大气科学2017，Vol.41Issue(5)：975-987,13.DOI:10.3878/j.issn.1006-9895.1701.16225
印度洋冬季风异常海气环流耦合模态分析
Analysis of Abnormal Air-Sea Coupled Mode and the Indian Winter Monsoon
摘要
Abstract
This paper analyzes and discusses the abnormal air-sea coupled mode and the Indian winter monsoon.Main conclusions are as follows.In the first leading mode,sea surface and low level atmospheric circulation anomalies mainly occur over the eastern India Ocean,while upper ocean circulation anomalies,which embody in the westward equatorial warm current and eastward equatorial counter current,mainly reflect the winter monsoon circulation anomaly over the India Ocean.In the second leading mode,atmospheric circulation anomalies mainly occur over the Bay of Bengal,the Arabian Sea and the equatorial India Ocean;the upper ocean circulation anomalies are similar to that in the first leading mode,except that they also embody the abnormal Somali warm current.The first and second leading modes correspond to east and west modes of the Indian winter monsoon,which are also the primary and secondary modes of the Indian winter monsoon.The period of their inter-annual variation is about 4 years.The main periods of their inter-decadal variation are about 18 and 22 years respectively.The primary and secondary modes underwent mutation in 1976,and 1976 and 1978 respectively.The Indian winter monsoon has a 4-year period of inter-annual variation and underwent an obvious mutation in 1976.The inter-decadal variations of the primary and secondary modes correspond to those of the second and first modes of the winter North Pacific air-sea combination revealed by the Complex EOF (CEOF),which reflects the close relationship of the two oceans.This is because the Mongolia-Siberian high is a common source of the South Asian and the East Asian winter monsoon,and has significant influences on atmospheric circulation anomalies over the two oceans.The South Asian winter monsoon is stronger when the Hadley circulation over the Indian Ocean and convection on the equatorial convergence belt are stronger,and vice versa.The primary and secondary modes of the winter monsoon have the similar situation.In addition,this reflects the coupling relationship between anomalies of the South Asian winter monsoon circulation and tropical circulation in the winter.When the primary and secondary modes turn to positive or negative,SST anomalies of the near-surface tropical Indian Ocean demonstrate a north-south seesaw pattern and a west-east seasaw pattern,and the former is the primary one.The Indian winter monsoon prohibits the formation of the Indian dipole,and this explains why this dipole is the weakest in the winter.In the tropical Indian Ocean,the areas of atmospheric descending and ascending motions in low levels correspond to the areas of ocean descending and ascending motions near the sea surface,which constitutes the negative feedback mechanism for the air-sea interaction.In addition,it contributes to maintenance and stability of the South Asian winter monsoon,the Hadley circulation,the equatorial convergence belt and the Indian winter monsoon circulation.关键词
印度洋/冬季风异常/海气环流耦合/复EOF分解Key words
Indian Ocean/Abnormal winter monsoon/Air-sea coupled circulation/Complex EOF decomposition分类
天文与地球科学引用本文复制引用
张东凌,卢姁,张铭..印度洋冬季风异常海气环流耦合模态分析[J].大气科学,2017,41(5):975-987,13.基金项目
国家重点基础研究发展计划(973计划)项目 2013CB956203 （973计划）
National Basic Research Program of China (973 Program) (Grant 2013CB956203) （973 Program）
