Evaluation of the Sensitivity of PBL and SGS Treatments in Different Flow Fields Using the WRF-LES at the Perdigão

This study has investigated the effectiveness of the large-eddy simulation version of the Weather Research and Forecasting Model (WRF-LES) in reproducing atmospheric conditions observed during the Perdigão field experiment. When comparing the results of the WRF-LES model with the observations, using LES settings can accurately repre-sent both large-scale events and the specific characteristics of atmospheric circulation at a small scale. Six sensitivity experiments are performed to evaluate the impact of different Planetary Boundary Layer (PBL) schemes, including the MYNN, YSU and Shin and Hong (SH) PBL models, as well as Large Eddy Simulation (LES) with Sma-gorinsky (SMAG), a 1.5-order turbulence kinetic energy closure model (TKE) and non-linear backscatter and anisotropy (NBA) subgrid-scale (SGS) stress models. Two case studies are selected to be representative of flow conditions. In the northeastern flow, the MYNN NBA simulation yielded the best result at a height of 100 m with an error rate of -0.03 m/s, although SH generally produces better results than PBL schemes. In the southwestern flow, MYNN 1.5 TKE simulation at station Mast 29 is the best result, with an error rate of -0.01 m/s. The choice of SGS models over complex terrain affects wind field features in the boundary layer more than above the boundary layer. The NBA model generally performed better results in complex terrain when compared to other SGS models. In general, the WRF-LES can model the observed flow with high-resolution topographic maps in complex terrain with different SGS models for both flow regimes.