Numerical Simulation of Diurnal Planetary Boundary Layer Effects and Diurnal Mountain-Wind Effects

Abstract: The Weather Research and Forecasting Model was used to study its accuracy and representation in modelling a study area within a complex wind system as well as the effects on the model when using different input data and physics schemes. The complex wind system consists of diurnal mesoscale effects from the nearby Pyrenees mountain range and diurnal effects from the planetary boundary layer. A total of six different simulations were performed. The model was able to represent the study area but the results could be improved as there were inaccuracies in wind speed and wind direction associated with the planetary boundary layer. The model was especially challenged at predicting the wind speed and wind direction in the layer from the top of the planetary boundary layer to few hundred meters above it. The comparisons based on planetary boundary layer height is however complicated by the fact that there are different definitions in effect. The choice of model physics schemes and input data led to some differences in the results and warrants consideration when conducting similar simulations.