DATE2016-05-23 10:35:15
AUTHORSKatrin M. Nissen (1), Uwe Ulbrich (1)
  1. Freie Universität Berlin Berlin (Germany)
ABSTRACTFrequencies of heavy precipitation events potentially threatening local infrastructures in the Mediterranean region are inidentified from a multi-model ensemble of regional climate model simulations conducted within the EURO-CORDEX framework. The simulations exhibit a horizontal resolution of approximately 12.5 km. Climate change impacts are computed comparing results from present day and and scenario (RCP 8.5 and RCP 4.5) greenhouse gas concentrations. We assume that precipitation in excess of the local present-day 10-year return value is potentially damaging to infrastructure. This assumption is based on legislation for the design of drainage systems in Central Europe and from European-wide rules for railroad systems. An event based detection algorithm for extreme precipitation identifies events exceeding the 10-year return value. It determines extent, location, duration and severity of the extreme precipitation events. We distinguish between sub-daily events, which exceed the 3-hourly 10-year return level (events with high precipitation intensities) and multi-day events, which exceed the 24, 48 and/or 72 hour 10-year return levels (events with high precipitation amounts). 13 simulations were analysed with respect to multi-day events. 3-hourly data for the analysis of sub-daily events was available for 7 simulations. Examined are changes in event frequency, event duration and size. In contrast to most other European areas, the simulations show a minimum in extreme precipitation during summer in the Mediterranean Region, while the maximum is found during autumn. In the western Mediterranean region the number of multi-day events is forecast to further decrease during summer. In the other Mediterranean areas and seasons the multi-model ensemble predicts a slight increase in the number of multi-day events, which is much weaker than in other European areas. For sub-daily events, however, all Mediterranean regions show a decrease in the number of events during summer and a considerable increase during the colder seasons. The median in the events’ spatial extension constant for multi-day events throughout the Mediterranean region but increases for sub-daily events. For both types of events the most extreme events in terms of size, severity and duration occur during the scenario period. This work has been conducted within the EU project RAIN (Risk Analysis of Infrastructure Networks in response to extreme weather).