Non-stationary future return levels for extreme rainfall over Extremadura (southwestern Iberian Peninsula) |
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| Authors: | Francisco Javier Acero Sylvie Parey Thi Thu Huong Hoang Didier Dacunha-Castelle José Agustín García María Cruz Gallego |
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| Institution: | 1. Departamento de Física, Instituto del Agua, Cambio Climático y Sostenibilidad, Universidad de Extremadura, Badajoz, Spain;2. EDF/R&3. D, Chatou, France;4. Laboratoire de Mathématiques, Université Paris 11, Orsay, France |
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| Abstract: | Based on a previous study for temperature, a new method for the calculation of non-stationary return levels for extreme rainfall is described and applied to Extremadura, a region of southwestern Spain, using the peaks-over-threshold approach. Both all-days and rainy-days-only datasets were considered and the 20-year return levels expected in 2020 were estimated taking different trends into account: first, for all days, considering a time-dependent threshold and the trend in the scale parameter of the generalized Pareto distribution; and second, for rainy days only, considering how the mean, variance, and number of rainy days evolve. Generally, the changes in mean, variance and number of rainy days can explain the observed trends in extremes, and their extrapolation gives more robust estimations. The results point to a decrease of future return levels in 2020 for spring and winter, but an increase for autumn. |
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| Keywords: | extreme value theory return levels extreme rainfall peaks over threshold |
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