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<p>The Northeast Cold Vortex (NECV) is a deep cold-core vortex system prevalent over Northeast China and surrounding areas. It often triggers disastrous weather in Eastern China, such as prolonged heavy rainfall and severe cold surge. Therefore, enhancing the understanding of NECV’s mechanisms and improving the prediction capabilities are essential for disaster prevention and mitigation. This study proposes a NECV Frequency Index (NECVI) based on an improved objective identification method, revealing pronounced month-to-month differences in the spatiotemporal distribution of NECV activity from May to July. In May, the NECV activity center is near the Sea of Japan, modulated by two Rossby wave trains originating from North Atlantic. Maximum frequency of NECV is observed over the mid-southern Northeast China in June, driven by Rossby wave train originated from eastern Europe and Pacific-North America-like teleconnection induced by tropical central-eastern Pacific SST. In July, the NECV activity center shifts to Korea, mainly affected by the Rossby wave train propagating along the great-circle path from the North Atlantic to Northeast Asia. By tracing the origins of these physical factors, 1 or 2 physically meaningful predictors were selected for the NECVI in each month and numerical experiments were designed to verify their causal relationships with NECV. Based on the selected predictors, three physics-based prediction models for NECVI are established which achieve encouraging independent prediction skills with temporal correlation coefficients of 0.61, 0.69, and 0.71 for May, June, and July, respectively. Except for May, these models outperform the fifth generation of ECMWF’s seasonal forecast model, providing a valuable reference for the seasonal predictability of NECV.</p>

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Physics-based predictions of month-by-month variation in northeast cold vortex frequency during its peak season

  • 期刊论文

  • 发表日期：

    2026年5月28日

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  • Wenda Qu,
  • Juan Li,
  • Shiqi Xu,
  • Yihe Fang,
  • Zhiwei Zhu

摘要

The Northeast Cold Vortex (NECV) is a deep cold-core vortex system prevalent over Northeast China and surrounding areas. It often triggers disastrous weather in Eastern China, such as prolonged heavy rainfall and severe cold surge. Therefore, enhancing the understanding of NECV’s mechanisms and improving the prediction capabilities are essential for disaster prevention and mitigation. This study proposes a NECV Frequency Index (NECVI) based on an improved objective identification method, revealing pronounced month-to-month differences in the spatiotemporal distribution of NECV activity from May to July. In May, the NECV activity center is near the Sea of Japan, modulated by two Rossby wave trains originating from North Atlantic. Maximum frequency of NECV is observed over the mid-southern Northeast China in June, driven by Rossby wave train originated from eastern Europe and Pacific-North America-like teleconnection induced by tropical central-eastern Pacific SST. In July, the NECV activity center shifts to Korea, mainly affected by the Rossby wave train propagating along the great-circle path from the North Atlantic to Northeast Asia. By tracing the origins of these physical factors, 1 or 2 physically meaningful predictors were selected for the NECVI in each month and numerical experiments were designed to verify their causal relationships with NECV. Based on the selected predictors, three physics-based prediction models for NECVI are established which achieve encouraging independent prediction skills with temporal correlation coefficients of 0.61, 0.69, and 0.71 for May, June, and July, respectively. Except for May, these models outperform the fifth generation of ECMWF’s seasonal forecast model, providing a valuable reference for the seasonal predictability of NECV.