Jeon et al. (2025) C4MIP-based projections of moisture convergence and extreme precipitation risks in East Asia

Identification

• Journal: Atmospheric Research
• Year: 2025
• Date: 2025-11-20
• Authors: Nayeon Jeon, Dasom Lee, Rackhun Son
• DOI: 10.1016/j.atmosres.2025.108637

Research Groups

• Department of Environmental Atmospheric Science, Pukyong National University, Republic of Korea
• Atmospheric Environment Research Institute, Pukyong National University, Republic of Korea

Short Summary

This study evaluates the performance of the Coupled Climate Carbon Cycle Model Intercomparison Project (C4MIP) in simulating vertically integrated moisture flux convergence (VIMFC) and projecting extreme precipitation risks over East Asia. It finds that C4MIP offers improved skill in capturing VIMFC patterns and projects intensified moisture convergence and elevated extreme precipitation risk over southeastern China and North Korea under a high-emission scenario.

Objective

• To analyze decadal trends and spatial patterns of moisture convergence-driven extreme precipitation over East Asia using the C4MIP multi-model ensemble.
• To assess future changes in extreme precipitation risk under climate change scenarios.

Study Configuration

• Spatial Scale: East Asia (110°E–150°E, 15°N–50°N), including the Korean Peninsula, Japan, and eastern China.
• Temporal Scale:
  • Historical period: 1980–2014
  • Future projection period: 2015–2100 (with sub-periods 2015–2045 for near-future and 2070–2100 for far-future extreme event analysis)

Methodology and Data

• Models used:
  • Coupled Climate-Carbon Cycle Model Intercomparison Project (C4MIP) multi-model ensemble (6 models)
    • Scenarios: hist-bgc (historical with biogeochemical feedbacks), ssp5–8.5-bgc (high-emission pathway with carbon cycle processes).
  • Coupled Model Intercomparison Project Phase 6 (CMIP6) multi-model ensemble (6 models)
    • Scenarios: historical, hist-GHG (greenhouse gas forcing only), hist-Nat (natural forcing only).
  • Variables calculated: Vertically Integrated Moisture Flux Convergence (VIMFC), Vertically Integrated Moisture Flux (VIMF).
  • Statistical metrics: Pearson correlation coefficient (R), Root Mean Square Error (RMSE), Skill Score (SS).
  • Extreme value analysis: Gumbel distribution for return periods.
  • Moisture budget: Precipitation (P) approximated as the sum of evaporation (E) and VIMFC (P ≈ E + VIMFC) to quantify VIMFC contribution.
• Data sources:
  • Reanalysis datasets: ERA5, MERRA-2, JRA-55, NCEP-NCAR Reanalysis 1.
  • Precipitation data: CMAP precipitation data.
  • Variables: Monthly fields of specific humidity, surface pressure, zonal (u) and meridional (v) wind components, and precipitation.
  • All model outputs and reanalysis data bilinearly interpolated to a uniform 1° × 1° grid.

Main Results

• C4MIP demonstrates improved skill in reproducing annual and seasonal VIMFC patterns over East Asia, particularly during periods of strong convergence/divergence (e.g., spring, autumn, winter).
• C4MIP achieved the lowest annual mean RMSE (12.45 × 10⁻⁶ kg m⁻² s⁻¹) and highest spatial correlation (R = 0.82) in spring compared to CMIP6 scenarios.
• However, C4MIP systematically underestimates the magnitude and interannual variability of extreme VIMFC during the historical period (e.g., ~23% for summer, ~15% for annual mean), likely due to carbon-vegetation coupling effects.
• Historically (1980–2014), VIMFC showed a net moisture export tendency, contributing to an average precipitation decline of 0.24% per year. Summer VIMFC accounted for over 35% of seasonal precipitation, but this contribution decreased by 0.11% per year.
• Future projections (2015–2100) under the SSP5-8.5-bgc scenario indicate statistically significant increases in VIMFC over southeastern China (110°E–120°E, 25°N–30°N) and North Korea, with reductions over South Korea and southern Japan.
• By 2100, 10-year return levels of VIMFC are projected to increase by approximately 6.91 × 10⁻⁶ kg m⁻² s⁻¹ (1.08-fold) over southeastern China and 3.15 × 10⁻⁶ kg m⁻² s⁻¹ (1.23-fold) over North Korea annually. Summer projections show even stronger intensification, with increases of approximately 9.25 × 10⁻⁶ kg m⁻² s⁻¹ and 9.12 × 10⁻⁶ kg m⁻² s⁻¹, respectively.
• The frequency of extreme precipitation events (exceeding the 99th percentile) in southeastern China shows a steady increase of approximately 0.6 events per decade. South Korea exhibits a decline until mid-century followed by a marked rise, while southern Japan shows a peak around 2040 followed by a decline.

Contributions

• Provides the first diagnostic evaluation of C4MIP's hydrological performance in simulating vertically integrated moisture flux convergence (VIMFC) and projecting extreme precipitation risks specifically for East Asia.
• Demonstrates the added value of C4MIP's integrated carbon cycle feedbacks for regional hydrological assessments, showing improved skill in capturing VIMFC patterns compared to CMIP6.
• Offers valuable insights for future regional climate projections and adaptation strategies in East Asia by identifying areas of increased extreme precipitation risk (southeastern China, North Korea) and contrasting regional trends (South Korea, southern Japan).
• Highlights limitations of current C4MIP scenarios, such as underestimation of extreme VIMFC magnitudes, prescribed CO₂ radiative effects, neglect of transient eddies, and restricted ensemble size, guiding future research directions.

Funding

• National Research Foundation of Korea (NRF) grant funded by Korea government (MSIT) (RS-2022-NR068509 and RS-2024-00343921).

Citation

@article{Jeon2025C4MIPbased,
  author = {Jeon, Nayeon and Lee, Dasom and Son, Rackhun},
  title = {C4MIP-based projections of moisture convergence and extreme precipitation risks in East Asia},
  journal = {Atmospheric Research},
  year = {2025},
  doi = {10.1016/j.atmosres.2025.108637},
  url = {https://doi.org/10.1016/j.atmosres.2025.108637}
}