| 两类El Niño不同衰减型的演变特征及其与我国夏季降水的联系 |
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| 引用本文： | 陈圣劼,何金海.两类El Niño不同衰减型的演变特征及其与我国夏季降水的联系[J].海洋学报,2017,39(1):11-27. |
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| 作者姓名： | 陈圣劼 何金海 |
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| 作者单位： | 1.江苏省气象台, 江苏 南京 210008 |
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| 基金项目： | 国家重点基础研究发展计划（973计划）子课题——“热带太平洋海洋环流与暖池的结构特征、变异机理和气候效应”（2012CB417403）。 |
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| 摘 要： | 利用中国气象局743站日降水、NCEP-/NCAR大气环流、英国气象局Hadley中心全球月平均海表温度（SST）等资料,探讨了两类El Niño不同衰减型的演变特征及其对衰减阶段夏季（6-8月）我国降水异常分布的可能影响。根据海表温度异常（SSTA）沿赤道（5°S~5°N）的演变特征,EP-El Niño存在两种衰减型:自东向西（E-W）衰减（大于0.5℃的海温正距平首先在南美沿岸消失,并向西扩展）和自西向东（W-E）衰减（大于0.5℃的海温正距平首先在赤道中太平洋消失,并向东扩展）;CP-El Niño存在3种衰减方式:对称（S）衰减（赤道中太平洋暖海温的发展和衰减关于某一峰值对称）、延迟（P）衰减（衰减阶段紧接着呈现EP-El Niño分布）、突然（A）衰减（衰减阶段紧接着发生EP-La Niña事件）。对于EP-El Niño,在华北、华南、长江和黄河（简称两河）之间及两河的上游地区,E-W与W-E衰减阶段夏季降水呈现完全相反的异常分布特征。E-W衰减阶段夏季两河之间及上游地区偏旱的可能性显著增大,华北地区降水异常偏多,长江以南略偏多;而W-E衰减阶段夏季,两河之间及上游地区降水偏多,降水异常大值中心主要位于沿江地区,华南大部和华北地区降水明显偏少。对于CP-El Niño的3种衰减方式:夏季降水异常大值带在S衰减方式下主要位于黄河和淮河之间;在P方式衰减时,出现在长江流域;而在A型衰减时,主要位于黄河下游地区。S和A衰减方式下,东北大部尤其东北北部降水偏少,而处于P衰减时,东北大部降水明显偏多;在西南地区,S衰减时夏季降水总体偏多,A衰减时情况相反;在西北北部地区,A衰减时偏旱,而S和P衰减时降水总体偏多。不同的衰减方式均对应不同的降水异常空间分布,区分衰减型使得两类El Niño次年我国夏季降水异常显著区的分布范围和信号强度均较未区分衰减型时有较好的改善,为我国汛期降水短期气候预测工作提供了重要依据。
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| 关 键 词： | 两类ElNiño 不同衰减型 演变特征 夏季降水 |
| 收稿时间： | 2016/5/12 0:00:00 |
| 修稿时间： | 2016/7/15 0:00:00 |
Different decaying characteristics for two types of El Niño and their relationships with the summer rainfall in China |
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| Chen Shengjie and He Jinhai.Different decaying characteristics for two types of El Niño and their relationships with the summer rainfall in China[J].Acta Oceanologica Sinica (in Chinese),2017,39(1):11-27. |
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| Authors: | Chen Shengjie and He Jinhai |
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| Affiliation: | 1.Jiangsu Meteorological Observatory, Nanjing 210008, China2.Key Laboratory of Meteorological Disaster of NUIST, Nanjing 210044, China |
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| Abstract: | Different decaying characteristics for two types of El Niño and their relationships with the summer rainfall in China were investigated by using 743 stations daily precipitation data from China Meteorological Administration, NCEP circulation reanalysis datasets and the monthly mean Met Office Hadley Center sea surface temperature (SST) analyses data. Based on the evolution of the SST anomalies (SSTA) across the equator(5°S-5°N), two types of decaying patterns are identified for EP-El Niño:(1) An evolution pattern that SSTA decaying from east to west (E-W). The positive SSTA larger than 0.5℃ first disappear in offshore of South America and the disappearance extends to the west. (2) An evolution pattern that SSTA decaying from west to east (W-E). The positive SSTA larger than 0.5℃ first disappear in the central Pacific and the disappearance extends to the east. The decaying evolution of CP-El Niño is classified into three patterns:(1) A symmetric (S)-decaying pattern whose SSTA grows and decays symmetrically with respect to a peak phase, (2) A prolonged(P)-decaying pattern that is followed by a EP-El Niño type, (3) An abrupt(A)-decaying pattern that is followed by a EP-La Niña type. In the following summer of EP-El Niño in two different decaying patterns, there are almost completely opposite rainfall anomalies in North China, South China,the region between and the upstream area of the Yangtze River and the Yellow River Valley (they are called the Two River for short). In the following summer for E-W pattern, suppressed rainfall appears in the region between and the upstream area of the Two River, while the rainfall in North China is abundant and rainfall of the area to the south of the Yangtze River is slightly more. However, there are significantly positive anomalies in the region between and the upstream area of the Two River with the center of positive anomalies located along the Yangtze River, but the negative rainfall anomalies in most region of South China and North China for W-E pattern. As for three decaying patterns of CP-El Niño, the positive anomalies are present in the region between the Huaihe River and the Yellow River Valley for S pattern, in the Yangtze River Valley for P pattern, while in the lower reaches of the Yellow River for A pattern. Rainfall in the Northeast China, especially in the northern of Northeast China, is below normal for S and A pattern, while above normal for P pattern. In the Southwest China, wet (dry) signal appears for S (A) pattern. And in the northern of Northwest China,there is less (more) precipitation for A pattern (S and P pattern). Different distribution of summer rainfall anomalies in the decaying phase of El Niño is closely associated with their different decaying patterns. When inspecting the impacts of the two types of El Niño on the following summer rainfall, it would be better to consider their different decaying patterns in view of the larger significant area and T-inspection value of rainfall anomalies. All these will provide important reference for the short-term climate prediction of summer rainfall. |
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| Keywords: | two "flavors" of El Niño different decaying patterns evolution characteristics summer rainfall |
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