Automated Detection of the Planetary Boundary Layer Height and Cloud in Qingdao Based on Morphological Processing

Abstract

Clouds have double functions for lidar: Noise and useful information. In this study, the clouds were separated from temporal-spatial coherent Doppler wind lidar with a high temporal resolution image based on the morphological open filter, which produced a filtered image and a cloud image. First, the wavelet covariance transform was employed for the filtered image to retrieve planetary boundary layer height (PBLH) including surface layer height and mixed layer height. Then, the Savitzky-Golay filter with different time-window widths was applied for temporally multiscale analysis of PBLH's features,which related to temperature and humidity. Last, the areas of cloud image were estimated and related to specification rain water content in clouds. The results show that the proposed method is effective and stable for automatic detection of PBLH and cloud using only a single lidar, which was verified by the data of Qingdao in China.

Keywords

• Coherent Doppler wind lidar (CDWL)
• morphological opening filter
• planetary boundary layer (PBL)
• specification rain water content (SRWC)
• wavelet covariance transform (WCT)