Abstract
Abstract. Widespread flooding events are among the major natural hazards in central Europe. Such events are usually related to intensive, long-lasting precipitation over larger areas. Despite some prominent floods during the last three decades (e.g., 1997, 1999, 2002, and 2013), extreme floods are rare and associated with estimated long return periods of more than 100 years. To assess the associated risks of such extreme events, reliable statistics of precipitation and discharge are required. Comprehensive observations, however, are mainly available for the last 50–60 years or less. This shortcoming can be reduced using stochastic data sets. One possibility towards this aim is to consider climate model data or extended reanalyses. This study presents and discusses a validation of different century-long data sets, decadal hindcasts, and also predictions for the upcoming decade combined to a new large ensemble. Global reanalyses for the 20th century with a horizontal resolution of more than 100 km have been dynamically downscaled with a regional climate model (Consortium for Small-scale Modeling – CLimate Mode; COSMO-CLM) towards a higher resolution of 25 km. The new data sets are first filtered using a dry-day adjustment. Evaluation focuses on intensive widespread precipitation events and related temporal variabilities and trends. The presented ensemble data are within the range of observations for both statistical distributions and time series. The temporal evolution during the past 60 years is captured. The results reveal some long-term variability with phases of increased and decreased precipitation rates. The overall trend varies between the investigation areas but is mostly significant. The predictions for the upcoming decade show ongoing tendencies with increased areal precipitation. The presented regional climate model (RCM) ensemble not only allows for more robust statistics in general, it is also suitable for a better estimation of extreme values.
Highlights
Ongoing climate change affects the global scale and impacts the regional climate
Even though HYRAS was aggregated to the European observational data set (E-OBS)/regional climate model (RCM) grid, the more pronounced differences especially for the extremes might be a result of the higher resolution of the HYRAS data, which, in particular, is of greater relevance in the mountainous region of AL∗
We have presented the novel LAERTES-EU ensemble combining various regional climate model simulations done with COSMO-CLM to analyze long-term variability and trends of flood-related intensive areal precipitation across central Europe
Summary
Ongoing climate change affects the global scale and impacts the regional climate. The use of highresolution regional climate models (RCMs) instead of global data sets revealed a more detailed and orographically related spatial structure of the precipitation fields and trends (e.g., Feldmann et al, 2013). An increase of both areal mean precipitation and extremes in central Europe on the order of 5 %–10 % was found in RCM simulations by Feldmann et al (2013), which will continue with almost same magnitude for the decade. Which temporal evolution and variability of extreme areal precipitation over central Europe have manifested during the past?
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