Impacts of the PMIP4 ice sheets on Northern Hemisphere climate during the last glacial period
Impacts of the PMIP4 ice sheets on Northern Hemisphere climate during the last glacial period
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DOI：
10.1007/s00382-022-06456-1
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发表时间：
2020-03
期刊：
影响因子：
4.6
通讯作者：
K. Izumi;P. Valdes;R. Ivanović;L. Gregoire
中科院分区：
文献类型：
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作者：
K. Izumi;P. Valdes;R. Ivanović;L. Gregoire
本研究使用大气-海洋-植被耦合模型 HadCM3B-M2.1aD 全面调查了末次盛冰期 (LGM) 气候的平均状态，特别是与不同古气候模拟比对项目第 4 阶段 (PMIP4) 冰盖、ICE-6G_C、GLAC-1D 和 PMIP3 相关的北半球大气环流的影响。 PMIP3 冰盖的模拟比两个 PMIP4 冰盖的模拟都要冷，主要是因为影响表面反照率的陆地冰面积更大。然而，环流的变化影响海冰覆盖，导致 GLAC-1D 模拟几乎同样寒冷。尽管PMIP4冰盖也在大气环流中引起不同的响应，但在所有模拟中都发现了一些共同特征，包括冬季上层北大西洋急流的加强和横向扩展，伴有较大的西南-东北倾斜和夏季北太平洋急流，冬季冰岛低压和亚速尔高压以及夏季太平洋高压的南移。与陆地-海洋重建相比，所有 PMIP4 冰盖实验都高估了末次冰川冷却和潮湿条件。 ICE-6G_C冰盖的模拟提供了最接近的LGM气候再现，而PMIP3冰盖的模拟则显示了最冷的LGM气候状态。我们的研究表明，为了“基准”气候模型真实模拟末次盛冰期气候的能力，我们需要有可靠的边界条件，以确保任何模型偏差都是由模型限制引起的，而不是由末次盛冰期边界条件的不确定性引起的。
This study comprehensively investigates the impacts on the mean state of the Last Glacial Maximum (LGM) climate, particularly atmospheric circulation over the Northern Hemisphere associated with the different Paleoclimate Modelling Intercomparison Project Phase 4 (PMIP4) ice sheets, ICE-6G_C, GLAC-1D, and PMIP3, using the coupled atmosphere–ocean–vegetation model HadCM3B-M2.1aD. The simulation with PMIP3 ice sheets is colder than either of the two PMIP4 ice sheets mainly because of the larger area of land ice impacting surface albedo. However, changes in the circulation impact sea ice cover resulting in the GLAC-1D simulation being almost as cold. Although the PMIP4 ice sheets also induce different responses in the atmospheric circulation, some common features are identified in all simulations, including strengthening and lateral expansion of the winter upper-level North Atlantic jet with a large southwest-northeast tilt and summertime North Pacific jet, a southward shift of the wintertime Icelandic Low and Azores High and the summertime Pacific High. Compared to terrestrial-ocean reconstructions, all the PMIP4 ice sheet experiments overestimate the LGM cooling and wet conditions. The simulation with the ICE-6G_C ice sheet provides the closest reproduction of LGM climate, while the simulation with the PMIP3 ice sheet shows the coldest LGM climate state. Our study shows that in order to "benchmark" the ability of climate models to realistically simulate the LGM climate, we need to have reliable boundary conditions to ensure that any model biases are caused by model limitations rather than uncertainty about the LGM boundary conditions.