Indian Ocean variability changes in the Paleoclimate Modelling Intercomparison Project
Indian Ocean variability changes in the Paleoclimate Modelling Intercomparison Project
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DOI：
10.5194/cp-19-681-2023
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发表时间：
2023-03
影响因子：
4.3
通讯作者：
C. Brierley;K. Thirumalai;Edward Grindrod;J. Barnsley
中科院分区：
文献类型：
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作者：
C. Brierley;K. Thirumalai;Edward Grindrod;J. Barnsley
抽象。印度洋呈现出多种年际气候变化模式，其未来的行为是不确定的。最近对冰川气候的分析发现，印度洋还有一种类似厄尔尼诺的赤道模式，这种模式也可能在未来的温暖状态中出现。在这里，我们探讨了在热带印度洋模拟的古气候模式相互比较项目（PMIP 4）的变化。这些模拟是由一组模型进行的，这些模型有助于耦合模型相互比较项目6和四个协调的实验：三个过去的时期-全新世中期（6000年前），末次冰期最大期（21000年前），末次间冰期（127000年前）-和一个理想化的强迫情景，以检查温室效应的影响。这两个间冰期实验用于描述轨道变化在季节循环中的作用，而另一对实验则侧重于对全球温度大幅变化的反应。印度洋海盆模态（IOBM）在全新世中期和末次间冰期都是衰减的，其衰减量与太平洋厄尔尼诺-南方涛动的衰减有关。IOBM的强度没有随着全球温度的变化而发生一致的变化;印度洋偶极子（IOD）和类厄尔尼诺模式的变化也没有。在轨道强迫下，IOD在全新世中期的实验中强烈减弱，在最后一次间冰期的振幅只有轻微的减少。轨道变化确实影响印度洋偶极子的SST模式，冷极到达赤道并沿着延伸。区域季节性的诱导变化被假设为是印度洋变率变化的重要控制因素。
Abstract. The Indian Ocean exhibits multiple modes of interannual climate variability, whose future behaviour is uncertain. Recent analysis of glacial climates has uncovered an additional El Niño-like equatorial mode in the Indian Ocean, which could also emerge in future warm states. Here we explore changes in the tropical Indian Ocean simulated by the Paleoclimate Model Intercomparison Project (PMIP4). These simulations are performed by an ensemble of models contributing to the Coupled Model Intercomparison Project 6 and over four coordinated experiments: three past periods – the mid-Holocene (6000 years ago), the Last Glacial Maximum (21 000 years ago), the last interglacial (127 000 years ago) – and an idealized forcing scenario to examine the impact of greenhouse forcing. The two interglacial experiments are used to characterize the role of orbital variations in the seasonal cycle, whilst the other pair focus on responses to large changes in global temperature. The Indian Ocean Basin Mode (IOBM) is damped in both the mid-Holocene and last interglacial, with the amount related to the damping of the El Niño–Southern Oscillation in the Pacific. No coherent changes in the strength of the IOBM are seen with global temperature changes; neither are changes in the Indian Ocean Dipole (IOD) nor the Niño-like mode. Under orbital forcing, the IOD robustly weakens during the mid-Holocene experiment, with only minor reductions in amplitude during the last interglacial. Orbital changes do impact the SST pattern of the Indian Ocean Dipole, with the cold pole reaching up to the Equator and extending along it. Induced changes in the regional seasonality are hypothesized to be an important control on changes in the Indian Ocean variability.