在古老的冰中,气候信号可能因预融和异常扩散而被取代
A W Rempel1, E D Waddington, J S Wettlaufer
1Applied Physics Laboratory, University of Washington, Box 355640, Seattle, Washington 98105, USA. awrempel@apl.washington.edu
Nature
|June 1, 2001
概括
冰芯的预融会导致杂质异常向更温暖的地区移动. 这种沉积后的迁移可以将气候信号分开50厘米,影响古气候重建.
科学领域:
- 古气候学 古气候学
- 冰川学的冰川学
- 材料科学 材料科学 材料科学
背景情况:
- 冰芯提供了跨越千年的高分辨率气候记录.
- 解释这些记录假定微量成分的沉积后迁移最小.
- 在未冷的谷物边界液体中发现的可溶性杂质是关键的气候代理物.
研究的目的:
- 调查预融对冰中的组成扩散的影响.
- 为了确定预化是否会导致杂质异常的显著空间分离.
- 评估这种现象对古气候重建的影响,特别是对于Eemian间冰川时期.
主要方法:
- 研究了多晶冰的相位行为,特别是预融化.
- 模拟了由预炼影响的组成扩散.
- 在类似于格陵兰岛Eemian间冰期冰的条件下模拟杂质运输.
主要成果:
- 预化驱动了杂质异常向温暖地区的转移.
- 这个过程在运输过程中保持了杂质异常的空间完整性.
- 在类似于Eemian的条件下,杂质波动可以从同一年龄的冰上移动多达50厘米.
结论:
- 融化前诱导的组成扩散显著影响冰芯代理解释.
- 杂质的空间分离挑战了冰芯气候信号的直接年龄测定.
- 这种机制可能解释了古气候记录中的差异,例如有关Eemian冷却事件的差异.
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