13LIDAR Development of the Best Estimate Planetary Boundary Layer Height with ARM Ground-based Remote Sensing Measurements

Planetary boundary layer height (PBLHT) has been commonly determined from radiosonde data. The Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) PBLHT-SONDE Value-added Product (VAP) provides PBLHT estimation from radiosonde data using three methods: 1) the Heffter method; 2) the Liu-Liang method; and 3) the bulk Richardson method based on two critical thresholds of 0.25 and 0.5. However, radiosonde data suffers from poor temporal resolutions and is subject to sampling error. Lidar and radiometer remote sensing measurements offer high-temporal and continuous estimations of PBLHT. ARM provides various PBLHT estimations using remote sensing measurements, including: 1) PBLHT-CEIL from the VAISALA CL31 built-in software using an enhanced gradient method; 2) PBLHT-MPL from the wavelet covariance of Micro-pulse Lidar (MPL) backscatter profile (Sawyer and Li, 2013); 3) PBLHT-DL from the vertical velocity (W) variance measured by a Doppler Lidar using a threshold of 0.04 m^-2s^-2 (Tucker et al., 2016); 4) PBLHT-RL from Raman Lidar (RL) and (AERI) retrieved temperature and water vapor profiles using the Heffter method. Each remote sensing measurement has its own strength and limitation. To obtain reliable PBLHT estimations during the full day cycle and under different boundary layer conditions, we trained a random forest machine learning model to pick up the best estimate PBLHT (PBLHT-BE) from different remote sensing estimations. Results show that PBLHT-BE demonstrated improved correlations and better comparisons with PBLHT-SONDE. Feature importance analysis indicates that PBLHT-RL carries the most significant weight.

Reference:

Sawyer, V. and Li, Z.: Detection, variations and intercomparison of the planetary boundary layer depth from radiosonde, lidar and infrared spectrometer, Atmos. Environ., 79, 518–528, https://doi.org/10.1016/j.atmosenv.2013.07.019, 2013.

Tucker, S. C., Senff, C. J., Weickmann, A. M., Brewer, W. A., Banta, R. M., Sandberg, S. P., Law, D. C., and Hardesty, R. M.: Doppler lidar estimation of mixing height using turbulence, shear, and aerosol profiles, J. Atmos. Ocean. Tech., 26, 673–688, 2009.