http://hdl.handle.net/2117/3859 Sun, 19 May 2013 14:03:51 GMT 2013-05-19T14:03:51Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19180 Title: Blending of radar and gauge rainfall measurements: a preliminary analysis of the impact of radar errors Authors: Sempere Torres, Daniel; Berenguer Ferrer, Marc; Velasco Forero, Carles Abstract: Several methodologies have been proposed to combine radar and raingauge measurements with the aim of generating improved quantitative precipitation estimates (QPEs). These methods are based on interpolating point raingauge measurements (implicitly assumed to be “the truth”) and benefiting from the structure of the rainfall field as depicted by the radar. The use of a non-parametric approach based on radar measurements has been recently demonstrated, showing the benefits in the interpolation of raingauge measurements under the hypotheses of the Kriging approach. Several experiments have been carried out over a large number of cases and a variety of regions, Kriging with an external drift (i.e. the radar description of the rainfall field) being the approach showing more robust and (overall) better performance. Here, the impact of the discrepancies between two almost-collocated radars on the blended QPE fields was investigated. Mon, 13 May 2013 13:09:06 GMT http://hdl.handle.net/2117/19180 2013-05-13T13:09:06Z Sempere Torres, Daniel; Berenguer Ferrer, Marc; Velasco Forero, Carles no QPE, radar-raingauge blending, spatial variability of rainfall, radar errors, radar calibration Several methodologies have been proposed to combine radar and raingauge measurements with the aim of generating improved quantitative precipitation estimates (QPEs). These methods are based on interpolating point raingauge measurements (implicitly assumed to be “the truth”) and benefiting from the structure of the rainfall field as depicted by the radar. The use of a non-parametric approach based on radar measurements has been recently demonstrated, showing the benefits in the interpolation of raingauge measurements under the hypotheses of the Kriging approach. Several experiments have been carried out over a large number of cases and a variety of regions, Kriging with an external drift (i.e. the radar description of the rainfall field) being the approach showing more robust and (overall) better performance. Here, the impact of the discrepancies between two almost-collocated radars on the blended QPE fields was investigated. http://hdl.handle.net/2117/18644 Title: Ensemble radar precipitation estimation for nowcasting and hydrology in the Alps Authors: Germann, Urs; Hering, Alessandro; Berenguer Ferrer, Marc; Sempere Torres, Daniel; Salvadè, Georges Abstract: This paper explores the novel idea of generating ensables of radar precipitation estimates. Fri, 05 Apr 2013 11:35:36 GMT http://hdl.handle.net/2117/18644 2013-04-05T11:35:36Z Germann, Urs; Hering, Alessandro; Berenguer Ferrer, Marc; Sempere Torres, Daniel; Salvadè, Georges no This paper explores the novel idea of generating ensables of radar precipitation estimates. http://hdl.handle.net/2117/16962 Title: Predictability assessment of nowcasts in high-impact heavy precipitation events Authors: Bech, Joan; Berenguer Ferrer, Marc Mon, 19 Nov 2012 18:55:18 GMT http://hdl.handle.net/2117/16962 2012-11-19T18:55:18Z Bech, Joan; Berenguer Ferrer, Marc no http://hdl.handle.net/2117/15630 Title: Flow structure and resistance in flexible vegetated channels Authors: Velasco Montes, David; Bateman Pinzón, Allen; Redondo Apraiz, José Manuel Abstract: The present paper helps to understand the behaviour of the flow through plants, as a first approximation to the environmental interactions happening in natural rivers. Wed, 21 Mar 2012 10:34:48 GMT http://hdl.handle.net/2117/15630 2012-03-21T10:34:48Z Velasco Montes, David; Bateman Pinzón, Allen; Redondo Apraiz, José Manuel no The present paper helps to understand the behaviour of the flow through plants, as a first approximation to the environmental interactions happening in natural rivers. http://hdl.handle.net/2117/13456 Title: A variational approach to retrieve 3D radar reflectivity composites Authors: Roca Sancho, Jordi; Berenguer Ferrer, Marc; Sempere Torres, Daniel Abstract: This study proposes an alternative methodology to obtain high-resolution radar reflectivity composites based on a variational approach considering different error sources in an explicit manner. The methodology retrieves the 3-dimensional precipitation field most compatible with the observations from the different radars of the network. With this aim, the methodology uses a model that simulates the radar sampling of the atmosphere. The model settings are different for each radar and include features such as the radar location, hardware parameters (beam width, pulse length…) and the scan strategy. The methodology follows the concept of an inverse method based on the minimization of a cost function that penalizes discrepancies between the simulated and actual observations for each radar. The simulation model is able to reproduce the effect of beam broadening with the distance and attenuation by intense precipitation. The methodology has been applied on two radars close to Barcelona (Spain). Fri, 07 Oct 2011 12:07:28 GMT http://hdl.handle.net/2117/13456 2011-10-07T12:07:28Z Roca Sancho, Jordi; Berenguer Ferrer, Marc; Sempere Torres, Daniel no This study proposes an alternative methodology to obtain high-resolution radar reflectivity composites based on a variational approach considering different error sources in an explicit manner. The methodology retrieves the 3-dimensional precipitation field most compatible with the observations from the different radars of the network. With this aim, the methodology uses a model that simulates the radar sampling of the atmosphere. The model settings are different for each radar and include features such as the radar location, hardware parameters (beam width, pulse length…) and the scan strategy. The methodology follows the concept of an inverse method based on the minimization of a cost function that penalizes discrepancies between the simulated and actual observations for each radar. The simulation model is able to reproduce the effect of beam broadening with the distance and attenuation by intense precipitation. The methodology has been applied on two radars close to Barcelona (Spain). http://hdl.handle.net/2117/13455 Title: A radar-based flash flood forecasting for the Llobregat river basin in the Catalonia region (Spain) Authors: Quintero Duque, Felipe; Versini, Pierre Antonie; Baltas, Evangelos; Berenguer Ferrer, Marc; Sempere Torres, Daniel Abstract: In this research paper, a flash flood modeling system implemented in a Mediterranean river basin is presented. Radar precipitation estimation along with hydrological modeling techniques are implemented within the system for simulating the runoff generation and routing processes occurring in the catchment. However, there exists an uncertainty related with the estimation of radar precipitation (Zawadzki, 1984) and from model calibration (Beven, 2006). Such uncertainty is propagated to the resulting discharge simulations. The aim of this research paper is to propose a methodology to analyze the propagation of uncertainty occurring at the different processes of the modeling system. For this purpose, a Monte Carlo simulation approach is used to consider the uncertainty arising from rainfall and model parameter estimation. Fri, 07 Oct 2011 11:52:20 GMT http://hdl.handle.net/2117/13455 2011-10-07T11:52:20Z Quintero Duque, Felipe; Versini, Pierre Antonie; Baltas, Evangelos; Berenguer Ferrer, Marc; Sempere Torres, Daniel no In this research paper, a flash flood modeling system implemented in a Mediterranean river basin is presented. Radar precipitation estimation along with hydrological modeling techniques are implemented within the system for simulating the runoff generation and routing processes occurring in the catchment. However, there exists an uncertainty related with the estimation of radar precipitation (Zawadzki, 1984) and from model calibration (Beven, 2006). Such uncertainty is propagated to the resulting discharge simulations. The aim of this research paper is to propose a methodology to analyze the propagation of uncertainty occurring at the different processes of the modeling system. For this purpose, a Monte Carlo simulation approach is used to consider the uncertainty arising from rainfall and model parameter estimation. http://hdl.handle.net/2117/11046 Title: A methodology for attenuation correction based on the minimization of a cost function Authors: Berenguer Ferrer, Marc; Lee, G.; Sempere Torres, Daniel; Zawadzki, Isztar Fri, 14 Jan 2011 18:32:05 GMT http://hdl.handle.net/2117/11046 2011-01-14T18:32:05Z Berenguer Ferrer, Marc; Lee, G.; Sempere Torres, Daniel; Zawadzki, Isztar no http://hdl.handle.net/2117/11045 Title: Hydrological evaluation of a nowcasting technique applied to flood forecasting Authors: Berenguer Ferrer, Marc; Dàvila, J.; Corral Alexandri, Carles; Sempere Torres, Daniel; Seed, Alan Fri, 14 Jan 2011 18:26:44 GMT http://hdl.handle.net/2117/11045 2011-01-14T18:26:44Z Berenguer Ferrer, Marc; Dàvila, J.; Corral Alexandri, Carles; Sempere Torres, Daniel; Seed, Alan no http://hdl.handle.net/2117/11044 Title: Improving radar rainfall measurement stability using mountain returns in real time. Authors: Sempere Torres, Daniel; Sánchez-Diezma Guijarro, Rafael; Berenguer Ferrer, Marc; Pascual Berghaenel, Ramon; Zawadzki, Isztar Fri, 14 Jan 2011 18:20:22 GMT http://hdl.handle.net/2117/11044 2011-01-14T18:20:22Z Sempere Torres, Daniel; Sánchez-Diezma Guijarro, Rafael; Berenguer Ferrer, Marc; Pascual Berghaenel, Ramon; Zawadzki, Isztar no http://hdl.handle.net/2117/11043 Title: Validation of a nowcasting technique from a hydrological perspective Authors: Berenguer Ferrer, Marc; Corral Alexandri, Carles; Sempere Torres, Daniel; Seed, A W Abstract: Nowcasting precipitation is a key point to anticipate risks in flood warning systems. In this environment, weather radars are very useful because of the high resolution of their measurements both in time and space. The aim of this study is to assess the performance of a recently proposed nowcasting technique (SPROG) from a hydrological point of view. This technique is based on the advection of radar precipitation fields and its main point is that the forecasted fields get smoothed as the forecasting time increases, to filter out the smallest scales of the field when they become unpredictable. The evaluation of the forecasted precipitation fields is done in two different ways: a) comparing them against the actually measured precipitation fields and b) according to the concept of “hydrological validation”, comparing the hydrographs calculated by a distributed rainfall-runoff model simulating operational conditions (using the forecasted precipitation fields) against the hydrographs calculated by the model with the entire series of radar measurements. This part of the study has been carried out in the framework of the Besos basin flood forecasting system. Fri, 14 Jan 2011 18:11:06 GMT http://hdl.handle.net/2117/11043 2011-01-14T18:11:06Z Berenguer Ferrer, Marc; Corral Alexandri, Carles; Sempere Torres, Daniel; Seed, A W no Nowcasting precipitation is a key point to anticipate risks in flood warning systems. In this environment, weather radars are very useful because of the high resolution of their measurements both in time and space. The aim of this study is to assess the performance of a recently proposed nowcasting technique (SPROG) from a hydrological point of view. This technique is based on the advection of radar precipitation fields and its main point is that the forecasted fields get smoothed as the forecasting time increases, to filter out the smallest scales of the field when they become unpredictable. The evaluation of the forecasted precipitation fields is done in two different ways: a) comparing them against the actually measured precipitation fields and b) according to the concept of “hydrological validation”, comparing the hydrographs calculated by a distributed rainfall-runoff model simulating operational conditions (using the forecasted precipitation fields) against the hydrographs calculated by the model with the entire series of radar measurements. This part of the study has been carried out in the framework of the Besos basin flood forecasting system. http://hdl.handle.net/2117/11042 Title: Identification of clutter echoes using a fuzzy logic technique Authors: Berenguer Ferrer, Marc; Sempere Torres, Daniel; Sánchez-Diezma Guijarro, Rafael; Pascual Berghaenel, Ramon Fri, 14 Jan 2011 16:23:38 GMT http://hdl.handle.net/2117/11042 2011-01-14T16:23:38Z Berenguer Ferrer, Marc; Sempere Torres, Daniel; Sánchez-Diezma Guijarro, Rafael; Pascual Berghaenel, Ramon no http://hdl.handle.net/2117/11041 Title: Modeling the uncertainty associated to radar-based nowcasting techniques. Impact in flow simulation Authors: Berenguer Ferrer, Marc; Sempere Torres, Daniel; Sánchez-Diezma Guijarro, Rafael; Pegram, Geoffrey; Zawadzki, Isztar; Seed, Alan Fri, 14 Jan 2011 16:07:15 GMT http://hdl.handle.net/2117/11041 2011-01-14T16:07:15Z Berenguer Ferrer, Marc; Sempere Torres, Daniel; Sánchez-Diezma Guijarro, Rafael; Pegram, Geoffrey; Zawadzki, Isztar; Seed, Alan no http://hdl.handle.net/2117/10992 Title: Bias-corrected nonparametric correlograms for geostatistical radar-raingauge combination Authors: Schiemann, Reinhard; Erdin, Rebekka; Willi, Marco; Frei, Christoph; Berenguer Ferrer, Marc; Sempere Torres, Daniel Abstract: Geostatistical methods have been widely used for quantitative precipitation estimation (QPE) based on the combination of radar and raingauge observations. They are flexible and accurate and allow for radar-raingauge combination in real-time. Even within the area of geostatistical methods, however, a wide range of choices have to be made when planning for a particular application. These choices regard, for example, the actual combination method (e.g., kriging with external drift, cokriging), the kriging neighbourhood (global vs. local), the technique used to estimate the parameters of the geostatical model (e.g., least-squares, maximum-likelihood estimation), and the transformation of the precipitation variable. In addition to these issues, there are a number of options for modeling spatial dependencies in the precipitation data. Correlograms (variograms) for kriging are customarily one-dimensional, but two- or higher-dimensional correlation maps are also used and are one way of taking spatial anisotropy into account. Furthermore, correlograms can be parametric or nonparametric, they can be obtained from the radar or the raingauge data, and they can be estimated flexibly on a case-by-case basis or with data from a longer period of time. Recently, nonparametric correlograms based on spatially complete radar rainfall fields have been used in combining radar and raingauge data [1]. Here, we compare the estimation of nonparametric correlograms with the estimation of parametric semivariogram models conventionally used in geostatistical applications. We identify and explain a bias of the nonparametric correlograms towards too low ranges, and suggest a correction for this bias. Wed, 12 Jan 2011 18:33:19 GMT http://hdl.handle.net/2117/10992 2011-01-12T18:33:19Z Schiemann, Reinhard; Erdin, Rebekka; Willi, Marco; Frei, Christoph; Berenguer Ferrer, Marc; Sempere Torres, Daniel no Geostatistical methods have been widely used for quantitative precipitation estimation (QPE) based on the combination of radar and raingauge observations. They are flexible and accurate and allow for radar-raingauge combination in real-time. Even within the area of geostatistical methods, however, a wide range of choices have to be made when planning for a particular application. These choices regard, for example, the actual combination method (e.g., kriging with external drift, cokriging), the kriging neighbourhood (global vs. local), the technique used to estimate the parameters of the geostatical model (e.g., least-squares, maximum-likelihood estimation), and the transformation of the precipitation variable. In addition to these issues, there are a number of options for modeling spatial dependencies in the precipitation data. Correlograms (variograms) for kriging are customarily one-dimensional, but two- or higher-dimensional correlation maps are also used and are one way of taking spatial anisotropy into account. Furthermore, correlograms can be parametric or nonparametric, they can be obtained from the radar or the raingauge data, and they can be estimated flexibly on a case-by-case basis or with data from a longer period of time. Recently, nonparametric correlograms based on spatially complete radar rainfall fields have been used in combining radar and raingauge data [1]. Here, we compare the estimation of nonparametric correlograms with the estimation of parametric semivariogram models conventionally used in geostatistical applications. We identify and explain a bias of the nonparametric correlograms towards too low ranges, and suggest a correction for this bias. http://hdl.handle.net/2117/8844 Title: Analysis of the radar distance error structure through a simulation approach Authors: Llort Pavon, Xavier; Berenguer Ferrer, Marc; Sánchez-Diezma Guijarro, Rafael; Sempere Torres, Daniel Description: Radar precipitation estimates are affected by inherent errors of different sources. Although sophisticated algorithms have been developed to correct several errors, final precipitation products are not free of errors. The study of the remaining errors affecting radar rainfall estimates is becoming as important as the retrieval estimates themselves. Tue, 14 Sep 2010 09:15:41 GMT http://hdl.handle.net/2117/8844 2010-09-14T09:15:41Z Llort Pavon, Xavier; Berenguer Ferrer, Marc; Sánchez-Diezma Guijarro, Rafael; Sempere Torres, Daniel no http://hdl.handle.net/2117/7189 Title: Improvements on flow forecasting using precipitation nowcasting based in radar advection techniques: assessment of predictability and uncertainty propagation Authors: Sempere Torres, Daniel; Berenguer Ferrer, Marc; Corral Alexandri, Carles; Sánchez-Diezma Guijarro, Rafael Wed, 12 May 2010 15:31:04 GMT http://hdl.handle.net/2117/7189 2010-05-12T15:31:04Z Sempere Torres, Daniel; Berenguer Ferrer, Marc; Corral Alexandri, Carles; Sánchez-Diezma Guijarro, Rafael no