Development and implementation of a column version of an Urban Canopy Parameterization in WRF and testing over Madrid

An improved version of the Urban Canopy Parametrization BEP, (Building Effect Parametrization Martilli et al., Boundary-layer Meteorology, 2002) has been developed and implemented in the WRF model. In this new version, conservation equations of momentum, heat and turbulent kinetic energy are solved in a vertical column up to 2-3 times the mean building height, with a high spatial resolution (few meters). In this column the exchanges of heat and momentum between the building surfaces and the atmosphere are considered. In this framework the mesoscale model forces the column model from the top, while the column provide the heat and momentum fluxes to the mesoscale model. Concerning the physics, a new parameterization for the drag coefficient and the length scales involved in turbulent transport and turbulence dissipation is also incorporated, allowing the distinguishing of different configurations of buildings. The advantage of this approach is to allow high resolution vertical profiles of the mean flow variables, like wind, temperature and turbulent kinetic energy, within the canopy and just above, without the need to have very fine vertical resolution in the mesoscale model. This will reduce the computational time, without reducing the accuracy, and allowing to run the code for longer periods. This new version of the urban scheme has been tested over the city of Madrid.