Simulation of turbulence in the atmospheric boundary layer (ABL) is made difficult by the large range of scales of the turbulent motions. To manage this, a model needs to use efficient numerical methods which are flexible enough to be able to handle realistic scenarios in the atmosphere. In this project, we are developing a new large eddy simulation model to be used for high resolution simulations of transient states in the ABL. The project has two parts: first, the developed model will be tested on canonical, quasi-stationary boundary layers to ensure good performance; and second, we will simulate a full diurnal cycle including transitions between nighttime and daytime boundary layers.