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<p>This study investigated the characteristics and mechanisms of summer regional persistent extreme precipitation events (RPEPEs) over South China (SC) modulated by distinct intensity regimes of 10–30-day intraseasonal oscillation (ISO). Diagnostic analyses revealed that the spatiotemporal evolution of RPEPEs exhibits robust phase-locking with the 10–30-day intraseasonal precipitation. By classifying RPEPEs into strong-ISO (SRPEPE) and weak-ISO (WRPEPE) composites based on the amplitude of 10–30-day filtered precipitation, we demonstrate a 14.6% enhancement in peak precipitation intensity during SRPEPEs compared to WRPEPEs. These distinct precipitation regimes are governed by fundamentally different Rossby wave teleconnection patterns over Eurasia. During SRPEPEs, a robust southeastward-propagating 10–30-day Rossby wave train originating from the Barents Sea traverses midlatitude Eurasia, effectively perturbing the northwestern Pacific upper-level circulation and establishing a favorable dynamic environment over SC. In contrast, WRPEPEs are associated with weaker eastward-propagating wave trains constrained along the subtropical jet stream. The horizontal convergence of background moisture driven by 10–30-day winds significantly amplifies lower-tropospheric humidity during SRPEPEs. The thermal advection of background temperature by 10–30-day geostrophic winds enhances baroclinic instability and vertical motion, intensifying precipitation under these moisture conditions.</p>

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Influence of Distinct Intraseasonal Oscillation Intensities on Regional Persistent Extreme Precipitation Events over South China

  • 期刊论文

  • 发表日期：

    2026年1月15日

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  • Wei Lu,
  • Yao Ha,
  • Yimin Zhu,
  • Haixia Dai,
  • Yijia Hu,
  • Yudi Liu,
  • Xiangrong Yang,
  • Zhong Zhong

摘要

This study investigated the characteristics and mechanisms of summer regional persistent extreme precipitation events (RPEPEs) over South China (SC) modulated by distinct intensity regimes of 10–30-day intraseasonal oscillation (ISO). Diagnostic analyses revealed that the spatiotemporal evolution of RPEPEs exhibits robust phase-locking with the 10–30-day intraseasonal precipitation. By classifying RPEPEs into strong-ISO (SRPEPE) and weak-ISO (WRPEPE) composites based on the amplitude of 10–30-day filtered precipitation, we demonstrate a 14.6% enhancement in peak precipitation intensity during SRPEPEs compared to WRPEPEs. These distinct precipitation regimes are governed by fundamentally different Rossby wave teleconnection patterns over Eurasia. During SRPEPEs, a robust southeastward-propagating 10–30-day Rossby wave train originating from the Barents Sea traverses midlatitude Eurasia, effectively perturbing the northwestern Pacific upper-level circulation and establishing a favorable dynamic environment over SC. In contrast, WRPEPEs are associated with weaker eastward-propagating wave trains constrained along the subtropical jet stream. The horizontal convergence of background moisture driven by 10–30-day winds significantly amplifies lower-tropospheric humidity during SRPEPEs. The thermal advection of background temperature by 10–30-day geostrophic winds enhances baroclinic instability and vertical motion, intensifying precipitation under these moisture conditions.