zone is not concealed by an optical thick layer. Therefore, a general pattern can be concluded after a long-term monitoring is completed in the future. Furthermore, the BL top exhibits nearly a real-time feedback to cloud existence.

► We employed the Haar wavelet method to find the boundary layer top.
► We thoroughly analyzed the well-mixed and contaminated cases.
► The approach can detect BL top and cloud base accurately.
► The BL top exhibits nearly a real-time feedback to cloud existence.