Data for manuscript "Modes of Variability in E3SM and CESM Large Ensembles"

An adequate characterization of internal modes of climate variability (MoV) is prerequisite for both accurate seasonal predictions and the attribution and detection of forced climate change in nature. Assessing the fidelity of climate models in simulating MoV is therefore essential; however, doing so is complicated by the large intrinsic variations in MoV and the limited span of the observational record. Large ensembles (LEs) provide a unique opportunity to assess model fidelity in simulating MoV and quantify inter-model contrasts. In this work, these goals are pursued in four recently produced LEs: the Energy Exascale Earth System Model (E3SM) versions 1 and 2 LEs, and the Community Earth System Model (CESM) versions 1 and 2 LEs. In general, the representation of MoV is found to improve across successive E3SM and CESM versions concurrent with improved simulation of the base state climate. The patterns of global coupled modes and many extratropical modes are well simulated by both E3SM2 and CESM2, though various persistent shortcomings are identified. The results both demonstrate the successes of these recent model versions and suggest the potential for continued improvement in the representation of MoV with advances in model physics.

对气候变率（MoV）内部模式的充分表征是准确进行季节性预测以及自然界中气候变化归因与检测的先决条件。因此，评估气候模型在模拟MoV方面的准确性至关重要；然而，这一过程因MoV的内在变率较大以及观测记录的有限跨度而变得复杂。大型集合（LEs）为评估模型在模拟MoV方面的准确性以及量化模型间差异提供了独特的机会。在本研究中，上述目标在四个近期生成的LEs中得以追求：能源埃克萨级地球系统模型（E3SM）的版本1和2 LEs，以及社区地球系统模型（CESM）的版本1和2 LEs。总体而言，MoV的表征在E3SM和CESM的连续版本中得到了提升，这与基本状态气候模拟的改善相一致。全球耦合模式的模式和许多副热带模式的模式由E3SM2和CESM2均得到了良好的模拟，尽管仍存在各种持续的不足。这些结果不仅展示了这些最新模型版本的成就，而且预示着随着模型物理学的进步，MoV表征的持续改进潜力。