Large-eddy simulation of the planetary boundary layer under baroclinic conditions during daytime and sunset turbulence

This study investigates the Large-Eddy Simulation (LES) technique in the diurnally varying atmosphericboundary layer in conditions of realistic environmental forcing. The initial settings of meteorological fields are obtainedby 'ingesting' into the LES domain the vertical profiles of wind, temperature and specific humidity provided by themeteorological model WRF. The surface values of potential temperature and specific humidity from the WRF simulationare used as forcing parameters for the LES runs. These forcing parameters are updated during the runs every 1 h. Amethodology is developed to derive the components of the geostrophic wind profile that is used in LES to model the largescalehorizontal mean pressure gradient and treated as an external forcing. This methodology involves the meteorologicalmodel WRF. In this context, the WRF model has a dual task: (1) providing realistic atmospheric environmental forcings toLES and (2) providing a very large dataset to investigate possible improvements of the LES setting to make the numericalprediction more realistic.The principal results obtained by the present study is that the use of geostrophic wind shear profiles improves theprognostic capability of LES in reproducing the wind field pattern in the planetary boundary layer, this is an importantparameter for the proper description of the decay of the turbulent kinetic energy at sunset.