Phonon-Induced Decoherence in Electron Evolution

tures from geographic information databases. The model outputs are: sun location in Cartesian coordinates; grid cells in shadow and sun; sky view factor in every grid cell; direct and diffuse partition; and finally, the total short wave radiation by each grid cell. Sky view factor and reflections are calculated using a three-dimensional ray tracking method. It consists in casting rays from an hemisphere located on the center of each grid cell and count the number of rays that collide with the buildings. In 1km× 1km model domain, around 35000-50000 rays are needed. It is a high demand computing process so it is implemented following a distributed memory parallel approach (Message Passing Interface MPI). Some details about the speed-up of the algorithm will be presented in this paper. Direct and diffuse radiation partition is made taking into account the solar zenith angle and the sky conditions (cloudless conditions or cover conditions). The direct radiation is affected by the shadow and diffuse by the sky view factor. The total short wave radiation by each grid cell is calculated by an iterative method. After an initial solar radiation map (ISR), m reflections are calculated until the increment is less than 1% of the ISR. The data produced by the urban solar radiation model has been used in large scale numerical experiments to simulate turbulent fluxes for urban areas, over Madrid (Spain) city. We have applied a modified version of the EULAG (UCAR) micro scale model (CFD) which includes an energy balance equation to obtain the urban energy exchange. Results of the micro scale simulations and how sensitivity are the results to the solar radiation approach will be presented in this paper.