Wang et al. (2025) Isolating ENSO Influence on Eastern China Summer Rainfall Variability with Month-Dependent EOF Method: Observation–Model Synthesis

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Climate
• Year: 2025
• Date: 2025-12-01
• Authors: Xudong Wang, Shang‐Ping Xie, Zhaoyong Guan
• DOI: 10.1175/jcli-d-25-0234.1

Research Groups

Not specified in the abstract.

Short Summary

This study identifies two leading modes of interannual summer rainfall variability over eastern China using a month-dependent empirical orthogonal function (EOF) method, linking them to antecedent and concurrent El Niño–Southern Oscillation (ENSO) events, and interprets these modes using an atmospheric general circulation model.

Objective

• To identify and interpret the leading modes of interannual summer rainfall variability over eastern China and their relationship with tropical sea surface temperature (SST), particularly ENSO, using observations and an atmospheric general circulation model.

Study Configuration

• Spatial Scale: Eastern China (EC), Yangtze River, Yellow River, Indo–western Pacific Ocean.
• Temporal Scale: Interannual variability, summer rainfall (June to August), antecedent winter ENSO, concurrent developing El Niño, subseasonal evolution.

Methodology and Data

• Models used: Atmospheric General Circulation Model (AGCM) - 30-member ensemble simulation.
• Data sources: Observations (for rainfall variability), observed Sea Surface Temperature (SST) for model forcing. Empirical Orthogonal Function (EOF) method (month-dependent) for analysis.

Main Results

• Two leading modes of interannual rainfall variability over eastern China were identified using month-dependent EOFs.
• The first mode is linked to antecedent winter El Niño–Southern Oscillation (ENSO), showing a northward migration of increased rainfall across the Yangtze River from June to August, associated with an anomalous anticyclone in the lower troposphere (Indo–western Pacific Ocean capacitor effect).
• The second mode is related to concurrent developing El Niño, characterized by decreased rainfall along the Yangtze River in June, migrating northward to the Yellow River in July and August.
• The AGCM ensemble mean successfully captures the observed patterns of EC rainfall variability and associated lower tropospheric circulation anomalies.
• The first two modes explain 21.7% of the total rainfall variance in observations and 48.5% in the model ensemble mean.
• Atmospheric internal variability, as represented by the model ensemble spread, exhibits low-level circulation patterns broadly similar to those forced by SST.

Contributions

• Successfully distinguished concurrent and post-ENSO summers by considering subseasonal evolution of spatial patterns using month-dependent EOFs.
• Demonstrated that the spatial similarity between SST-forced and internal atmospheric modes, due to summer mean flow supporting barotropic energy conversion, makes isolating SST-forced variability challenging in limited observational records.
• Provided an interpretation of observed eastern China summer rainfall variability modes using a 30-member AGCM ensemble simulation.

Funding

Not specified in the abstract.

Citation

@article{Wang2025Isolating,
  author = {Wang, Xudong and Xie, Shang‐Ping and Guan, Zhaoyong},
  title = {Isolating ENSO Influence on Eastern China Summer Rainfall Variability with Month-Dependent EOF Method: Observation–Model Synthesis},
  journal = {Journal of Climate},
  year = {2025},
  doi = {10.1175/jcli-d-25-0234.1},
  url = {https://doi.org/10.1175/jcli-d-25-0234.1}
}