engleski

Variability and projected climate change of precipitation indices over Croatia in a EURO-­ CORDEX ensemble

Performance of regional climate models (RCMs) from the EURO-CORDEX initiative is examined in terms of various precipitation indices. We focus on those RCMs that provided pairs of 50-km and 12.5-km simulations over Europe forced by historical and RCP-scenario simulations of the CMIP5 global climate models (GCMs). In addition to an overview for European domain, we focus on Croatia and surrounding region which is characterized by a complex orography and coastline. In this sub-region, a possible added value attained by the 12.5-km simulations relative to 50-km simulations can be detected in terms of total precipitation amounts and associated indices. Total precipitation is decomposed into the number of wet days (when precipitation amount is over a specific threshold) and a simple daily intensity index (mean total precipitation amount over wet days only). A comparison of the modelled total precipitation against the E-OBSv11 data for the historic period 1971-2000 reveals the spread of RCMs from the observations. For example, for the RegCM4 model (DHMZ-RegCM4), it was found that the model strongly overestimates the number of wet days (especially at 12.5 km), but it is relatively close to observations in terms of daily intensity index. In most simulations with both spatial resolutions, the change in total precipitation and associated indices between the historic period and the near-future period (2021-2050) is generally lower than the amplitude of systematic errors. For the pairs of RCMs and GCMs using several RCP scenarios (e.g. SMHI-RCA4), a weak sensitivity to the RCP scenario is found. This can be expected since statistically significant changes in precipitation over relatively large areas do emerge only in the later decades of the 21st century. The existence of non-negligible systematic errors in some RCMs indicates that additional customization of the model setup and/or more work on the model development is needed. In addition, an increase of RCMs’ horizontal resolution and application of more comprehensive parameterizations must be complemented by availability of high-quality high-resolution observational datasets.

climate change; precipitation; wet days; a simple daily intensity index

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