The influence of lateral Earth structure on inferences of global ice volume during the Last Glacial Maximum
The influence of lateral Earth structure on inferences of global ice volume during the Last Glacial Maximum
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DOI：
10.1016/j.quascirev.2022.107644
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发表时间：
2022-08
影响因子：
4
通讯作者：
L. Pan;G. Milne;K. Latychev;S. Goldberg;J. Austermann;M. Hoggard;J. Mitrovica
中科院分区：
文献类型：
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作者：
L. Pan;G. Milne;K. Latychev;S. Goldberg;J. Austermann;M. Hoggard;J. Mitrovica
远场相对海平面（RSL）记录与冰量或全球平均海平面（GMSL）变化之间的映射涉及冰川均衡调整（GIA）校正。因此，这种映射是敏感的GIA建模固有的不确定性，包括冰质量变化和粘弹性地球结构的时空历史。在这里，我们调查的影响，将地球结构的横向变化预测远场海平面，以确定这种来源的模型的不确定性显着影响全球冰量的估计在末次冰期最大（LGM）。我们考虑了一组40个3-D模拟，采样不同的地球模型参数：采用岩石圈厚度，地震速度模型用于推断横向温度变化，比例因子用于从温度到粘度的转换，以及球平均的“背景”粘度分布。此外，我们认为结果的基础上两个冰的历史。我们提出了这些模拟和一组1-D模拟在LGM之间的差异的全球地图，以及RSL的历史在5个地点，以前已被认为是在LGM冰量的估计：巴巴多斯，两个网站在大堡礁，波拿巴湾和巽他大陆架。我们发现，基于三维和一维地球模型的全球平均海平面（GMSL）在末次盛冰期的推断之间的差异在巴巴多斯达到峰值，差异范围为10.25至11米，平均值为10.6 -7米。在其他地点，差异范围从0.2米到-8米，平均差异在0.0米到-3米之间。比较不同的模拟对后，我们得出结论，在一般情况下，不同的地震模型，岩石圈厚度模型，背景1-D模型，从温度到粘度的比例因子的影响是显着的远场站点。最后，虽然我们没有找到一个一致的信号，在上述远场的网站，这将有助于调和的末次冰期的冰量估计从GIA研究和那些估计从总结区域冰盖重建，影响仍然是足够大的GIA分析RSL记录在远场的冰盖应包括3-D粘弹性地球模型。
The mapping between far-field relative sea level (RSL) records and changes in ice volume or global mean sea level (GMSL) involves a correction for glacial isostatic adjustment (GIA). This mapping is thus sensitive to uncertainties inherent to GIA modeling, including the spatio-temporal history of ice mass changes and viscoelastic Earth structure. Here, we investigate the effect of incorporating lateral variations in Earth structure on predicting far-field sea level in order to determine if this source of model uncertainty significantly impacts estimates of global ice volume at the Last Glacial Maximum (LGM). We consider a set of forty 3-D simulations that sample different Earth model parameters: the adopted lithospheric thickness, the seismic velocity model used to infer lateral temperature variations, the scaling factor used in the conversion from temperature to viscosity, and the spherically averaged “background” viscosity profile. In addition, we consider results based on two ice histories. We present global maps of the differences between these simulations and a set of 1-D simulations at the LGM, as well as RSL histories at 5 locations that have been previously considered in estimates of ice volume at LGM: Barbados, two sites at the Great Barrier Reef, Bonaparte Gulf and Sunda Shelf. We find that the difference between inferences of global mean sea level (GMSL) at LGM based on 3-D and 1-D Earth models peaks in Barbados with differences ranging from ∼2.5 to 11 m, with a mean of ∼6–7 m. At the other sites, the difference ranges from ∼2 to −8 m, with mean differences between ∼0 and −3 m. After comparing different pairs of simulations, we conclude that, in general, the impact of varying the seismic model, lithospheric thickness model, background 1-D model, and scaling factor from temperature to viscosity is significant at far-field sites. Finally, while we do not find a consistent signal at the above far-field sites that would help to reconcile the LGM ice volumes estimated from GIA studies and those estimated from summing regional ice sheet reconstructions, the impact is nonetheless large enough that GIA analyses of RSL records in the far field of ice sheets should include 3-D viscoelastic Earth models.