| 摘要: |
| 为了增进对南印度洋副热带偶极子(Subtropical Indian Ocean Dipole, SIOD)年代际变化的认识, 基于Hadley中心的海表面温度(sea surface temperature, SST)、美国国家环境预报中心的大气再分析数据集Ⅰ(NCEP-NCAR Reanalysis1, NCEP)的大气再分析数据和欧洲中期天气预报中心的海洋再分析数据(Ocean Reanalysis System 4, ORAS4)等, 本文分析了1958~2020年SIOD年代际转变的特征和物理机制。结果显示, 2000年之前, SIOD存在2~4 a和4~6 a两个年际主周期, 但近20 a (2000~2020年)其年际变化周期以1.5~2.0 a为主。与此同时, SIOD的空间特征及其强度在1987年和2004年左右出现了两次显著的年代际转变: 1958~1986年(P1)期间强度最大, 1987~2003年(P2)期间最弱, 2004~2020年(P3)期间居中; P1期间SIOD的最大正SST异常(sea surface temperature anomalies, SSTA)中心位于(46°~80°E, 44°~28°S), P2期间向西南移动到(35°~65°E, 48°~34°S), 同时负SSTA中心较P1期间向南北方向延伸, P3期间正、负SSTA中心又回到P1时期的位置。相关分析结果表明, SIOD的年代际变化受南极涛动(Antarctic Oscillation, AAO)和厄尔尼诺-南方涛动(El Niño-Southern Oscillation, ENSO)的影响。P1期间, SIOD与AAO存在较强正相关。在研究时段, 除1982~1993年期间ENSO与SIOD的关系不显著外, 其他时段均呈显著负相关。海洋混合层热收支分析进一步研究发现, AAO与ENSO主要通过调制马斯克林高压(Mascarene high, MH)而影响海表面热通量(特别是潜热通量)的变化,进而影响SIOD。 |
| 关键词: 海表面温度 南印度洋副热带偶极子 年代际变化 |
| DOI：10.11693/hyhz20221200325 |
| 分类号:P732 |
| 基金项目:国家自然科学基金项目, 41976027号; 国家自然科学基金项目, 41730534号。 |
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| INTERDECADAL TRANSITION CHARACTERISTICS OF THE SUBTROPICAL INDIAN OCEAN DIPOLE |
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LIU Kai1,2, FENG Jun-Qiao2, LU Yun-Long2, DUAN Hua1
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1.Shandong University of Science and Technology, Qingdao 266590, China;2.Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
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| Abstract: |
| Using monthly mean observed SST data from the Hadley Centre, atmospheric reanalysis data from National Centers for Environmental (NCEP) and ocean reanalysis data from the European Centre for Medium Range Weather Forecasts (ORAS4), interdecadal characteristics and mechanism of the subtropical Indian Ocean dipole (SIOD) were investigated from 1958 to 2020. Results show that the SIOD is characterized by a mix of 2~4 years and 4~6 years of interannual timescale, but the period gradually shifts to a shorter period of about 1.5~2 years in the last 20 years (2000~2020). The spatial and intensity of SIOD exhibited two significant interdecadal shifts around 1987 and 2004 in addition to the above-mentioned interannual variability. Compared to 1987~2003 (P2), there was greater amplitude in 1958~1986 (P1) and 2004~2020 (P3). The center of the positive SSTA shifted from (46°~80°E, 44°~28°S) to (35°~65°E, 48°~34°S) and the negative center extended north and south relative to those in P1. Finally, the center returned back to the P1 position during P3. Correlation analysis showed that interdecadal variability of SIOD was influenced by the Antarctic Oscillation (AAO) and the El Niño-Southern Oscillation (ENSO). Prior to the mid-1980s, SIOD had a significant correlation with AAO. The relationship between ENSO and SIOD was significantly negative except for 1982~1993. In addition, the mixed heat budget demonstrated that AAO and ENSO influence changes in heat flux (especially latent heat flux) on the sea surface primarily by modulating Mascarene high (MH), thereby impacting SIOD. |
| Key words: sea surface temperature subtropical Indian Ocean Dipole interdecadal variability |
