Modelización de riesgos climáticos y sistemas de vigilancia y alerta en la Comunitat Valenciana

El primer objetivo de esta Tesis está relacionado con el desarrollo e implementación de diferentes sistemas de vigilancia y alerta para el territorio de la Comunitat Valenciana: un sistema de predicción meteorológica en tiempo real basado en el modelo atmosférico de mesoescala Regional Atmospheric Modeling System (RAMS) y un sistema de previsión del Índice UV (UVI), basado en el modelo Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART). Además, se propone una metodología que proporciona un entorno computacional adecuado para la administración y coordinación de los diferentes procesos implicados en ambos sistemas de vigilancia. La principal mejora de la predicción UVI es la utilización de datos de ozono total en columna obtenidos del modelo Global Forecast System (GFS), en lugar de los datos derivados del Ozone Monitoring Instrument (OMI) empleados en el sistema original. La validación de los resultados obtenidos por el sistema de predicción del UVI, para el año 2008, muestra un alto grado de acuerdo entre la modelización y la observación, teniendo en cuenta una diferencia del UVI de una unidad. Asimismo, la utilización de ozono total en columna correspondiente al modelo GFS presenta una ligera mejora con respecto a la previsión obtenida con el sistema original. El segundo objetivo que plantea esta Tesis está relacionado con la modelización de riesgos climáticos típicos en la Comunitat Valenciana. Para ello, se ha seleccionado un episodio reciente de lluvias intensas, que tuvo lugar los días 11 y 12 de Octubre de 2007. Utilizando este evento, se han realizado diferentes experimentos numéricos con el modelo RAMS, con el fin de evaluar la influencia que diferentes parámetros físicos y fisiográficos tienen en los resultados de simulación. Se ha analizado, por un lado, el papel de la orografía en este tipo de eventos y, por otro, el que representan las parametrizaciones convectivas actualmente implementadas en el modelo RAMS (Kuo y Kain-Fritsch) al ser activadas o desactivadas en diferentes dominios de simulación. De los diferentes experimentos llevados a cabo se desprende que el modelo RAMS es una herramienta adecuada que permite reproducir las características principales de las lluvias torrenciales en la zona de estudio. Además, se ha demostrado que eliminar la orografía en la zona de precipitación resulta en una disminución de la intensidad del ascenso orográfico en las primeras cadenas montañosas cercanas a la costa. Como consecuencia, la precipitación observada se ve disminuida en relación a la simulación que tiene en cuenta la orografía, y el grueso de precipitación se desplaza hacia el interior. Finalmente, se ha podido constatar cómo activar Kuo y Kain-Fritsch a diferente resolución horizontal produce resultados divergentes en las distintas variables y procesos físicos analizados. Comparando ambos esquemas de cúmulos, Kuo obtiene, en general, resultados superiores a Kain-Fritsch. Igualmente, el efecto de activar la parametrización de Kuo en dominios de mayor resolución mejora los resultados de previsión de la precipitación total acumulada. En cambio, activar la parametrización de Kain-Fritsch en estos dominios disminuye la precipitación simulada.The first aim of this Thesis is related to the development and implementation of different warning and alert systems within the Valencia Region: a meteorological real-time forecasting system based on the Regional Atmospheric Modeling System (RAMS) and a UV Index (UVI) forecasting system based on the Santa Barbara Disort Model Atmospheric Radiative Transfer (SBDART). Furthermore, we propose a methodology that provides a computational environment suitable for the management and coordination of the different processes involved in both systems. The main improvement in the UVI forecast is related to using the total ozone column data obtained from the model Global Forecast System (GFS), rather than the data derived from the Ozone Monitoring Instrument (OMI) used in the original system. The validation of the results obtained by the UVI forecast system for the year 2008 shows a high degree of agreement between the modeling and the observations, taking into account a difference of one unit in the UV Index. Besides, the use of total ozone column from the GFS shows a slight improvement over the forecast obtained with the original system. The second aim of the current Thesis is related to the modeling of climate risks typical within the Valencia Region. In this sense, we have selected a recent episode of heavy rain, which took place on the 11th and 12th October 2007. Using this event, numerical experiments have been performed using the RAMS model in order to evaluate the influence of different physical parameters in the simulation results. On the one hand, we have analyzed the role of the orography in this sort of events. On the other hand, we have dealt with the effect of using the different convective parameterizations currently implemented in the RAMS model (Kuo and Kain-Fritsch) in the forecast results. Sensitivity tests have been run with and without these parameterizations activated in a series of combinations of the different grids. From the various experiments carried out it is shown that RAMS is a suitable tool to capture and represent the main characteristics of torrential rains in the area of study. In addition, removing the orography for the inner grid results in a decrease in intensity in the first mountain ranges close to the coast. Consequently, the observed precipitation is diminished in relation to the simulation that takes into account this parameter, and the bulk of precipitation moves inland. Finally, it has also been shown that activating Kuo and Kain-Fritsch at different horizontal resolution domains produces different results in the different variables and physical processes analyzed. Comparing both convective schemes, Kuo produces in general better results than Kain-Fritsch. Similarly, the effect of activating the Kuo parameterization on higher horizontal resolution domains improves the total precipitation results. Instead, activating the Kain-Fritsch parameterization for these domains decreases the simulated precipitation

Improving RAMS and WRF mesoscale forecasts over two distinct vegetation covers using an apprpiate thermal roughness length parameterization

Land Surface Models (LSM) have shown some difficulties to properly simulate day-time 2-m air and surface skin temperatures. This kind of models are coupled to atmospheric models in mesoscale modelling, such as the Regional Atmospheric Modeling System (RAMS) and the Weather Research and Forecasting (WRF) Model. This model coupling is used within Numerical Weather Prediction Systems (NWP) in order to forecast key physical processes for agricultural meteorology and forestry as well as in ecological modelling. The current study first evaluates the surface energy fluxes and temperatures simulated by these two state-of-the-art NWP models over two distinct vegetated covers, one corresponding to a poor and sparsely vegetated area and the other one corresponding to the tall and well-vegetated area of a forest. On the other hand, the importance of parameterizing the thermal roughness length within the LSM coupled to the corresponding atmospheric model is also evaluated. The LEAF-3 LSM is used within the RAMS modelling environment while the Noah-MP LSM is applied within WRF. Results indicate that the original version of the models underestimates the temperature during the day, more remarkably in the forested area, whereas modifications in the thermal roughness length successfully simulates the temperature and sensible heat flux forecasts over this area. This study highlights the key role of the surface exchange processes when coupling land and atmosphere models. In this regard, incorporating an extra resistance in the surface-layer parameterization through the thermal roughness length is essential to simulate well both temperatures and sensible heat fluxes, which becomes more relevant over tall and well-vegetated areas, such as a forest. This extra resistance for heat exchange prevents effective molecular diffusion in the layer between the momentum roughness length and the thermal roughness length. Additionally, an appropriate description of the canopy height permits to apply an improved surface-layer formulation over different land and vegetation covers

RAMS-forecasts comparison of typical summer atmospheric conditions over the Western Mediterranean coast

The Regional Atmospheric Modeling System (RAMS) has been used in order to perform a high-resolution numerical simulation of two meteorological events related to the most common atmospheric environments during the summer over the Western Mediterranean coast: mesoscale circulations and western synoptic advections. In this regard, we take advantage of the operational RAMS configuration running within the real-time forecasting system environment already implemented over this Mediterranean area, precisely in the Valencia Region and nearby areas. The attention of this paper is especially focused on identifying the main features of both events and the ability of the model in resolving the associated characteristics as well as in performing a comprehensive evaluation of the model by means of diverse meteorological observations available within the selected periods over the area of study. Additionally, as this paper is centred in RAMS-based forecasts, two simulations are operated applying the most two recent versions of the RAMS model implemented in the above-mentioned system: RAMS 4.4 and RAMS 6.0. Therefore, a comparison among both versions of the model has been performed as well. Finally, it is our intention to contrast the RAMS forecasts for two completely different atmospheric conditions common with the area of study in the summer. A main difference between the simulation of both meteorological situations has been found in the humidity. In this sense, whilst the model underestimates this magnitude considering the mesoscale event, especially at night time, the model reproduces the daily humidity properly under the western synoptic advection

Comparative assessment of RAMS and WRF short-term forecasts over Eastern Iberian Peninsula using various in-situ observations, remote sensing products and uncoupled land surface model datasets

The Regional Atmospheric Modeling System (RAMS) and the Weather Research and Forecasting (WRF) mesoscale models are being used for weather and air quality studies as well as forecasting tools in Numerical Weather Prediction (NWP) systems. In the current study, we perform a comparative assessment of these models under distinct typical atmospheric conditions, classified according to the dominant wind flow and cloudiness, over Eastern Iberian Peninsula. This study is focused on the model representation of key physical processes in terms of meteorology and surface variables during a 7-days period in summer 2011. The hourly outputs produced by these two models are compared not only with observed standard surface variables, measured at different permanent weather stations located over the region of study, but also with different surface remote sensing products and uncoupled Land Surface Models (LSM) datasets. Confronting RAMS and WRF, the current study highlights relevant differences over areas near the coast when mesoscale circulations or Eastern synoptic advections are developed over the region of study. A higher moisture content is observed under these atmospheric conditions, due to the moisture transport by the sea breeze inland. In this regard, it has been found that the Eastern wind field simulated by WRF reaches inland areas and comprises a larger sea breeze extension than RAMS. This sea breeze development impacts meteorology and surface variables in locations not too close to the coast, but still affected by land-sea winds. Additionally, WRF remains more windy and moister than RAMS at night-time, while alike results are found under Western synoptic advections. The results obtained in the current paper show differences under distinct dominant atmospheric conditions, which outline further research in this field in order to achieve more general conclusions

Improved meteorology and surface fluxes in mesoscale modelling using adjusted initial vertical soil moisture profiles

The Regional Atmospheric Modeling System (RAMS) is being used for different and diverse purposes, ranging from atmospheric and dispersion of pollutants forecasting to agricultural meteorology and ecological modelling as well as for hydrological purposes, among others. The current paper presents a comprehensive assessment of the RAMS forecasts, comparing the results not only with observed standard surface meteorological variables, measured at FLUXNET stations and other portable and permanent weather stations located over the region of study, but also with non-standard observed variables, such as the surface energy fluxes, with the aim of evaluating the surface energy budget and its relation with a proper representation of standard observations and key physical processes for a wide range of applications. In this regard, RAMS is assessed against in-situ surface observations during a selected period within July 2011 over Eastern Spain. In addition, the simulation results are also compared with different surface remote sensing data derived from the Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) (MSG-SEVIRI) as well as the uncoupled Land Surface Models (LSM) Global Land Data Assimilation System (GLDAS). Both datasets complement the available in-situ observations and are used in the current study as the reference or ground truth when no observations are available on a selected location. Several sensitivity tests have been performed involving the initial soil moisture content, by adjusting this parameter in the vertical soil profile ranging from the most superficial soil layers to those located deeper underground. A refined adjustment of this parameter in the initialization of the model has shown to better represent the observed surface energy fluxes. The results obtained also show an improvement in the model forecasts found in previous studies in relation to standard observations, such as the air temperature and the moisture fields. Therefore, the application of a drier or wetter soil in distinct soil layers within the whole vertical soil profile has been found to be crucial in order to produce a better agreement between the simulation and the observations, thus reiterating the determining role of the initial soil moisture field in mesoscale modelling, but in this case considering the variation of this parameter vertically

The new methods for rapid exposure and seismic vulnerability assessment. How do they adapt to different scenarios?

We present a procedure for exposure and vulnerability evaluation that integrates LiDAR, orthophotos, and other ancillary datasets. It comprises three phases: (1) city stratification into homogeneous regions; (2) exposure database compilation; and (3) vulnerability allocation using predictive modelling. We have conducted two applications in Lorca (Spain) and Port-au-Price (Haiti) and here we compare them. Each phase of the method is subject to variations due mainly to data availability; however, it does not affect the final accuracy that remains high in both scenarios (over 80%). It is a flexible procedure that is able to adapt to the particular features of two different cities