Understanding the Major Impact of Planetary Boundary Layer Schemes on Simulation of Vertical Wind Structure

Abstract

The structure and evolution of the atmospheric planetary boundary layer (PBL) plays an important role in the physical and chemical processes of cloud–radiation interaction, vertical mixing and pollutant transport in the atmosphere. The PBL parameterization scheme describes the vertical transport of atmospheric momentum, heat, water vapor and other physical quantities in the boundary layer. The accuracy of wind field simulation and prediction is one of the most significant parameters in the field of atmospheric science and wind energy. Limited by the observation data, there are few studies on wind energy development. A 3D Doppler wind LiDAR (DWL) providing the high-vertical-resolution wind data over the urban complex underlying surface in February 2018 was employed to systematically evaluate the accuracy of vertical wind field simulation for the first time. 11 PBL schemes of the Weather Research and Forecasting Model (WRF) were employed in simulation. The model results were evaluated in groups separated by weather (sunny days, hazy days and windy days), observation height layers of wind field, and various observation wind speeds. Among these factors, the simulation accuracy is most closely related to the observation height layers of wind field. The simulation is fairly accurate at a height of 1000–2000 m, as most of the relative mean biases for wind speed and wind direction are less than 20% and 6% respectively. Below 1000 m, the wind speed and direction biases are about 30–150% m·s−1 and 6–30%, respectively. Moreover, when the observed wind speed was lower than 5 m·s−1, the biases were usually large, and the wind speed relative mean bias reaches up to 50–300%. In addition, the accuracy of the simulated wind profile is better in the range of 10–15 m·s−1 than other speed ranges, and is better above 1000 m than below 1000 m in the boundary layer. We see that the WRF boundary layer schemes have different applicabilities to different weather conditions. The WRF boundary layer schemes have significant differences in wind field simulations, with larger error under the complex topographies. A PBL scheme is not likely to maintain its advantages in the long term under different conditions including altitude and weather conditions.

Modelling the European wind-blown dust emissions and their impact on PM concentrations

“…This strong overestimation is a known feature of the BouLac PBL scheme used in this study and others reported similar overestimation of wind speed (e.g. Tyagi et al, 2018;Zhang et al, 2021). As dust emissions scale non-linearly with wind speed that are above a threshold (Leung et al, 2022) this raises the potential to overestimate dust emissions if winds are overestimated.…”

Performance Evaluation of Planetary Boundary Layer Schemes in Simulating Structures of Wintertime Lower Troposphere in Seoul Using One-Hour Interval Radiosonde Observation

“…The magnitude of the 10-m wind speed increase from 1000 LST on 18 January was larger in the four simulations than in the observations. The wind speed decrease in urban areas due to buildings was not well-represented in the numerical simulations, similar to other numerical simulations [28][29][30]. At 925 and 850 hPa, the general tendencies of the simulated air temperatures in the four simulations reproduced those in the radiosonde observation.…”

High-Resolution Remote Sensing of the Gradient Richardson Number in a Megacity Boundary Layer

“…The microwave radiometer (HATPRO-G5, RPG, Meckenheim, Germany) is a passive microwave remote sensing device that can continuously acquire atmospheric thermal parameters such as temperature and humidity in the vertical range of 0-10 km in real time [18]. The microwave radiometer has two receivers, including seven frequency channels for water-vapor absorption lines (K-band 22.24-31.40 GHz) and seven frequency channels for oxygen absorption lines (V-band 51.26-58.00 GHz).…”