Performance of PALM-4U/WRF model for simulating the urban meteorology of King Abdullah University of Science and Technology (KAUST), Saudi Arabia

This study evaluates the performance of the PALM-4U model nested within the WRF mesoscale model (with and without the chemistry module coupling, WRF-Chem) for simulating air temperature, humidity, and wind speed at 2 m in the semi-urban region of the King Abdullah University of Science and Technology (KAUST), Kingdom of Saudi Arabia (KSA). Microscale simulations were conducted using PALM-4U for two typical days (one day in summer and one day in winter) based on the boundary and initial conditions from WRF and WRF-Chem models for both meteorological and soil parameters. The model's performance was evaluated using measurements available at two weather stations in the study domain. The simulations indicate that PALM-4U performs better when driven by WRF-Chem outputs with global initialization from ERA5 in summer and NCEP-FNL in winter. The results also suggest that PALM-4U performs markedly better than WRF and WRF-Chem in simulating temperature and relative humidity at the KAUST urban scale in both summer and winter based on the overall error metric.