Publication: Desarrollos de parametrizaciones urbanas y optimización del acoplamiento ciudad-atmósfera
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2016-02-18
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Universidad Complutense de Madrid
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Abstract
Las ciudades interaccionan con la atmósfera, produciéndose un aumento de la temperatura con respecto al medio rural circundante (Isla de calor) y una disminución de la velocidad del viento. Estos fenómenos pueden llegar a ocasionar problemas para la salud de la población, que cada vez mas, esta en aumento, en detrimento de la población que habita las zonas rurales. Con la idea de mejorar las condiciones de vida en las ciudades, la comprensión y caracterización del clima urbano, mediante la modelización atmósferica, se ha convertido en una herramienta necesaria. Con este propósito se han desarrollado las denominadas parametrizaciones urbanas, que representan, de forma promediada, el comportamiento de las variables meteorologicas dentro de la ciudad. Los objetivos de esta tesis son la mejora de la parametrización urbana BEP (Building Effect Parameterization, Martilli et al. 2002) implementada en el modelo de mesoescala WRF (Weather Research and Forecast model, Skamarock et al. 2008), y la optimizacion del acoplamiento de dichas parametrizaciones y el modelo atmosférico, con la finalidad de aumentar su resolución sin generar un coste computacional. En la primera parte de la tesis, se utilizan modelos numéricos de microescala para extraer la física para la parametrización urbana. Por un lado, se propone una parametrización para el coeficiente de arrastre, definido para calcular la fuerza de arrastre de los edificios sobre el viento, en función de las distancias entre edificios, en las direcciones paralela y perpendicular al viento, para configuraciones alineadas de edificios. Además, se extiende la fórmula presentada en Santiago y Martilli (2010) para las longitudes de escala involucradas en el transporte turbulento y en la disipación de la turbulencia, para dichas configuraciones de edificios. Ambas fórmulas son extraídas para condiciones de estratificación térmica neutra. Por otro lado, se proponen formulas para el cálculo de los parametros anteriores en el caso de una estratificación térmica inestable. Además, se estudia el flujo dispersivo, parametrizandolo, junto al flujo turbulento, mediante una extensión de la teoría K de Monin – Obukhov. En la segunda parte se presenta una nueva técnica para el acoplamiento del modelo de mesoescala y la parametrización urbana que permite un aumento de la resolución dentro de la subcapa rugosa, permitiendo una disminución de la resolucion vertical del modelo atmosférico y, por lo tanto, una disminución del tiempo de computación.
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.
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.
Description
Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Departamento de Física de la Tierra, Astronomía y Astrofísica I (Geofísica y Meteorología), leída el 08-01-2016