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An intercomparison of long‐term planetary boundary layer heights retrieved from CALIPSO, ground‐based lidar, and radiosonde measurements over Hong Kong
Author(s) -
Su Tianning,
Li Jing,
Li Chengcai,
Xiang Pengzhan,
Lau Alexis KaiHon,
Guo Jianping,
Yang Dongwei,
Miao Yucong
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd025937
Subject(s) - lidar , radiosonde , environmental science , aerosol , planetary boundary layer , standard deviation , atmospheric sciences , boundary layer , meteorology , remote sensing , atmosphere (unit) , turbulence , geology , geography , physics , statistics , mathematics , thermodynamics
The planetary boundary layer height (PBLH) is a very important parameter in the atmosphere, because it determines the range where the most effective dispersion processes take place, and serves as a constraint on the vertical transport of heat, moisture, and pollutants. As the only space‐borne lidar, Cloud‐Aerosol Lidar with Orthogonal Polarization onboard Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) measures the vertical distribution of aerosol signals and thus offers the potential to retrieve large‐scale PBLH climatology. In this study, we explore different techniques for retrieving PBLH from CALIPSO measurements and validate the results against those obtained from ground‐based micropulse lidar (MPL) and radiosonde (RS) data over Hong Kong, where long‐term MPL and RS measurements are available. Two methods, namely maximum standard deviation (MSD) and wavelet covariance transform (WCT), are used to retrieve PBLH from CALIPSO. Results show that the RS‐ and MPL‐derived PBLHs share similar interannual variation and seasonality and can complement each other. Both MSD and WCT perform reasonably well compared with MPL/RS products, especially under sufficient aerosol loading. Uncertainties increase when aerosol loading is low and the CALIPSO signal consequently becomes noisier. Overall, CALIPSO captures the general PBLH seasonal variability over Hong Kong, despite a high bias in spring and a low bias in summer. The spring high bias is likely associated with elevated aerosol layers due to transport, while the summer low bias can be attributed to higher noise level associated with weaker aerosol signal.