Record-breaking rainfall over the middle reaches of the Yangtze River in August 2021: Sub-seasonal perspective and its predictability
Record-breaking rainfall over the middle reaches of the Yangtze River in August 2021: Sub-seasonal perspective and its predictability
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2021年8月长江中游创纪录降雨：次季节视角及其预测
DOI：
10.1016/j.accre.2022.10.007
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发表时间：
2022-11
影响因子：
7.4
通讯作者：
Jinqing Zuo
中科院分区：
文献类型：
--
作者：
Li Guo;Jie Wu;Jinqing Zuo
2021年8月，长江中游地区出现特大暴雨，打破1981年以来的历史记录，引发严重洪涝灾害。控制环流系统和可能的可预测性来源的意外降雨仍然不清楚，特别是从亚季节的角度来看。结果表明，2021年8月连续性强降水过程具有明显的10-24 d和30-60 d的季节内振荡，并受热带和热带外环流系统的协同影响。尤其是东亚-太平洋遥相关型在7月下旬转为负位相，并维持整个8月，为热带水汽的北向输送和中高纬度冷空气的南侵提供了有利的背景条件。北半球夏季季节内振荡的第一模态（BSISO 1，周期为30-60 d）对降水的30 - 60 d振荡起主导作用，加强了热带水汽输送;西太平洋副高的准双周振荡和EAP的异常中纬度气旋对降水的10-24 d振荡起加强作用。此外，BSISO的第二模态（BSISO 2，周期为10-30 d）也可能使8月下旬10-24 d降水增强。S2 S模式对2021年8月持续性强降水的预报超前时间基本为1-2周，而EAP和BSISO 1是异常降水事件的主要预报源。这些结果突出了不同季节内振荡叠加在形成极端降水事件中的重要性，并表明如果S2 S模式中的集合成员能够根据其在关键可预报源上的表现合理地选择，则有可能提高极端事件的预报能力。
An extremely heavy rainfall cluster was observed over the middle reaches of the Yangtze River (MYR) in August 2021, breaking the historical record since 1981 and causing severe floods. The controlling circulation regime and possible predictability sources of the un-expected rainfall are still unclear, especially from a sub-seasonal perspective. Our results show that the successive heavy rainfall events in August 2021 had significant intraseasonal oscillations for 10–24 d and 30–60 d, and they were synergistically influenced by tropical and extra-tropical circulation regime. Above all, the East Asia–Pacific teleconnection pattern (EAP) turned into a negative phase in late July and maintained throughout August, providing favorable background conditions for the northward transport of tropical water vapor and the southward intrusion of cold air from mid-high latitudes. The 30–60-d oscillation of precipitation was dominated by the first mode of boreal summer intraseasonal oscillation (BSISO1, with 30–60-d period), which strengthened the tropical moisture transport, while the quasi-biweekly oscillation of the western Pacific subtropical high and the anomalous mid-latitude cyclone of EAP intensified the precipitation on the scale of 10–24 d. In addition, the second mode of BSISO (BSISO2, with 10–30-d period) may also intensify the 10–24-d precipitation in late August. The forecast leading time of the S2S models for the persistent heavy rainfall in August 2021 was basically 1–2 weeks, while the EAP and BSISO1 were revealed as the main predictable sources of the abnormal rainfall events. These results highlight the importance of superposition of different intraseasonal oscillations in forming the extreme rainfall event and demonstrate a potential chance to enhance the prediction skill of extreme event if the ensemble members in S2S models could be reasonably selected according to their performances on key predictability sources.
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影响因子：
3.2
作者：
Yuan Yuan-Yuan;Hui Gao;Weijing Li;Yanju Liu;Lijuan Chen;Bin Zhou;Yihui Ding
通讯作者：
Yuan Yuan-Yuan;Hui Gao;Weijing Li;Yanju Liu;Lijuan Chen;Bin Zhou;Yihui Ding
影响因子：
4.6
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
3.2
作者：
X. Liang;Lipeng Jiang;Yang Pan;C. Shi;Zhiquan Liu;Zijiang Zhou
通讯作者：
X. Liang;Lipeng Jiang;Yang Pan;C. Shi;Zhiquan Liu;Zijiang Zhou
影响因子：
4.6
作者：
R. Wu;Bin Wang
通讯作者：
R. Wu;Bin Wang