A data-constrained large ensemble analysis of Antarctic evolution since the Eemian
A data-constrained large ensemble analysis of Antarctic evolution since the Eemian
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DOI：
10.1016/j.quascirev.2014.09.003
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发表时间：
2014-11-01
影响因子：
4
通讯作者：
Tarasov, Lev
中科院分区：
文献类型：
--
作者：
Briggs, Robert D.;Pollard, David;Tarasov, Lev
重建南极冰盖的历史行为对于理解和预测气候相互作用、冰盖敏感性和海平面贡献至关重要。此外，为了以任何置信度解释这种重建，需要有意义的不确定性估计。为了实现这一目标，本文介绍了在末次冰期循环中对南极演变进行的大集合数据约束研究的结果。冰盖年表是使用三维冰川系统模型生成的，该模型包括冰盖/溪流/陆架流;参数化的基底阻力系数;（考虑到次网格地形粗糙度、沉积可能性和系统模型与观测厚度的不匹配）;一个子网格接地线通量参数化;粘弹性基岩响应组件;参数化气候强迫;单独的货架和tidaling产犊治疗;和物理动机，经验得出，subshelf熔体组件。有31个集合参数来捕捉冰川循环气候，质量平衡过程和冰动力学的不确定性。一旦生成，使用一套观测数据（包括相对海平面，过去的冰厚度和接地线后退数据点的约束，以及现今的冰量和配置）和评估方法，为每次运行产生一个不适合的观测分数约束模型运行的集合。假设一个高斯误差模型的变体，分数被用来生成概率分布的过去的演变的冰盖。在我们的合奏为基础的分析南极冰量的末次冰期最大值（LGM）发生在类似的25-24 ka。末次盛冰期冰量相对于现今的过剩可能在5.6至14.3米当量海平面（mESL）之间，并且置信度较低，>10 mESL。从24 ka到17-16 ka，地面冰体积变化不大，此时开始广泛的冰消。罗斯海和威德尔海是冰量损失的最大来源。威德尔海部分的陆线主要撤退时期发生在10 ka之后，形成了现今的Ronne-Filchner陆架体系;罗斯海部分的陆线主要撤退阶段发生在12 ka之后。没有重大贡献（
Reconstructing the historical behaviour of the Antarctic Ice Sheet is essential for understanding and predicting climatic interactions, ice sheet sensitivities, and sea level contributions. Furthermore, to interpret such reconstructions with any degree of confidence, meaningful uncertainty estimates are required. Working toward this goal, this article presents results from a large-ensemble data-constrained study of Antarctic evolution over the Last Glacial cycle.Ice sheet chronologies have been generated using a 3-D glacial systems model that includes sheet/stream/shelf flow; a parametrized basal drag coefficient (accounting for sub-grid topographic roughness, sediment likelihood, and systematic model-to-observation thickness misfits); a sub-grid grounding-line flux parametrization; a visco-elastic bedrock response component; parametrized climate forcing; separate shelf and tidewater calving treatments; and a physically-motivated, empirically derived, subshelf melt component. There are 31 ensemble parameters to capture uncertainties in the glacial cycle climate, mass-balance processes, and ice dynamics. Once generated, the ensemble of model runs is constrained using a suite of observational data (including constraints on relative sea level, past ice thickness and grounding line retreat data-points, as well as present-day ice volumes and configuration) and an evaluation methodology that produces a misfit-to-observations score for each run. Assuming variants of a Gaussian error model, the scores are used to generate probability distributions for the past evolution of the ice sheet.In our ensemble-based analysis the Last Glacial Maximum (LGM) of Antarctic ice volume occurs at similar to 25-24 ka. The LGM ice volume excess relative to present-day is likely between 5.6 and 14.3 m equivalent sea level (mESL), and with less confidence >10 mESL. There is little change in the grounded ice volume from 24 ka until 17-16 ka at which time widespread deglaciation commences. The Ross and Weddell Sea sectors are the largest sources of ice mass loss. The major period of grounding line retreat in the Weddell Sea sector, resulting in the present-day Ronne-Filchner shelf system, occurs after 10 ka; the grounding line in the Ross Sea sector start its major retreat phase after 12 ka. There is no significant contribution (