Shen et al. (2025) Unravelling the future role of internal variability in South Asian near-surface wind speed

Identification

• Journal: Earth System Dynamics
• Year: 2025
• Date: 2025-11-03
• Authors: Cheng Shen, Hui‐Shuang Yuan, Zhibo Li, Jinling Piao, Youli Chang, Deliang Chen
• DOI: 10.5194/esd-16-1959-2025

Research Groups

• Regional Climate Group, Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden
• Department of Atmospheric Science, Yunnan University, Kunming, China
• State Key Laboratory of Earth System Numerical Modeling and Application, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
• Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
• College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
• Department of Earth System Science, Tsinghua University, Beijing, China

Short Summary

This study quantifies the role of internal variability, specifically the Interdecadal Pacific Oscillation (IPO), in modulating near-surface wind speed (NSWS) projections over South Asia, finding that accounting for IPO reduces projection uncertainty by 8% in the near future and 15% in the far future.

Objective

• Identify the leading mode of internal variability affecting near-future near-surface wind speed (NSWS) changes over South Asia.
• Quantify the uncertainties of NSWS projections associated with internal variability over South Asia.

Study Configuration

• Spatial Scale: South Asia (5–30° N, 65–90° E).
• Temporal Scale: Historical period (1970–2020 for reanalysis, 1850–2005 for model historical runs); Future period (2021–2099 for model projections), with specific focus on near-term (2021–2050) and far-term (2021–2095) future.

Methodology and Data

• Models used: Max Planck Institute Earth System Model (MPI-ESM) Large Ensemble (100 members).
• Data sources:
  • Reanalysis: JRA55 (Japanese Meteorological Agency), CRA40 (National Meteorological Information Center of the China Meteorological Administration), ERA5 (European Centre for Medium-Range Weather Forecasts atmospheric reanalysis fifth generation).
  • Simulations: MPI-ESM Large Ensemble (historical and RCP4.5/RCP8.5 scenarios).
  • Methods: Inter-member Empirical Orthogonal Function (EOF) analysis, linear regression to isolate IPO/AMO effects.

Main Results

• The MPI-ESM Large Ensemble successfully reproduces historical near-surface wind speed (NSWS) trends and large-scale circulation features over South Asia.
• Internal variability significantly impacts NSWS trends, with inter-member standard deviation comparable to the long-term trend.
• The Interdecadal Pacific Oscillation (IPO) is identified as the dominant mode of internal variability affecting NSWS in the near future, explaining 54.6% of the total inter-member variance.
• A positive IPO phase enhances regional westerly winds over South Asia, leading to increased NSWS, linked to a weakening of the Walker Circulation.
• Accounting for the IPO's influence reduces NSWS projection uncertainty by approximately 8% (standard deviation from 0.09 to 0.08 m/s per 30 years) in the near future (2021–2050).
• For the far future (2021–2095), removing the IPO's influence reduces projection uncertainty by 15%.
• The IPO's contribution represents 40% and 75% of the total internal variability in NSWS projections for the near and far future periods, respectively.
• The Atlantic Multidecadal Oscillation (AMO) shows a minimal contribution to NSWS changes over South Asia.

Contributions

• Provides the first systematic assessment and quantification of uncertainties in South Asian NSWS projections due to internal variability using a large ensemble.
• Identifies the Interdecadal Pacific Oscillation (IPO) as the primary mode of internal variability modulating South Asian NSWS projections.
• Quantifies the reduction in NSWS projection uncertainty (8% near-term, 15% long-term) by accounting for IPO, offering valuable insights for regional climate adaptation and wind energy development.
• Highlights the increasing and prolonged influence of the IPO on NSWS projections throughout the 21st century.

Funding

• Tsinghua University (100008001)
• Swedish Formas (2023-01648, 2020-00982)
• Swedish Research Council VR (2021-02163)
• Sven Lindqvists Forskningsstiftelse
• Stiftelsen Längmanska kulturfonden (BA24-0484)
• Stiftelsen Åforsk (24-707)
• Adlerbertska Forskningsstiftelsen (AF2024-0069)
• Innovation and Entrepreneurship Training Program for College Students of Yunnan University (S202310673266)
• Swedish National Strategic Research Area MERGE
• Publication funded by the Swedish Research Council and Formas.

Citation

@article{Shen2025Unravelling,
  author = {Shen, Cheng and Yuan, Hui‐Shuang and Li, Zhibo and Piao, Jinling and Chang, Youli and Chen, Deliang},
  title = {Unravelling the future role of internal variability in South Asian near-surface wind speed},
  journal = {Earth System Dynamics},
  year = {2025},
  doi = {10.5194/esd-16-1959-2025},
  url = {https://doi.org/10.5194/esd-16-1959-2025}
}