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<p>In this research, we investigate the influence of the Northeast China Cold Vortex (NCCV) on the pre-flood season precipitation in South China (PSC) over the past six decades and corresponding mechanisms, using the monthly precipitation observations in South China and the fifth-generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis data for the period 1961–2020. The results indicate that the NCCV–PSC relationship exhibits pronounced interdecadal variability, and an abrupt shift from a weak correlation to a significant negative correlation occurred around 1998. After the abrupt shift, the PSC was jointly modulated by the mid- to high-latitude Rossby wave train and the low-level southwesterly wind over South China. In years with more PSC (weak NCCV years), a “− + − +” wave train persisted at 500&#xa0;hPa over mid- to high-latitudes, accompanied by a weakened NCCV, prominent negative geopotential height anomalies over Lake Baikal and intensified northwesterly airflow that favored the southward intrusion of cold air. Additionally, the western Pacific subtropical high (WPSH) was westward and stronger. Coupled with enhanced southwesterly water vapor transport, this atmospheric circulation configuration facilitated the persistent convergence of cold air and water vapor over South China to produce more PSC. Sea surface temperature anomalies in the tropical North Atlantic, tropical eastern and western Pacific and the Kuroshio Extension region from January to March modulated the NCCV intensity, the position and strength of the WPSH, and moisture transport by motivating mid- to high-latitude teleconnection wave trains, ultimately resulting in PSC anomalies. Sensitivity experiments basically reproduce the observed patterns.</p>

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New relationship and mechanisms between Northeast China Cold Vortex and pre-flood season precipitation in South China under global warming

  • 期刊论文

  • 发表日期：

    2025年11月4日

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  • Baihui Guo,
  • Yihe Fang,
  • Yitong Lin,
  • Yiqiu Yu,
  • Chunyu Zhao,
  • Yu Zhang,
  • Yamin Hu,
  • Mingsheng Wang

摘要

In this research, we investigate the influence of the Northeast China Cold Vortex (NCCV) on the pre-flood season precipitation in South China (PSC) over the past six decades and corresponding mechanisms, using the monthly precipitation observations in South China and the fifth-generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis data for the period 1961–2020. The results indicate that the NCCV–PSC relationship exhibits pronounced interdecadal variability, and an abrupt shift from a weak correlation to a significant negative correlation occurred around 1998. After the abrupt shift, the PSC was jointly modulated by the mid- to high-latitude Rossby wave train and the low-level southwesterly wind over South China. In years with more PSC (weak NCCV years), a “− + − +” wave train persisted at 500 hPa over mid- to high-latitudes, accompanied by a weakened NCCV, prominent negative geopotential height anomalies over Lake Baikal and intensified northwesterly airflow that favored the southward intrusion of cold air. Additionally, the western Pacific subtropical high (WPSH) was westward and stronger. Coupled with enhanced southwesterly water vapor transport, this atmospheric circulation configuration facilitated the persistent convergence of cold air and water vapor over South China to produce more PSC. Sea surface temperature anomalies in the tropical North Atlantic, tropical eastern and western Pacific and the Kuroshio Extension region from January to March modulated the NCCV intensity, the position and strength of the WPSH, and moisture transport by motivating mid- to high-latitude teleconnection wave trains, ultimately resulting in PSC anomalies. Sensitivity experiments basically reproduce the observed patterns.