The Institut Pierre-Simon Laplace Climate Modeling Center has produced an ensemble of extended historical simulations using the IPSL-CM6A-LR climate model. This ensemble (referred to as IPSL-EHS) is composed of 32 members over the 1850–2059 period that share the same external forcings but differ in their initial conditions. In this study, we assess the simulated decadal to multidecadal climate variability in the IPSL-EHS. In particular, we examine the global temperature evolution and recent warming trends, and their consistency with ocean heat content and sea ice cover. The model exhibits a large low-frequency internal climate variability. In particular, a quasi-bicentennial mode of internal climate variability is present in the model and is associated with the Atlantic Meridional Overturning Circulation. Such variability modulates the global mean surface air temperature changes over the historical period by about 0.1K. This modulation is found to be linked to the phase present in the initial condition state of each member. This variability appears to decrease during the 1850–2018 period in response to external forcings. The analysis of the ocean heat content reveals furthermore an overestimation of the ocean stratification, which likely leads to an overestimation of the recent warming rate on average.

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IPSL-CM6A-LR 扩展历史模拟集合的介绍和评估

Institut Pierre-Simon Laplace 气候建模中心使用 IPSL-CM6A-LR 气候模型生成了一系列扩展历史模拟。该集合（称为 IPSL-EHS）由 1850 年至 2059 年期间的 32 个成员组成，这些成员共享相同的外强迫，但初始条件不同。在这项研究中，我们评估了 IPSL-EHS 中模拟的年代际到年代际气候变化。特别是，我们研究了全球温度演变和最近的变暖趋势，以及它们与海洋热含量和海冰覆盖的一致性。该模型表现出较大的低频内部气候变率。特别是，模型中存在准二百周年的内部气候变率模式，并且与大西洋经向翻转环流有关。0.1K。发现这种调制与每个成员的初始条件状态中存在的阶段有关。在 1850-2018 年期间，这种可变性似乎因外部强迫而减少。对海洋热含量的分析进一步揭示了对海洋分层的高估，这可能导致对近期平均变暖速率的高估。