Numerical reconstructions of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle
Numerical reconstructions of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle
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DOI：
10.5194/cp-3-15-2007
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发表时间：
2007-01-01
影响因子：
4.3
通讯作者：
Kageyama, M.
中科院分区：
文献类型：
--
作者：
Charbit, S.;Ritz, C.;Kageyama, M.
利用三维冰盖热力学模式模拟了末次冰期-间冰期旋回中北方冰盖的演变。冰盖模式是由六个不同的大气环流模式（AGCMs）的结果强迫。在研究期间的气候演变重建使用两个气候平衡模拟进行末次盛冰期（LGM）和现今的时期和插值通过这些快照之间的时间使用的冰川指数校准对GRIP三角洲O-18记录。由于它是由GRIP信号的定时驱动的，冰体积和冰覆盖面积的时间演变从一个模拟到另一个模拟大致相同。然而，冰体积曲线和冰盖的空间分布呈现出一些重大差异，从一个AGCM强迫到其他。这些差异的起源，这是最明显的冰量的最大幅度，分析气候强迫的差异。这种分析允许的能力的GCM模拟气候与过去的冰盖重建一致的部分评价。虽然有些模型正确地再现了某些特定地区冰盖的前进或后退，但没有一个模型能够完全符合观测到的海平面变化和地质数据，再现北美或欧亚的冰复合体。这些偏差可以归因于气候强迫和作为GCM运行边界条件的LGM冰盖重建中的缺点，但也要在冰盖模型本身缺少过程。
A 3-dimensional thermo-mechanical ice-sheet model is used to simulate the evolution of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle. The ice-sheet model is forced by the results from six different atmospheric general circulation models (AGCMs). The climate evolution over the period under study is reconstructed using two climate equilibrium simulations performed for the Last Glacial Maximum (LGM) and for the present-day periods and an interpolation through time between these snapshots using a glacial index calibrated against the GRIP delta O-18 record. Since it is driven by the timing of the GRIP signal, the temporal evolution of the ice volume and the ice-covered area is approximately the same from one simulation to the other. However, both ice volume curves and spatial distributions of the ice sheets present some major differences from one AGCM forcing to the other. The origin of these differences, which are most visible in the maximum amplitude of the ice volume, is analyzed in terms of differences in climate forcing. This analysis allows for a partial evaluation of the ability of GCMs to simulate climates consistent with the reconstructions of past ice sheets. Although some models properly reproduce the advance or retreat of ice sheets in some specific areas, none of them is able to reproduce both North American or Eurasian ice complexes in full agreement with observed sea-level variations and geological data. These deviations can be attributed to shortcomings in the climate forcing and in the LGM ice-sheet reconstruction used as a boundary condition for GCM runs, but also to missing processes in the ice-sheet model itself.