Role of intraseasonal oscillation in the impact of western North Pacific warm pool on rainfall extremes in Yangtze River Basin

IF 4.4 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research Pub Date : 2025-09-02 DOI:10.1016/j.atmosres.2025.108457

Xuchen Fan , Fang Zhou , Botao Zhou , Jian Shi , Zuxiang Yang , Ting Yang , Zhongkai Bo , Na Wang

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引用次数: 0

Abstract

The Yangtze River Basin (YRB), home to millions of people and vital farmlands, faces increasing flood risks due to extreme summer rainfall. This study demonstrated that the western North Pacific warm pool (WNPWP) can exert significant impacts on extreme precipitation in YRB through modulating atmospheric intraseasonal activities over the northwestern Pacific, which operates on 25–80-day timescales. Extreme precipitation occurs preferentially during warm WNPWP summers compared to cold WNPWP summers owing to that intraseasonal oscillation (ISO) over the northwestern Pacific is more likely to induce extreme rainfall over the YRB during warm WNPWP summers than cold WNPWP summers. The underlying mechanism involves enhanced southwesterly moisture transport by the anomalous anticyclone over the northwestern Pacific driven by the ISO in its specific phases. Crucially, this transport intensifies remarkably during warm WNPWP summers due to the strengthened anticyclonic background manifested as the westward extension of the Western Pacific Subtropical High (WPSH) in response to warm WNPWP conditions, which is statistically tied to preceding El Niño-Southern Oscillation (ENSO) events.

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季节内振荡在北太平洋西部暖池对长江流域极端降水影响中的作用

长江流域是数百万人口和重要农田的家园，由于夏季极端降雨，长江流域面临越来越大的洪水风险。研究表明，北太平洋西部暖池（WNPWP）可以通过调节西北太平洋大气季内活动对西北太平洋极端降水产生显著影响，其时间尺度为25 ~ 80天。由于西北太平洋的季内振荡（ISO）在暖夏季比冷夏季更有可能诱发YRB极端降水，因此与冷夏季相比，极端降水优先发生在暖夏季。其潜在机制涉及由ISO在其特定阶段驱动的西北太平洋上的异常反气旋增强了西南水汽输送。至关重要的是，由于西太平洋副热带高压（WPSH）向西扩展，西太平洋副热带高压（WPSH）对西太平洋副热带高压的响应增强了反气旋背景，这种输送在温暖的西太平洋副热带高压夏季显著增强，这在统计上与之前的El Niño-Southern涛动（ENSO）事件有关。

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来源期刊

Atmospheric Research 地学-气象与大气科学

CiteScore

9.40

自引率

10.90%

发文量

460

审稿时长

47 days

期刊介绍： The journal publishes scientific papers (research papers, review articles, letters and notes) dealing with the part of the atmosphere where meteorological events occur. Attention is given to all processes extending from the earth surface to the tropopause, but special emphasis continues to be devoted to the physics of clouds, mesoscale meteorology and air pollution, i.e. atmospheric aerosols; microphysical processes; cloud dynamics and thermodynamics; numerical simulation, climatology, climate change and weather modification.