Comparison of the WRF and Sodar derived planetary boundary layer height

In this work, we compare the planetary boundary layer (PBL) height, calculated with the weather research and forecasting (WRF) model, with the measurements from an acoustic remote sounding system (Sodar) gathered at Wrocaw, SW Poland. The comparison was made for 15-30 November 2011. During this period, very high concentrations of PM2.5 were observed in SW Poland. For nine days, the 24-hour average PM2.5 concentrations reached the level 'unhealthy for sensitive groups' and for two days the 'unhealthy' level according to the air quality index. Four simulations were run with different PBL schemes for the innermost domain. The tested PBL schemes were: Yonsei University (sim1), Mellor-Yamada Nakanishi and Niino Level 3 (sim2), Asymmetric Convective Model 2 (sim3) and Bougeault-Lacarrère (sim4). The results show that all the schemes tested overestimate the PBL height, with the largest mean absolute errors for sim1 and sim2 (215 and 225 m, respectively). The mean error is significantly smaller for sim3 and sim4 (109 and 72 m, respectively). The agreement between the WRF and Sodar PBLH has a diurnal pattern and changes with the Pasquill stability classes. The overestimation of the PBL height might lead to the underestimation of air pollutant concentrations modelled with the air quality models.