Interannual to Decadal Variability of Tropical Indian Ocean Sea Surface Temperature: Pacific Influence versus Local Internal Variability
Interannual to Decadal Variability of Tropical Indian Ocean Sea Surface Temperature: Pacific Influence versus Local Internal Variability
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DOI：
10.1175/jcli-d-20-0807.1
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发表时间：
2021-04
影响因子：
4.9
通讯作者：
Lei Zhang;Gang Wang;M. Newman;W. Han
中科院分区：
文献类型：
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作者：
Lei Zhang;Gang Wang;M. Newman;W. Han
印度洋因其对区域和全球气候的重大影响而受到越来越多的关注。然而，由印度洋内部过程引起的海表温度（SST）变化，特别是在年代际及更长时间尺度上，尚未得到很好的理解，而且来自热带太平洋的外部影响也未被量化。本文通过观测分析了热带印度洋年际到年代际的海表温度变化，并利用线性逆模型（LIM）探讨了来自太平洋的外部影响与印度洋内部过程的作用。在LIM动力算子以及驱动系统的不可预测的随机噪声中，都对印度洋和热带太平洋海表温度异常（SSTA）之间的耦合进行了评估。结果表明，观测到的印度洋全盆（IOB）范围的海表温度异常模式在很大程度上是对太平洋厄尔尼诺 - 南方涛动（ENSO）强迫的响应，尽管它反过来对ENSO有阻尼作用，特别是在年际和年代际时间尺度上。另一方面，印度洋偶极子（IOD）是一种印度洋内部模态，它能积极影响ENSO；ENSO对IOD也有反馈作用，但在年代际时间尺度上相当微弱。第三种模态部分与副热带印度洋偶极子（SIOD）有关，它主要由印度洋内部过程产生，尽管其中一小部分与ENSO耦合。总体而言，印度洋内部产生的海表温度变化幅度与ENSO强迫产生的幅度相当，而且印度洋往往会积极影响热带太平洋。这些结果表明，印度洋 - 太平洋相互作用是一个双向过程。
The Indian Ocean has received increasing attention for its large impacts on regional and global climate. However, sea surface temperature (SST) variability arising from Indian Ocean internal processes has not been well understood particularly on decadal and longer time scales, and the external influence from the tropical Pacific has not been quantified. This paper analyzes the interannual-to-decadal SST variability in the tropical Indian Ocean in observations and explores the external influence from the Pacific versus internal processes within the Indian Ocean using a linear inverse model (LIM). Coupling between Indian Ocean and tropical Pacific SST anomalies (SSTAs) is assessed both within the LIM dynamical operator and the unpredictable stochastic noise that forces the system. Results show that the observed Indian Ocean basin (IOB)-wide SSTA pattern is largely a response to the Pacific ENSO forcing, although it in turn has a damping effect on ENSO especially on annual and decadal time scales. On the other hand, the Indian Ocean dipole (IOD) is an Indian Ocean internal mode that can actively affect ENSO; ENSO also has a returning effect on the IOD, which is rather weak on decadal time scale. The third mode is partly associated with the subtropical Indian Ocean dipole (SIOD), and it is primarily generated by Indian Ocean internal processes, although a small component of it is coupled with ENSO. Overall, the amplitude of Indian Ocean internally generated SST variability is comparable to that forced by ENSO, and the Indian Ocean tends to actively influence the tropical Pacific. These results suggest that the Indian–Pacific Ocean interaction is a two-way process.