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Mouzourides P.,University of Cyprus | Kyprianou A.,University of Cyprus | Brown M.J.,Los Alamos National Laboratory | Carissimo B.,Teaching and Research Center in Atmospheric Environment | And 2 more authors.
Urban Climate | Year: 2014

Mesoscale meteorological models rely on urban building datasets in order to determine several urban canopy parameters, such as the urban surface cover and morphological parameters, for accurate predictions of air quality and atmospheric pollution dispersion. Due to the multi-scale nature of air pollution dispersion, such models are run at various resolutions, and therefore grid sizes, in order to reflect the scale of observation and desired outputs. In this paper, a novel methodology, the Multi-Resolution Analysis (MRA), is applied to the urban building datasets of a number of European and North-American cities in order to obtain rigorously scale-adaptive spatially-varying representations of the different urban datasets.In the context of MRA, the urban-building information signal is analysed at different levels that each corresponds to a different scale. At each level the urban signal depicting a city is decomposed into an approximation, a representation at the scale that corresponds to the level, and a detail that is the part removed from the previous level that corresponds to lower scale. One of the major capacities and outputs of the MRA application is the multi-scale representation of the urban information while not losing the ability to recover the original density of urban information due to the tracking of the details. In this paper the results of such an MRA analysis of urban building datasets of European cities (London, Marseille and Nicosia) and North-American cities (New York City, Phoenix and Seattle as well as Oklahoma) are presented; the analysis provides consistent gridded and scaled attributes as well as sub-grid information for a hierarchy of grid sizes, for example used in nested urban simulations. Moreover, through the rigorous scale-adaptive spatially-varying representations that are obtained, a sound basis for consistent inter-comparisons is enabled. Finally, the paper illustrates how the MRA can provide an innovative means to perform analyses and provide unique scale-adaptive descriptions of any urban area - in essence a DNA-like description of a city. © 2014 Elsevier B.V.

Qu Y.,Teaching and Research Center in Atmospheric Environment | Milliez M.,Teaching and Research Center in Atmospheric Environment | Musson-Genon L.,Teaching and Research Center in Atmospheric Environment | Carissimo B.,Teaching and Research Center in Atmospheric Environment
Journal of Applied Meteorology and Climatology | Year: 2011

In many micrometeorological studies with computational fluid dynamics, building-resolving models usually assume a neutral atmosphere. Nevertheless, urban radiative transfers play an important role because of their influence on the energy budget. To take into account atmospheric radiation and the thermal effects of the buildings in simulations of atmospheric flow and pollutant dispersion in urban areas, a three-dimensional (3D) atmospheric radiative scheme has been developed in the atmospheric module of the Code_Saturne 3D computational fluid dynamic model. On the basis of the discrete ordinate method, the radiative model solves the radiative transfer equation in a semitransparent medium for complex geometries. The spatial mesh discretization is the same as the one used for the dynamics. This paper describes ongoing work with the development of this model. The radiative scheme was previously validated with idealized cases. Here, results of the full coupling of the radiative and thermal schemes with the 3D dynamical model are presented and are compared with measurements from the Mock Urban Setting Test (MUST) and with simpler modeling approaches found in the literature. The model is able to globally reproduce the differences in diurnal evolution of the surface temperatures of the different walls and roof. The inhomogeneous wall temperature is only seen when using the 3D dynamical model for the convective scheme. © 2011 American Meteorological Society.

Duraisamy V.J.,Teaching and Research Center in Atmospheric Environment | Dupont E.,Teaching and Research Center in Atmospheric Environment | Carissimo B.,Teaching and Research Center in Atmospheric Environment
Journal of Physics: Conference Series | Year: 2014

The main objective of this research work is to develop and evaluate several coupling methods between operational Numerical Weather Prediction (NWP) model and Computational Fluid Dynamics (CFD) model and data assimilate the field measurements into the CFD model. To address the problem of high spatial variation of the topography on the domain lateral boundaries between NWP and CFD domain boundaries, 3 methods-translation, extrapolation and Cressman interpolation are used to impose the NWP model data on the CFD domain lateral boundaries. Newtonian relaxation data assimilation technique is used to incorporate the field measurement data into the CFD simulations. These techniques are studied in a complex site located in southern France. Comparison of wind profiles between the CFD simulation, measurements and CFD simulation with data assimilation are discussed. This combination of state-of-the-art techniques in NWP, CFD, and field data assimilation will provide the basis of a more accurate wind resource assessment method. © Published under licence by IOP Publishing Ltd.

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