Ma et al. (2025) Interdecadal shift of the dipole pattern in summer persistent extreme precipitation over Southwest China around 2003 and its possible causes

Identification

• Journal: Atmospheric Research
• Year: 2025
• Date: 2025-10-06
• Authors: Xiaoyi Ma, Ke Fan, Zhiqing Xu
• DOI: 10.1016/j.atmosres.2025.108538

Research Groups

• Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
• School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
• Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science & Technology, Nanjing, China
• University of Chinese Academy of Sciences, Beijing, China

Short Summary

This study investigates the interdecadal shift around 2003 of the leading mode of summer persistent extreme precipitation (PEP) over Southwest China (SWC), which exhibits a north-south dipole pattern, and attributes this shift to interactions between atmospheric circulation anomalies, southern European soil moisture, Barents-Kara Sea sea ice concentration, and Tibetan Plateau thermal feedback.

Objective

• To investigate the interdecadal variability of the leading mode of summer persistent extreme precipitation (PEP) over Southwest China (SWC) and its associated mechanisms.

Study Configuration

• Spatial Scale: Southwest China (SWC) as the primary region of interest, with teleconnections extending across Eurasia, southern Europe, the Barents-Kara Sea, and the Tibetan Plateau.
• Temporal Scale: Summer season; interdecadal variability, specifically focusing on a shift around 2003.

Methodology and Data

• Models used: Numerical simulations (no specific model name provided).
• Data sources: Observational diagnostics (no specific datasets mentioned, but implies real-world measurements).

Main Results

• The leading mode of summer SWC persistent extreme precipitation (PEP) exhibits a north-south dipole pattern.
• This dipole pattern underwent an interdecadal shift around 2003, transitioning from a north-negative–south-positive pattern to a north-positive–south-negative pattern.
• An anomalous cyclone over Northeast to North China and an anticyclone over southern China in the lower troposphere trigger the PEP pattern by inducing moisture convergence (divergence) over northern (southern) SWC.
• A Rossby wave train along the subtropical westerly jet over Eurasia provides favorable dynamic conditions for the dipole pattern.
• The atmospheric circulation anomalies are closely related to:
  • Reduced summer soil moisture over southern Europe, which enhances the meridional temperature gradient and atmospheric baroclinicity, intensifying synoptic-scale transient eddy activity and favoring an eastward-propagating wave train.
  • Summer Barents-Kara Sea (BKS) sea ice concentration (SIC) reduction, which weakens the meridional temperature gradient over mid-to-high latitude Eurasia, inducing local anomalous easterlies and promoting the European positive geopotential height anomaly and Rossby wave train.
  • Thermal feedback over the eastern Tibetan Plateau (TP), triggered by the Rossby wave train, which reinforces the anomalous atmospheric pattern favoring the dipole PEP over SWC.

Contributions

• Identifies and characterizes an interdecadal shift in the leading mode of summer persistent extreme precipitation over Southwest China around 2003.
• Elucidates the complex interplay of remote drivers (southern European soil moisture, Barents-Kara Sea SIC) and regional feedback (eastern Tibetan Plateau thermal feedback) in modulating this interdecadal shift and the associated atmospheric circulation anomalies.
• Provides valuable insights into the climatic characteristics and physical mechanisms of summer persistent extreme precipitation over SWC, which is crucial for disaster prevention.

Funding

• Not explicitly mentioned in the provided text.

Citation

@article{Ma2025Interdecadal,
  author = {Ma, Xiaoyi and Fan, Ke and Xu, Zhiqing},
  title = {Interdecadal shift of the dipole pattern in summer persistent extreme precipitation over Southwest China around 2003 and its possible causes},
  journal = {Atmospheric Research},
  year = {2025},
  doi = {10.1016/j.atmosres.2025.108538},
  url = {https://doi.org/10.1016/j.atmosres.2025.108538}
}