摘要
热带印度洋偶极子(Indian Ocean dipole,IOD)和副热带南印度洋偶极子(subtropical Indian Ocean dipole,SIOD)作为热带和副热带印度洋海气耦合的主要模态,二者联系密切。本文基于梁氏-克里曼信息流理论确定IOD与SIOD互为因果,并利用Hadley中心的海表面温度数据以及NCEP大气再分析等数据分析了1950~2021年期间前期IOD对SIOD发展的影响及其年代际变化规律。结果显示,IOD超前SIOD的相关关系在1976年和2002年前后发生了年代际转变。1950~1976年期间(P1),二者关系不显著;1977~2002年期间(P2),二者存在显著负相关,当IOD超前SIOD 5个月时达到最大负相关,相关系数为-0.56;2003~2021年期间(P3),二者相关性有所减弱,相关系数为-0.33。IOD与SIOD主周期的变化进一步验证了二者相关关系的年代际变化。P2时期,IOD与SIOD之间存在显著的2~4 a反位相一致周期,而在P1、P3时期两者没有明显的同周期。与此同时,IOD超前SIOD时二者关系的年代际变化与太平洋年代际振荡(Pacific Decadal Oscillation,PDO)的位相转换有密切联系。PDO冷位相下,副热带印度洋大气环流响应较弱,海气背景不利于IOD对SIOD事件的激发。PDO暖位相能够通过ENSO加强赤道印度洋-太平洋的Walker环流异常,与赤道东风异常有关的反气旋环流促使热带西印度洋的正海表温度异常(sea surface temperature anomalies,SSTA)向东南方向延伸,促进东南印度洋正SSTA的发展;IOD通过经向环流的垂直运动引起中纬度对流层高层辐散,产生等效正压Rossby波,与之相关的低层异常气旋环流通过“风-蒸发-海表面温度”(wind-evaporation-SST,WES)反馈诱导副热带西南印度洋负SSTA的发展,二者共同促进了次年冬季负SIOD事件的生成。
The Indian Ocean dipole(IOD)and Subtropical Indian Ocean dipole(SIOD)are two dominate climatic modes in tropical and subtropical regions of Indian Ocean,respectively.Based on the Liang-Kleeman information flow method,it is suggested that IOD and SIOD have a causal relationship to each other.The changes in the relationship between preceding IOD and SIOD during 1950~2021 were analyzed using sea surface temperature data from the Hadley Centre and NCEP atmospheric reanalysis.It was found that there was a significant interdecadal change in the IOD-SIOD relationship around 1976 and 2002 when IOD led SIOD.The relationship was insignificant from 1950 to 1976(P1).During 1977~2002(P2),a significant negative correlation was observed between IOD and SIOD,with a maximum correlation coefficient of-0.56 when the former led the latter for 5 months.From 2003 onwards(P3),the correlation between the two dipoles became weak.The interdecadal variation of the periods for both IOD and SIOD may contribute to this change in their relationship.During P2,there was a similar period of 2~4 years between SIOD and IOD,whereas no significant resonance between them during P1 or P3.Furthermore,there was a close correlation between phase transition of PDO and interdecadal variation in IOD-SIOD relationship.During PDO's cold phase,atmospheric circulation response in subtropical Indian Ocean was weak,which was unfavorable for IOD triggering SIOD.On the contrary,during warm phase of PDO,the Walker circulation anomaly in the equatorial Indian-Pacific can be intensified via ENSO,leading to strengthened wind anomalies in the tropical eastern Indian Ocean.This contributes to the expansion of the western tropical Indian Ocean SSTA towards the southeastern Indian Ocean.Additionally,through the vertical motion of the meridional circulation,IOD can also elicit a stationary equivalent Rossby wave train.The associated anomalous cyclonic at low level induces negative SSTA in southwest Indian Ocean by wind-evaporation-SST feedback.Finally,negative SIOD reaches i
作者
时文娟
冯俊乔
王富军
王庆业
胡石建
张子叶
SHI Wen-Juan;FENG Jun-Qiao;WANG Fu-Jun;WANG Qing-Ye;HU Shi-Jian;ZHANG Zi-Ye(Shandong University of Science and Technology,Qingdao 266590,China;Key Laboratory of Ocean Circulation and Waves,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China;Key Laboratory of Ocean Observation and Forecasting,Chinese Academy of Sciences,Qingdao 266071,China)
出处
《海洋与湖沼》
CAS
CSCD
北大核心
2024年第4期802-816,共15页
Oceanologia Et Limnologia Sinica
基金
国家自然科学基金项目,42022040号,41976027号。
