HYDROMETEOROLOGY

Author: RIBO RIBAS BARTOLOMÉ.
Year: 2003.
University: BARCELONA [www.ub.es].
Place of defense: FÍSICA.
Place of preparation: FACULTAD DE FÍSICA. UNIVERSIDAD DE BARCELONA.

Summary: The main aim of the thesis the anilizar from radar meteorologíco, along with other systems (pulviómetros, radiosonde stations or automatic models), the structures that produce rainfall episodes of heavy rains in Cataluya, especially Systems Convectivos Mesoescalares given their partnership for a large number of eventos.Con this end have developed all the necessary tools for data processing radar and precipitation in surperficie and thermodynamics and mesoescalar.Por other hand have been identified and selected cases of heavy rains that afectarón the Inland Basins de Catalunya between 1996 and 2000, having gained 43 episodio.Sobre them have been implemented systematically tools developed within the argument, both from a climatic point of view (analysis of all events and their characteristics) weather (case studies of particular interest). The development of tools radar contemplates the realization of an algorithm for identifying own structures 2D and 3D, as adapted and improved some models propuestso in bibliografía.Asimismo provides for the identification and precipitation convenctiva surfaced from the parameter B for a better definition of the threshold to considerar.Mediante the implementation of such algorithms has been done climatology of the structures of precipitation (including part convecting and stratified), as well as the convective structures in 3D and 3D, contemplating the life cycle and indicators such as the density of VIL, VIL, echo Top, etc.Cabe stress here also proposed classification Systems Convectivos Mesoescalares.Además has done analysis for surface rainfall in all situations, identifying the type of precipitation, the affected area, or distrinbución mensual.Taermdinámicamente, have sought some significant aspects of different parameters (CAPE, LI, MAP), according to the type of episode, and for different seasons Mediterranean, and its influence on the structure identified by rainfall weather radar. In a final phase, which also included information from the numerical models, have experimented with nowcasting for predicting precipitation to 3 hours views. The case analysis has focused on the events of June 2000, with severe flooding in Montserrat and in January and October 1996.En these cases have been dealt with in detail the various weather factors involved and their synergy, particularly in the movement and spread of the convective cells within the system itself, and its consequent impact on the rainfall recorded at the surface, the type of structure and the identification and movement of the línez convergence.

Author: BERENGUER FERRER MARC.
Year: 2005.
University: POLITÉCNICA DE CATALUÑA [www.upc.edu].
Place of defense: edifici c-1, aula 002- campus nord.
Place of preparation: ETSECCPB, EDIFICI C2 Campus NORD.

Summary: Floods are the natural hazard in Europe (especially in our area, due to its particular geo-morphological and climatic characteristics). Even though protection against floods has traditionally been faced with structural solutions (construction of big infrastructures), nowadays, these infrastructures have been complemented with hydrological warning systems, which allow anticipating risks and issue warnings with the purpose of minimizing losses. In this framework, weather radars are tools that provide valuable information related to the 3D structure of the precipitation field with a resolution (both spatial and temporal) very appropriate to fulfill the requirements of hydrological warning systems (especially when this information is coupled with distributed rainfall-runoff models). However, radar measurements are affected by a series of error sources, which limit its quantitative applications and it is necessary to correct them. This thesis is devoted to the study of quantitative uses of radar information, and especially its hydrological applications. The existence of radar echoes due to non-meteorological targets (such as the orography, big buildings,...) is one of the error sources that contaminate radar information. Moreover, this phenomenon is especially relevant in particular atmospheric conditions: in these conditions, the emitted radiation is anomaly propagated. In extreme cases, this may result in the appearance of non-meteorological echoes in the areas where the beam reaches the surface (even over the sea). In the framework of this thesis, an algorithm for identifying these echoes has been proposed and implemented over a large data set simulating operational conditions. On the other hand, an algorithm for mitigating the effects of signal attenuation caused by precipitation has also been developed and implemented. This is one of the phenomena that could seriously limit the quantitative uses of operational radars in Europe (due to the chosen wavelength). Finally, we have also studied the interest of coupling a short-term rainfall forecasting technique based on radar measurements with a distributed hydrological model in the Besòs basin. Results show significant improvements when this kind of techniques is used, which allows extending the anticipation with which hydrographs can be forecasted. Besides of that, we have also analyzed the factors related to the forecasting techniques that affect the quality of simulated flows.