Juzbašić et al. (2025) Impact of global warming on precipitation extremes based on the design frequencies over South Korea

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-12-01
• Authors: Ana Juzbašić, Changyong Park, Dong‐Hyun Cha, Joong-Bae Ahn, Eun‐Chul Chang, Seung‐Ki Min, Youngeun Choi, Young‐Hwa Byun
• DOI: 10.1016/j.ejrh.2025.103021

Research Groups

• Department of Civil, Urban, Earth and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
• Department of Atmospheric Sciences, Pusan National University, Busan, Republic of Korea
• Department of Atmospheric Science, Kongju National University, Kongju, Republic of Korea
• Division of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea
• Department of Geography, Konkuk University, Seoul, Republic of Korea
• National Institute of Meteorological Sciences, Seogwipo, Republic of Korea

Short Summary

This study evaluates and analyzes future changes in precipitation extremes over South Korea using bias-corrected regional climate models and generalized extreme value theory. It finds that return values for extreme precipitation are projected to significantly increase, especially for longer return periods and under high-emission scenarios, necessitating the use of future projections for flood defense planning.

Objective

• To provide insights into biases in precipitation projections over South Korea and demonstrate the necessity of bias correction for precipitation extremes.
• To analyze possible future changes in spatially detailed extreme precipitation events using regional climate models under different emission scenarios.

Study Configuration

• Spatial Scale: South Korea (125–131°E, 33–39°N), with model data regridded to a 0.25° × 0.25° resolution.
• Temporal Scale: Daily precipitation data for boreal summer (June–July–August, JJA) across four 25-year periods: historical (1981–2005), near future (2025–2049), middle future (2050–2074), and far future (2075–2099).

Methodology and Data

• Models used:
  • 15 GCM-RCM chains from the CORDEX-EA Phase II project.
  • GCMs: GFDL-ESM-2M, HadGEM2-AO, MPI-ESM-LR (CMIP5, RCP scenarios); UKESM (CMIP6, SSP scenarios).
  • RCMs: WRF v.4, RegCM v.4, MM5 v.5, CCLM v.5, HadGEM3-RA, GRIMs (all at 25 km resolution).
  • Bias correction: Quantile Delta Mapping (QDM).
  • Extreme value analysis: Generalized Extreme Value (GEV) theory (block maxima approach, specifically Gumbel distribution for daily maximum precipitation, Rx1d).
  • Scenarios: Low emission (RCP2.6 and SSP1-2.6) and high emission (RCP8.5 and SSP5-8.5) multi-model ensembles (MME).
• Data sources:
  • Observational: Asian Precipitation - Highly-Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) dataset (0.25° × 0.25° grid, daily).
  • Model: CORDEX-EA Phase II project data.

Main Results

• Raw model simulations exhibited significant biases in precipitation extremes over South Korea (area-averaged bias from -9.4% to +48.1%), which were effectively reduced by Quantile Delta Mapping (QDM) to under 3.5% and aligned interannual variability with observations.
• Future projections show a consistent increase in return values (RVs) for all return periods (1 to 100 years) across South Korea.
• The magnitude of increase is more pronounced for longer return periods (e.g., RV100) and under high-emission scenarios, particularly by the end of the century.
• Under low-emission scenarios, return values are projected to increase by approximately 10%.
• Under high-emission scenarios by the end of the century (2075–2099), area-averaged RV30 is projected to increase by 35.8%, and RV100 by 38%.
• Spatially, the largest increases in RVs are projected for coastal and lowland areas, while mountainous regions show comparatively smaller increases.
• The likelihood of daily maximum precipitation (Rx1d) exceeding historical RV30 and RV100 thresholds is projected to increase, especially in high-emission scenarios, indicating a higher probability of more frequent and intense extreme events.

Contributions

• Demonstrated the critical need for bias correction in regional climate model projections of precipitation extremes over South Korea.
• Provided detailed spatial and temporal projections of future extreme precipitation return values, highlighting the disproportionate increase in longer return periods under climate change.
• Emphasized the importance of using future projected return values, rather than historical records, for designing long-term flood defense systems, urban drainage, and agricultural planning to avoid underestimation of future risks.
• Contributed to the understanding of regional climate change impacts on extreme hydrological events in a vulnerable region.

Funding

• Korea Meteorological Administration Research and Development Program (Grant RS-2024–00403386)
• Korea Environment Industry & Technology Institute (KEITI) through "Climate Change R&D Project for New Climate Regime," funded by Korea Ministry of Environment (MOE) (2022003560002)

Citation

@article{Juzbašić2025Impact,
  author = {Juzbašić, Ana and Park, Changyong and Cha, Dong‐Hyun and Ahn, Joong-Bae and Chang, Eun‐Chul and Min, Seung‐Ki and Choi, Youngeun and Byun, Young‐Hwa},
  title = {Impact of global warming on precipitation extremes based on the design frequencies over South Korea},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.103021},
  url = {https://doi.org/10.1016/j.ejrh.2025.103021}
}