Spinning up a highly complex, coupled Earth system model (ESM) is a time consuming and computationally demanding exercise. For models with interactive ice sheet components, this becomes a major challenge, as ice sheets are sensitive to bidirectional feedback processes and equilibrate over glacial timescales of up to many millennia. This work describes and demonstrates a computationally tractable, iterative procedure for spinning up a contemporary, highly complex ESM that includes an interactive ice sheet component. The procedure alternates between a computationally expensive coupled configuration and a computationally cheaper configuration where the atmospheric component is replaced by a data model. By periodically regenerating atmospheric forcing consistent with the coupled system, the data atmosphere remains adequately constrained to ensure that the broader model state evolves realistically. The applicability of the method is demonstrated by spinning up the preindustrial climate in the Community Earth System Model Version 2 (CESM2), coupled to the Community Ice Sheet Model Version 2 (CISM2) over Greenland. The equilibrium climate state is similar to the control climate from a coupled simulation with a prescribed Greenland ice sheet, indicating that the iterative procedure is consistent with a traditional spin‐up approach without interactive ice sheets. These results suggest that the iterative method presented here provides a faster and computationally cheaper method for spinning up a highly complex ESM, with or without interactive ice sheet components. The method described here has been used to develop the climate/ice sheet initial conditions for transient, ice sheet‐enabled simulations with CESM2‐CISM2 in the Coupled Model Intercomparison Project Phase 6 (CMIP6).

中文翻译：

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CESM2-CISM2的有效冰原/地球系统模型旋转程序：描述，评估和更广泛的适用性

建立高度复杂的耦合地球系统模型（ESM）是一项耗时且计算量大的工作。对于具有交互式冰盖组件的模型，这成为一个重大挑战，因为冰盖对双向反馈过程很敏感，并且在长达几千年的冰川时间尺度上保持平衡。这项工作描述并演示了一种可计算的，易于计算的迭代过程，用于分解包含交互冰盖组件的当代高度复杂的ESM。该过程在计算上昂贵的耦合配置和计算上便宜的配置之间交替，其中大气成分被数据模型代替。通过定期再生与耦合系统一致的大气强迫，数据气氛仍然受到足够的约束，以确保更广泛的模型状态切实可行地发展。该方法的适用性通过在格陵兰岛上的社区地球系统模型版本2（CESM2）中与工业冰原模型版本2（CISM2）结合起来改善了工业化前的气候而得到证明。平衡气候状态类似于带有指定格陵兰冰原的耦合模拟的控制气候，这表明迭代过程与没有交互式冰原的传统旋转方法一致。这些结果表明，本文介绍的迭代方法提供了一种更快且计算更便宜的方法，可以旋转高度复杂的ESM（带有或不带有交互式冰盖组件）。