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Effect of isostatic rebound on modelled ice volume variations during the last 200 kyr

机译:等静回弹对最近200年内模拟冰量变化的影响

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摘要

Deformation of the lithosphere under an ice load can be approximated using the hypothesis of local damped isostasy. This simple formulation has been systematically compared with a three-dimensional model of the crust-mantle system for simple ice-load scenarios with a period in the range 20-100 kyr. The comparison enables us to introduce the concepts of effective upper mantle density and effective relaxation time into the isostatic model for the response of the Earth to the ice sheets. These parameters depend on the Earth model considered, ice sheet size and the period of the load cycle. The local damped isostasy model has been implemented in the Louvain-la-Neuve climate model to assess the impact of isostasy on continental ice volume variations for the last 200 kyr. Results suggest that isostasy acts as a negative feedback for ice volume during the glaciation process and acts as a positive feedback during the deglaciation. Moreover, taking isostasy into account is necessary to simulate variations in Northern Hemisphere ice volume during isotopic stage 3. Lastly, the use of effective mantle density and effective relaxation time improves the model performance regarding SPECMAP reconstructions.
机译:冰负荷下岩石圈的变形可以使用局部阻尼等静量的假设来近似。该简单公式已与地幔系统的三维模型进行了系统比较,适用于周期为20至100年的简单冰荷载情景。通过比较,我们可以将有效上地幔密度和有效弛豫时间的概念引入等静压模型中,以实现地球对冰盖的响应。这些参数取决于所考虑的地球模型,冰盖尺寸和负荷周期。在Louvain-la-Neuve气候模型中已经实施了局部阻尼等静线模型,以评估等静线对过去200年内大陆冰量变化的影响。结果表明,在冰消融过程中,等静压是冰量的负反馈,而在冰消融过程中,等静量是正反馈。此外,必须要考虑等静点以模拟同位素阶段3中北半球冰量的变化。最后,有效地幔密度和有效弛豫时间的使用改善了SPECMAP重建的模型性能。

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