Projected changes of mean and extreme precipitation in Hungary: comparison of raw and bias-adjusted EURO-CORDEX simulations

Climate change is one of the biggest threads to humanity, and its effects are already detected. According to the IPCC, not only hot extremes, but droughts and precipitation-related extremes have also become more frequent. The lack of precipitation means severe problem to the ecosystems, agriculture and human health, however, intense rainfalls can also cause damages, e.g. flash floods, which are one of the most devastating natural disasters. Therefore, it is important to know, how the precipitation is likely to change in the future.

The main goal of our research is to investigate the projected changes of precipitation over Hungary for the near future (2021–2050) and the far future (2070–2099) with respect to the reference period of 1976–2005. In addition, the aim of our study is to investigate how the choice of the reference dataset and different calibration periods affects the changes. For this purpose, the results of different datasets are compared: raw and bias-corrected RCM projections. In total three bias-corrected RCM based datasets are included in the present study: RCM projections available from the EURO-CORDEX initiative (using MESAN as reference data), the FORESEE-HUN database and an additional bias-corrected database, newly created for this research (referred to as BC-HUCLIM in the following). The bias-correction was carried out by applying the internationally widely used percentile-based quantile mapping method on a monthly level using the most accurate, quality controlled HuClim dataset as a reference. Each database contains the simulations of 5 RCMs (CCLM, HIRHAM, RACMO, RCA, REMO) from the framework of EURO-CORDEX at a horizontal resolution of 0.11° (about 12.5 km). Two Representative Concentration Pathway (RCP) scenarios are used: RCP4.5 and RCP8.5, respectively.

Beside the assessment of the mean precipitation characteristics on different time scales, the following extreme precipitation-related climate indices are analyzed: wet days, very heavy precipitation days, frequency of at least 50 mm 5-day precipitation total, the highest daily precipitation sum and extremely wet days. According to our results, the mean annual precipitation is expected to increase by 10% on lowland areas and by 30% in mountainous areas on average under the RCP8.5 scenario by the end of the 21st century. In the Northern Mountains, the most pronounced changes are shown by BC-HUCLIM, and the raw and bias-corrected RCM simulations using MESAN project the smallest increase. Under the RCP4.5 scenario, the changes remain below 20% and negligible differences are found between the databases. The greatest increase in the annual number of very heavy precipitation days is expected by BC-HUCLIM for the far future in the south-western part of Hungary.