两类El Niño对应的印度洋偶极子事件的比较研究

钱景; 李崇银; 谭言科; 桂发银; 黎鑫

doi:10.16032/j.issn.1004-4965.2017.04.004

两类El Niño对应的印度洋偶极子事件的比较研究

doi: 10.16032/j.issn.1004-4965.2017.04.004

钱景¹,
李崇银^{1, 2},
谭言科^1, ,,
桂发银¹,
黎鑫¹

1.
解放军理工大学气象海洋学院，江苏南京 211101
2.
LASG国家重点实验室/中国科学院大气物理研究所，北京 100029

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

详细信息

通讯作者:
谭言科，男，重庆市人，副教授，从事季风热带海气相互作用研究。E-mail: yktan@sohu.com

中图分类号: P732
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- 被引次数: 0
出版历程
- 收稿日期: 2016-08-28
- 修回日期: 2017-09-19
- 刊出日期: 2017-08-01

COMPARING STUDY ON INDIAN OCEAN DIPOLE EVENTS ASSOCIATED WITH TWO TYPES OF EL NIÑO

Jing QIAN¹,
Chong-yin LI^{1, 2},
Yan-ke TAN^{1
, ,},
Fa-yin GUI¹,
Xin LI¹

1.
College of meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101, China
2.
LASG, Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029, China

摘要

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 Niño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 Niño而发生的IOD事件(EP-IOD)和伴随中部型El Niño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。
- 两类El Niño /
- 印度洋 /
- IOD /
- 季节演变 /
- 2.5层简化海洋模型
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 Niño 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 Niño (EP-IOD) and CP El Niño (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.
- two types of El Niño /
- Indian Ocean /
- IOD /
- seasonal evolution /
- 2.5 layer dynamic upper-ocean model

HTML全文

图 1 合成的EP-IOD事件发展年的夏季(a)和秋季(b)SSTA形势

单位：℃。图中仅显示通过0.10显著性检验的区域(阴影)，下文的合成图做相同处理。

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图 2 同图 1，但为合成的CP-IOD

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图 3 不同类型IOD事件发展年夏季(a，b)和秋季(c，d)1 000 hPa风场异常(矢量线，单位：m/s)及风速距平(阴影，单位：m/s)

a、c. EP-IOD事件；b、d. CP-IOD事件。

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图 4 合成的夏季(a，b)和秋季(c，d)海表高度距平分布

单位：10^-1 m。a、c. EP-IOD事件; b、d. CP-IOD事件。

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图 5 合成的夏秋两季区域(20 °S~10 °N)平均海表高度距平的时间-经度剖面

单位：10^-1 m。a. EP-IOD事件; b. CP-IOD事件。

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图 6 合成的夏季(a，b)和秋季(c，d)海表热通量异常的分布

单位：W/m²。a、c. EP-IOD事件; b，d. CP-IOD事件(向下为正)。

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图 7 GODAS 30 m以上平均(a)和简化模型模拟(b)的混合层流场(矢量线，单位：m/s)和温度场(阴影，单位：℃)的气候态(4个季节)分布特征，以及GODAS-IOD指数与模拟-IOD指数(MOD)的时间演变(c，单位：℃)

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图 8 2.5层模型中两类IOD事件在夏季和秋季的混合层热收支

a. EP-IOD事件热带西北印度洋；b. EP-IOD事件热带中南印度洋；c. CP-IOD事件热带中南印度洋。

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