Characteristics of the planetary boundary layer above Wuhan, China based on CALIPSO

Planetary boundary layer height (PBLH) has important implications for human health, weather forecasting, ecology, and climate change. This study aims to investigate the characteristics of the PBLH above Wuhan, China. We propose a new procedure (wavelet covariance and the ideal curve-fitting algorithm) to reveal PBLHs based on the Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observations (CALIPSO) attenuated backscatter ratio. Under cloud situation, the results of PBLHs revealed from CALIPSO show a relatively low correlation (R2 = 0.55) with PBLHs determined using a thermodynamic method. And the results show a significant correlation coefficient (R2 = 0.86) when the cloudy scenarios are eliminated. Because CALIPSO could have mistakenly classified cloud tops as PBLHs during the formation of stratocumulus clouds. Characteristics of annual and seasonal variations of the PBLH for all sky conditions from June 2006 to September 2013 were also studied. Because of the climatic and geographic characteristics of Wuhan City, the PBLHs display clear annual and seasonal variations. Warmer seasons have deeper PBLHs, while colder seasons are characterized by shallower PBLHs. Over 90% of daytime PBLHs in Wuhan are between 400 and 1800 m, while over 90% of nocturnal PBLHs clustered between 200 m and 1000 m. This research will contribute to improving PBLH input parameters for numerical models and enhance the understanding of the urban planetary boundary layer.