A new method to retrieve the diurnal variability of planetary boundary layer height from lidar under different thermodynamic stability conditions

• Published in: Remote sensing of environment 2020-02, Vol.237 (C), p.111519, Article 111519
• Main Authors: Su, Tianning, Li, Zhanqing, Kahn, Ralph
• Format: Article
• Language: English
• Subjects: Aerosols; Atmospheric stability; Backscatter; Backscattering; Boundary layer evolution; Boundary layer height; Boundary layer stability; Boundary layers; Convection; Diurnal variations; Earth Resources And Remote Sensing; Free convection; Lidar; Lower atmosphere; Planetary boundary layer; Planetary boundary layer height; Pollutants; Pollution levels; Radiosondes; Stability; Temporal variations; Thermal convection; Thermodynamic stability; Tracking; Wavelet analysis
• ISSN: 0034-4257; 1879-0704
• DOI: 10.1016/j.rse.2019.111519

The planetary boundary layer height (PBLH) is an important parameter for understanding the accumulation of pollutants and the dynamics of the lower atmosphere. Lidar has been used for tracking the evolution of PBLH by using aerosol backscatter as a tracer, assuming aerosol is generally well-mixed in the PBL; however, the validity of this assumption actually varies with atmospheric stability. This is demonstrated here for stable boundary layers (SBL), neutral boundary layers (NBL), and convective boundary layers (CBL) using an 8-year dataset of micropulse lidar (MPL) and radiosonde (RS) measurements at the ARM Southern Great Plains, and MPL at the GSFC site. Due to weak thermal convection and complex aerosol stratification, traditional gradient and wavelet methods can have difficulty capturing the diurnal PBLH variations in the morning and forenoon, as well as under stable conditions generally. A new method is developed that combines lidar-measured aerosol backscatter with a stability dependent model of PBLH temporal variation (DTDS). The latter helps “recalibrate” the PBLH in the presence of a residual aerosol layer that does not change in harmony with PBL diurnal variation. The hybrid method offers significantly improved PBLH detection, with better correlation and smaller biases, under most thermodynamic conditions, especially for SBL and CBL. Relying on the physical process of PBL diurnal development, different schemes are developed for growing, maintenance, and decaying periods. Comprehensive evaluation of this new method shows much better tracking of diurnal PBLH variation and significantly smaller biases under various pollution levels. •A lidar-based algorithm retrieving planetary boundary layer height was developed.•This method was evaluated in detail under various thermodynamic stabilities.•This method showed a great improvement for the stable boundary layer.•The biases were largely reduced under various stabilities and pollution levels.