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Rodriguez R.,Polytechnic University of Catalonia | Navarro X.,Polytechnic University of Catalonia | Casas M.C.,Polytechnic University of Catalonia | Ribalaygua J.,Fundacion para la Investigacion del Clima | And 3 more authors.
International Journal of Climatology | Year: 2014

The evaluation of the possible climate change influence on extreme precipitation is very interesting in the Mediterranean area due to the usual and characteristic high intensities of its rainfall pattern. This analysis is also very important in urban zones, especially those densely populated with complex sewer systems, generally vulnerable to torrential rainfall. In this work, a total of 114 simulated daily rainfall series, 84 for the period 2000-2099 and 30 for the control period 1951-1999, have been analysed. These series were obtained for six thermo-pluviometric stations located in the metropolitan area of Barcelona using the information provided by five general circulation models under four future climate scenarios of greenhouse gas emissions and applying statistical downscaling methods. The potential changes in the intensity-duration-frequency relationships due to climate change have been investigated. For the last third of the 21st century, under A1B, A2 and B2 climate scenarios, an increase of at least 4% has been found on the expected daily rainfall with return period longer than 20years. Using a temporal downscaling based on scaling properties of rainfall, future hourly extreme rainfall has been estimated. For almost all the scenarios and periods considered, the increase on the expected hourly rainfall has resulted slightly higher than the corresponding daily rainfall. The greatest differences between the future hourly and daily rainfall estimated have been found in the second third of the century under scenarios A1B (8%) and A2 (9%). © 2013 Royal Meteorological Society.

Moncho R.,Fundacion para la Investigacion del Clima | Moncho R.,University of Valencia | Caselles V.,University of Valencia | Chust G.,Tecnalia
Climate Research | Year: 2012

In climatology, there is difficulty in describing the probability distribution of rainfall because there are many days without precipitation, which usually causes the most likely daily rainfall to be zero. None of the widely used models is able to describe the overall variation of daily precipitation. This article proposes an alternative model for the probability of precipitation. The model, based on 4 parameters, has been applied to daily rainfall throughout all months of the year and for 108 stations in Spain. This alternative model provides better results than the commonly used probability models (Generalized Extreme Value, Pareto and Generalized Pareto Distribution, Gamma, Gumbel, Weibull, Exponential and Log-normal). Our model had a mean absolute error of <10% for most of the stations analyzed. Thus, this alternative model could be used to correct the probability distributions of daily precipitation obtained from weather forecasting and climate models. © Inter-Research 2012.

Ribalaygua J.,Fundacion para la Investigacion del Clima | Torres L.,Fundacion para la Investigacion del Clima | Portoles J.,Fundacion para la Investigacion del Clima | Monjo R.,Fundacion para la Investigacion del Clima | And 2 more authors.
Theoretical and Applied Climatology | Year: 2013

This study describes a two-step analogue statistical downscaling method for daily temperature and precipitation. The first step is an analogue approach: the "n" days most similar to the day to be downscaled are selected. In the second step, a multiple regression analysis using the "n" most analogous days is performed for temperature, whereas for precipitation, the probability distribution of the "n" analogous days is used to define the amount of precipitation. Verification of this method has been carried out for the Spanish Iberian Peninsula and the Balearic Islands. Results show good performance for temperature (BIAS close to 0.1 °C and mean absolute errors around 1.9 °C) and an acceptable skill for precipitation (reasonably low BIAS except in autumn with a mean of -18 %, mean absolute error lower than for a reference simulation, i.e. persistence and a well-simulated probability distribution according to two non-parametric tests of similarity). © 2013 Springer-Verlag Wien.

Ribalaygua J.,Fundacion para la Investigacion del Clima | Pino R.M.,San Jorge University | Portoles J.,Fundacion para la Investigacion del Clima | Roldan E.,San Jorge University | And 3 more authors.
Science of the Total Environment | Year: 2013

By applying a two-step statistical downscaling technique to four climate models under different future emission scenarios, we produced future projections of the daily precipitation and the maximum and minimum temperatures over the Spanish region of Aragón. The reliability of the downscaling technique was assessed by a verification process involving the comparison of the downscaled reanalysis data with the observed data - the results were very good for the temperature and acceptable for the precipitation. To determine the ability of the climate models to simulate the real climate, their simulations of the past (the 20C3M output) were downscaled and then compared with the observed climate. The results are quite robust for temperature and less conclusive for the precipitation. The downscaled future projections exhibit a significant increase during the entire 21st century of the maximum and minimum temperatures for all the considered IPCC future emission scenarios (A2, A1B, B1), both for mid-century (increases relative to the 1971-2000 averages between 1.5°C and 2.5°C, depending on the scenario) and for the end of the century (for the maximum temperature of approximately 3.75°C, 3.3°C, and 2.1°C for A2, A1B, and B1 scenarios respectively, and for the minimum temperature of 3.1°C, 2.75°C, and 1.75°C). The precipitation does not follow such a clear tendency (and exhibits greater uncertainties), but all the scenarios suggest a moderate decrease in rainfall for the mid-century (2-4%) and for the end of the century (4.5-5.5%). Due to the clear spatial differences in climate characteristics, we divided the studied area into five sub-regions to analyse the different changes on these areas; we determined that the high mountains (Pyrenees, Mediterranean-Oceanic transitional climate) and the lands of the Ebro River Basin (Continental sub-Mediterranean climate) will probably be the most affected. © 2013 Elsevier B.V.

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