| 两类El Ni?o对应的印度洋偶极子事件的比较研究 |
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| 引用本文： | 钱景,李崇银,谭言科,桂发银,黎鑫.两类El Ni?o对应的印度洋偶极子事件的比较研究[J].热带气象学报,2017,33(4):467-477. |
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| 作者姓名： | 钱景 李崇银 谭言科 桂发银 黎鑫 |
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| 作者单位： | 1.解放军理工大学气象海洋学院，江苏 南京 211101 |
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| 基金项目： | 国家自然科学基金项目41490642国家自然科学基金项目41475070 |
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| 摘 要： | 利用多种大气和海洋再分析资料，采用合成分析及2.5层简化海洋模型数值模拟等方法，研究了1951—2012年期间，与东部和中部型El Ni?o事件相伴随的热带印度洋海温偶极子(Indian Ocean Dipole，IOD)出现时，热带印度洋海温异常增暖及其上空海气耦合特征的物理机制。结果表明:夏秋季节，伴随东部型El Ni?o而发生的IOD事件(EP-IOD)和伴随中部型El Ni?o而发生的IOD事件(CP-IOD)中，热带印度洋海温正异常的强度与空间分布具有很大差异。对于EP-IOD事件，夏季，海温正异常中心最先出现在热带西北印度洋；随后秋季，海温正异常向东南发展并扩大至热带中南印度洋，强度较强。对于CP-IOD事件，夏季和秋季，海温正异常中心都位于热带中南印度洋，呈东西向带状分布，但海温正异常强度较EP-IOD事件中弱。进一步分析表明，在EP-IOD事件中，夏季，热带西北印度洋海区西南季风偏弱，通过影响夹卷混合过程导致热带西北印度洋海温上升；秋季，热带西北印度洋上空的异常偏东风导致垂向夹卷混合的正异常，对热带西北印度洋增暖的维持起到重要作用；热带中南印度洋的增暖主要受赤道东南印度洋西传的暖性Rossby波影响。而在CP-IOD事件中，夏秋两季，热带中南印度洋海区出现显著的西北风异常，其上空风速的负异常是增温的主要原因；同时赤道东南印度洋西传的暖性Rossby波对热带中南印度洋的增暖也起到重要作用。
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| 关 键 词： | 两类El Ni?o 印度洋 IOD 季节演变 2.5层简化海洋模型 |
| 收稿时间： | 2016-08-28 |
COMPARING STUDY ON INDIAN OCEAN DIPOLE EVENTS ASSOCIATED WITH TWO TYPES OF EL NI?O |
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| Affiliation: | 1.College of meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101, China2.LASG, Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029, China |
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| Abstract: | Based on various reanalysis data of the atmosphere and sea, the mechanism of warming in tropical Indian Ocean and ocean-atmosphere coupled process between the IOD events that co-occur with the EP and CP El Ni?o in summer and autumn from 1951 to 2012 are studied using composite analysis and a 2.5 layer dynamic upper-ocean model. The result shows that the intensity and region of positive sea surface temperature anomoaly (SSTA) in tropical Indian Ocean have great diversity between EP El Ni?o (EP-IOD) and CP El Ni?o (CP-IOD) in summer and autumn. Positive SSTA of EP-IOD first appears in the tropical northwestern Indian Ocean in summer and then extends southeastward to the central Indian Ocean south of the equator in autumn with increased intensity. While CP-IOD has a maximum positive SSTA mainly in the central Indian Ocean south of the equator in summer and autumn which is distributed east-west belt-shaped with weaker intensity compared with EP-IOD. Further analysis shows that, positive SSTA in tropical northwestern Indian Ocean in summer may be primarily caused by weak southwest summer monsoon through a vertical entrainment mixing process during EP-IOD. In autumn, easterly wind anomalies, which lead to entrainment positive anomaly, play a key role in maintaining positive SSTA in tropical northwestern Indian Ocean. Positive SSTA in the middle-south of tropical Indian Ocean mainly results from a warm Rossby Wave. By comparison, the evolution of warming in the middle-south of tropical Indian Ocean during CP-IOD is mainly associated with strongly anomalous northwestern wind which weakens easterly monsoon in summer and autumn. Besides, the warm Rossby Wave excited by abnormal anticyclone over the tropical southeastern Indian Ocean really counts. |
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