| 超强厄尔尼诺事件对中国东部春夏季极端降水频率的影响 |
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| 引用本文： | 刘明竑,任宏利,张文君,任鹏飞.超强厄尔尼诺事件对中国东部春夏季极端降水频率的影响[J].气象学报,2018,76(4):539-553. |
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| 作者姓名： | 刘明竑 任宏利 张文君 任鹏飞 |
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| 作者单位： | 1.南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心, 南京, 210044 |
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| 基金项目： | 公益性（气象）行业专项项目（GYHY201506013）、全球变化与海气相互作用专项（GASI-IPOVAI-03）、国家自然科学基金项目（41675073）。 |
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| 摘 要： | 利用中国国家气象信息中心提供的中国地面逐日降水0.5°×0.5°格点数据集，研究了超强厄尔尼诺事件衰减年春、夏季中国东部极端降水发生概率的变化，并通过诊断超强厄尔尼诺自身及其衍生模态各自的水汽输送和垂直运动特征，探讨了超强厄尔尼诺事件对中国东部极端降水的影响机制。结果表明，超强厄尔尼诺事件衰减年春季，整个中国东部尤其是江淮以北地区，极端降水事件发生概率显著增大。同年夏季，长江流域极端降水发生概率比常规年份高出近1倍，而在华南和华北地区则相对减小。诊断分析显示，春季超强厄尔尼诺自身及其与热带太平洋地区年循环相互作用衍生出的组合模态（C-mode）均对降水的环流背景影响显著，热带太平洋西北部低空存在强盛的反气旋性异常环流，导致大量水汽在中国东部汇聚并上升，有利于该地区极端降水事件的发生。夏季，厄尔尼诺事件已经消亡，但与C-mode影响相关联的西北太平洋异常反气旋环流仍然存在，长江流域维持极端降水事件发生的有利条件。此外，研究也显示，超强厄尔尼诺事件衰减年春、夏季中国东部对流层中上层持续有异常经向风活动，频繁的南北冷暖气流交汇可能导致强对流事件发生次数增多，这也为该区域极端降水的频发提供了支持。
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| 关 键 词： | 超强厄尔尼诺 极端降水 ENSO衍生模态 C-mode 中国东部 |
| 收稿时间： | 2017/11/16 0:00:00 |
| 修稿时间： | 2018/3/21 0:00:00 |
Influence of super El Niño events on the frequency of spring and summer extreme precipitation over eastern China |
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| LIU Minghong,REN Hongli,ZHANG Wenjun and REN Pengfei.Influence of super El Niño events on the frequency of spring and summer extreme precipitation over eastern China[J].Acta Meteorologica Sinica,2018,76(4):539-553. |
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| Authors: | LIU Minghong REN Hongli ZHANG Wenjun and REN Pengfei |
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| Institution: | Key Laboratory of Meteorological Disaster, Ministry of Education/International Joint Laboratory on Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China;Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China,Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China;CMA-NJU Joint Laboratory for Climate Prediction Studies, Nanjing 210023, China,Key Laboratory of Meteorological Disaster, Ministry of Education/International Joint Laboratory on Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China and Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081, China;Chinese Academy of Meteorological Sciences, Beijing 100081, China |
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| Abstract: | Features and mechanisms of the probability changes of spring and summer extreme precipitation during super El Niño events are investigated using the 0.5°×0.5° resolution China daily precipitation data from the National Meteorological Information Center. Through analyzing the water vapor transport and vertical motion characteristics contributed by the super El Niño and its derived mode, the mechanism of super El Niño impacts on extreme precipitation over eastern China are discussed. The results show that during the decaying phase of the super El Niño event, the occurrence probability of spring extreme precipitation increases significantly over the whole eastern China, especially to the north of the Yangtze-Huai River Valley. In summer, the probability is almost doubled that in regular years over the Yangtze River Valley, whereas it decreases sharply over southern and northern China. Physical analysis indicates that in spring, the super El Niño itself and the combination mode (C-mode) derived from its nonlinear interaction with the tropical Pacific annual cycle both have significant impacts on the anomalous circulation background, i.e., the strong anti-cyclonic circulation anomaly over the northwestern Pacific leads to abundant moisture convergence and ascending motion over eastern China, which is conducive to the occurrence of the observed extreme precipitation. In the subsequent summer, the super El Niño event has disappeared, but the anomalous Northwest Pacific anti-cyclonic circulation associated with the C-mode still exists, and the favorable condition for extreme precipitation maintains over the Yangtze River Valley. Additionally, in spring and summer, daily meridional wind anomalies in the mid-upper troposphere over eastern China are exceptionally active during the super El Niño events, and the frequent meridional convergence of cold air from north and warm moisture from south could lead to enhanced convective events, which may also contribute to the increased occurrence of extreme precipitation. |
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| Keywords: | Super El Niño event Extreme precipitation ENSO derived mode C-mode Eastern China |
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