Desarrollo de Parametrizaciones urbanas y optimización del acoplamiento ciudad-atmosfera

Abstract

Cities interact with the atmosphere, generating an increase of temperature respect to the rural sourrounding area (Urban heat Island) and a decrease of the wind speed. This phenomena can produce health problems on the population, which is increasig, due to the decrease of the rural population. In order to improve the quality of living inside the cities, the understanding and characterization of the urban climate, by means of atmospheric modeling has become necessary. For this purpose, the so called urban canopy parameterizations have been developed, which represent, in an averaged way, the behaviour of the meteorological variables within the city. The objectives of this thesis are the improvement of the urban parameterization BEP (Building Effect Parameterization, Martilli et al. 2002) implemented in the WRF mesoscale model (Weather Research and Forecast model, Skamarock et al. 2008), and the optimization of the urban parameterization and the atmospheric model coupling, in order to increase its resolution without computational cost. In the first part of the thesis, microscale numerical models are used in order to extract the physiscs for the urban parameterization. From one side, a parameterization for the drag coefficient is proposed, defined in order to calculate the drag force on the wind speed produced by the buildings, by means of the distance between them, in the direction parallel and perpendicular to the flow, for aligned configurations. In addition, the parameterization of the length scales for turbulent transport and turbulence dissipation presented in Santiago and Martilli (2010) is extended. Both parameterizations are extracted for neutral thermal conditions. On the other side, parameterizations of the previous parameters are proposed, for unstable thermal conditions. In addition, the dispersive flux is studied and parameterized with the turbulent flux, by an extension of the Monin – Obukhov K- theory. In the second part of the thesis, a new technique to couple the mesoscale model and the urban parameterization is presented, which allows an increase of the resolution within the roughness sublayer, allowing a decrease of the vertical resolution of the atmospheric model, and thus, a decrease of the computational time.

Date of Award	2016
Original language	English
Awarding Institution	Universidad Complutense (Madrid)