Impact of precipitation seasonality changes on isotopic signals in polar ice cores: a multi-model analysis
Impact of precipitation seasonality changes on isotopic signals in polar ice cores: a multi-model analysis
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DOI：
10.1016/s0012-821x(03)00550-8
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发表时间：
2003-12
影响因子：
5.3
通讯作者：
G. Krinner;M. Werner
中科院分区：
文献类型：
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作者：
G. Krinner;M. Werner
对于格陵兰中部，水同位素分析表明，自末次盛冰期以来，温度差约为10°C。然而，钻孔温度测量和气体扩散温度测量表明，LGM的表面温度比今天低约20°C。两个大气环流模型研究表明，格陵兰中部季节性降水时间的变化可能导致了LGM水同位素代用温度的暖偏差，这种偏差可以解释估计的古温度的差异。在这里，我们提出了一个分析的大气环流模型模拟的古气候建模比较项目的框架内完成的。这些模型表明，在末次冰期格陵兰中部的降水和表面质量平衡的季节性周期可能与今天有很大的不同。这支持了这样的想法，即在格陵兰岛的LGM水同位素测温的准确性可能会受到损害，作为一个修改的表面质量平衡的季节性的结果。然而，模型不同意的幅度和符号的偏见。对于中东部南极洲，一个强大的季节性效应的LGM同位素信号没有模拟任何分析模型。对于全新世中期（6kyr BP）的模型表明，相对较弱的同位素古温度计的偏见与两个冰盖的表面质量平衡的季节性变化。
For Central Greenland, water isotope analysis indicates a temperature difference of about 10°C since the Last Glacial Maximum (LGM). However, borehole thermometry and gas diffusion thermometry indicate that LGM surface temperatures were about 20°C colder than today. Two general circulation model studies have shown that changes in the seasonal precipitation timing in Central Greenland might have caused a warm bias in the LGM water isotope proxy temperatures, and that this bias could explain the difference in the estimated paleotemperatures. Here we present an analysis of a number of atmospheric general circulation model simulations mostly done within the framework of the Paleoclimate Modeling Intercomparison Project. The models suggest that the seasonal cycle of precipitation and surface mass balance over Central Greenland at the LGM might have been very different from today. This supports the idea that the accuracy of the water isotope thermometry at the LGM in Greenland might be compromised as a result of a modified surface mass balance seasonality. However, the models disagree on the amplitude and sign of the bias. For Central East Antarctica, a strong seasonality effect on the LGM isotopic signal is not simulated by any of the analyzed models. For the mid-Holocene (6 kyr BP) the models suggest relatively weak isotope paleothermometry biases linked to changes in the surface mass balance seasonality over both ice sheets.