Hiraga et al. (2025) Impacts of Climate Change on Tropical Cyclones and associated Rainfall over South Korea: Storyline and Risk-based approaches

Identification

• Journal: Atmospheric Research
• Year: 2025
• Date: 2025-12-09
• Authors: Yusuke Hiraga, Jose Angelo Hokson, Bomi Kim, Yaewon Lee, Seong Jin Noh
• DOI: 10.1016/j.atmosres.2025.108685

Research Groups

• Department of Civil and Environmental Engineering, Tohoku University, Sendai, Japan
• Department of Civil Engineering, Kumoh National Institute of Technology, Gumi, South Korea

Short Summary

This study quantifies the impact of climate change on Typhoon Hinnamnor and its associated rainfall over South Korea using a storyline approach, and examines changes in the frequency and intensity of tropical cyclones affecting the region through a risk-based approach. It finds that future warming intensifies Hinnamnor-like typhoons and increases the frequency of violent typhoons, despite a decrease in overall tropical cyclone frequency, with significant implications for regional flood risk.

Objective

• To examine future climate change impacts on Typhoon Hinnamnor and its associated rainfall in South Korea.
• To assess broader changes in the frequency and tracks of super typhoons under warming climate conditions over the target region.

Study Configuration

• Spatial Scale:
  • Storyline approach: Nested WRF domains with horizontal resolutions of 15 km, 5 km, and 1.67 km, focusing on South Korea and the Nakdonggang basin.
  • Risk-based approach: Regional domain encompassing approximately 500 km of mainland South Korea (29.1°N to 43.6°N, 120.8°E to 134.6°E), extracted from global simulations.
• Temporal Scale:
  • Storyline approach: 48-hour accumulated precipitation (UTC 12:00 September 4th - 12:00 September 6th, 2022). Climate deltas for past (1860s: 1850–1869), current (2015–2024), and future (2050s: 2041–2060, and 2090s: 2081–2100) conditions under the SSP2–4.5 scenario.
  • Risk-based approach: Historical (1951–2010), +2 K warming (2030–2091), and +4 K warming (2050–2111) climate conditions.

Methodology and Data

• Models used:
  • Storyline approach: Advanced Research Version of the Weather Research and Forecasting Model (WRF), version 4.6.0. Climate deltas derived from multi-model mean of 12-29 CMIP6 models.
  • Risk-based approach: Large ensemble climate dataset from the Database for Policy Decision-Making for Future Climate Change (d4PDF), with approximately 60 km resolution.
• Data sources:
  • Storyline approach: NCEP GDAS FNL operational global analysis (initial and boundary conditions for WRF), JMA RSMC Tokyo - Typhoon Center best track dataset, Automatic Weather Station (AWS) and Automated Surface Observing System (ASOS) rain gauge data for verification.
  • Risk-based approach: WEBB et al. (2019) large ensemble Tropical Cyclone (TC) track dataset, extracted from d4PDF.

Main Results

• Storyline Approach (Typhoon Hinnamnor under 2090s SST, SSP2–4.5 scenario):
  • Maximum sustained wind speed increased by 15% (an increase of 10 m/s).
  • Minimum sea level pressure decreased by 2% (a decrease of 1700 Pa).
  • Basin-average rainfall over the Nakdonggang basin increased by 29.4%.
  • Accumulated Cyclone Energy (ACE) increased by 25.4%.
  • Typhoon track showed notable westward shifts, leading to increased land coverage.
  • Surface latent heat fluxes and Convective Available Potential Energy (CAPE) increased, driving intensification.
• Risk-based Approach (under +4 K warming climate):
  • Maximum sustained wind speed for Violent Typhoons increased by 14%.
  • Minimum sea level pressure for Violent Typhoons decreased by 1%.
  • Overall frequency of TCs affecting South Korea decreased by 36%.
  • Frequency of Violent Typhoons affecting South Korea increased by 27%.
  • Frequency of eastward-moving Violent Typhoons affecting South Korea also increased.
  • Ensemble-mean tracks showed an eastward shift from historical to +2 K climate, and a westward shift at higher latitudes from +2 K to +4 K climate.
• Consistency: The identified changes in TC intensity (maximum sustained wind speed and minimum sea level pressure) were comparable between the storyline and risk-based approaches.

Contributions

• Integrated both storyline (Pseudo-Global Warming) and risk-based approaches to provide a comprehensive assessment of climate change impacts on tropical cyclones affecting South Korea.
• Quantified the specific impacts of future warming scenarios (SSP2–4.5) on Typhoon Hinnamnor's intensity, track, and associated rainfall, including detailed spatial and temporal distributions, which is crucial for regional flood risk assessment.
• Demonstrated that while the overall frequency of TCs affecting South Korea may decrease, the frequency and intensity of more destructive Violent Typhoons are projected to increase under future warming.
• Provided insights into the physical mechanisms (e.g., latent heat flux, CAPE) driving changes in TC intensity and rainfall under different warming scenarios.
• Highlighted the robustness of findings by showing comparable changes in TC intensity between the storyline and risk-based methodologies.

Funding

• Habataku Research Grant for young faculty members in Tohoku University (Yusuke Hiraga).
• Joint Usage/Research Center for Interdisciplinary Large-scale Information Infrastructures (JHPCN) and High Performance Computing Infrastructure (HPCI) in Japan (Project ID: jh240013 Yusuke Hiraga).
• R&D project “Technology for Securing Water Resources Stability in Response to Future Change” (RS-2024-00332494) funded by the Korea Ministry of Environment (MOE) through KEITI.

Citation

@article{Hiraga2025Impacts,
  author = {Hiraga, Yusuke and Hokson, Jose Angelo and Kim, Bomi and Lee, Yaewon and Noh, Seong Jin},
  title = {Impacts of Climate Change on Tropical Cyclones and associated Rainfall over South Korea: Storyline and Risk-based approaches},
  journal = {Atmospheric Research},
  year = {2025},
  doi = {10.1016/j.atmosres.2025.108685},
  url = {https://doi.org/10.1016/j.atmosres.2025.108685}
}