Alexandra Berényi

As a result of climate change, extreme weather phenomena are expected to become more frequent and severe, so adaptation in the future will be essential. Global and regional climate model simulations offer crucial insights into future climate change, forming the basis for planning and implementing adaptation and mitigation strategies. Therefore, evaluating these simulations is essential for generating reliable projections. This study assesses ten historical Euro‐CORDEX simulations using different combinations of Global and Regional Climate Models, validated against the E‐OBS dataset, which is derived from meteorological station measurements across Europe. All data are available at daily temporal resolution and interpolated to a 0.1° regular grid. The study analyses the period 1970–2005. For study areas, 14 plain regions were selected across Europe with an objective three‐step methodology based on elevation and geographical borders. Plain regions were defined as relatively flat areas below 200 m elevation. We calculated 11 climate indices; 8 of these are associated with extreme precipitation events, and for the evaluation we used four statistical metrics designed to assess the performance and capability of the model simulations. Based on these results and metrics, a model performance scoring system was established to rank and compare simulations and identify well‐performing models. This ranking methodology enhances the reliability of climate projections by highlighting models that perform best for specific regions or variables, thereby supporting more targeted and informed adaptation planning through reduced uncertainty and increased confidence in future outcomes. To test the sensitivity of model evaluation to the uncertainty originating from the selected reference data, an additional assessment was carried out in two specific regions using high‐resolution datasets (i.e., CARPATCLIM and ROCADA). Results indicate a clear overestimation of both non‐extreme and extreme precipitation in Euro‐ CORDEX simulations with distinct seasonal biases. A general overestimation is found across the domains in winter, while a substantial underestimation can be identified in the south‐eastern regions. Based on the model performance scores, different metrics yielded varying rankings of the models; thus, it is not possible to set an evident order of model simulations. The use of high‐resolution datasets confirmed the importance of incorporating additional observational data in areas with limited station coverage. Nevertheless, the models are generally capable of reproducing the patterns of historical precipitation conditions, and the ensemble is adequate for analysing the future climate.

The aim of our study is to analyse the spatial patterns and temporal trends of average and extreme precipitation events in a few selected plain regions between 1951 and 2019. Besides the Great Hungarian Plain we chose two plain regions located in the southern part of the continent (i.e. the Po Valley and the Romanian Plain) with the purpose of comparing similar geographical regions, and creating a scientific basis to comprehensively analyse the effects of climate change on economy, society, and nature. For choosing the plains, objective criteria were used, namely, (i) the elevation remains under 200 m throughout the defined area, and (ii) the difference between the neighbouring grid points within the plain region does not exceed 50 m. The analysis of extreme precipitation events was performed for annual periods by calculating 17 climate indices. Based on our research of the past, there is a clear increase in the frequency and intensity of extreme precipitation events, in the length of dry periods as well as in the occurrence of extreme weather events.

The effects of climate change on precipitation patterns can be observed on global scale, however, global climate change affects different regions more or less severely. Because of the high variability of precipitation in particular, future changes related to precipitation can be very different, even opposite on continental/regional scale. Even within Europe, the detected trends in precipitation patterns and extremes differ across the continent. According to climate model simulations for the future, Northern Europe is projected to become wetter, while the southern parts of the continent will tend to become drier by the end of the 21st century. The frequency and intensity of extreme precipitation will also increase in the whole continent. The possible shifts in precipitation patterns from wetter to drier conditions with fewer but increased extreme precipitation events can cause severe natural hazards, such as extended drought periods, water scarcity, floods and flash floods, therefore appropriate risk management is essential. For this purpose the analysis of possible hazards associated to specific precipitation-related weather phenomena is necessary and serves as key input.Since plain regions play an important role in agricultural economy and are more exposed to floods because of their geographic features and the gravitational movement of surface water, our primary goal was to examine temporal and spatial changes in extreme precipitation events and dry spells in three European lowlands, located in the southern part of the continent. We selected the following regions: the Po-Valley located in Italy with humid subtropical climate; the Romanian Plain in Romania, and the Pannonian Plain covering different parts of Hungary, Serbia, Slovakia, Croatia, Romania and Ukraine with humid continental climatic conditions.Precipitation time series were used from the E-OBS v.22 dataset on a 0.1° regular grid. The dataset is based on station measurements from Europe and are available from 1950 onward with daily temporal resolution. For the analysis of main precipitation patterns, dry spells and extreme events, we use 17 climate indices (most of them are defined by the Expert Team on Climate Change Detection and Indices, ECCDI). The analysis focuses on annual and seasonal changes in the three regions. The selected indices are capable to represent the differences and similarities between and within the plains. Our preliminary results show that the occurrence and intensity of extreme precipitation events increased in all regions, while the trends of duration and frequency of dry spells show both intra- and inter regional variability across the plains.