气候变化领域集成服务门户(CCPortal): Diffusive equilibration of N2, O2 and CO2 mixing ratios in a 1.5-million-years-old ice core

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DOI	10.5194/tc-8-245-2014
	Diffusive equilibration of N2, O2 and CO2 mixing ratios in a 1.5-million-years-old ice core
	Bereiter B.; Fischer H.; Schwander J.; Stocker T.F.
发表日期	2014
ISSN	19940416
卷号	8 期号:1
英文摘要	In the framework of the International Partnerships in Ice Core Sciences, one of the most important targets is to retrieve an Antarctic ice core that extends over the last 1.5 million years (i.e. an ice core that enters the climate era when glacial-interglacial cycles followed the obliquity cycles of the earth). In such an ice core the annual layers of the oldest ice would be thinned by a factor of about 100 and the climatic information of a 10 000 yr interval would be contained in less than 1 m of ice. The gas record in such an Antarctic ice core can potentially reveal the role of greenhouse gas forcing on these 40 000 yr cycles. However, besides the extreme thinning of the annual layers, also the long residence time of the trapped air in the ice and the relatively high ice temperatures near the bedrock favour diffusive exchanges. To investigate the changes in the O2 / N2 ratio, as well as the trapped CO2 concentrations, we modelled the diffusive exchange of the trapped gases O2, N2 and CO2 along the vertical axis. However, the boundary conditions of a potential drilling site are not yet well constrained and the uncertainties in the permeation coefficients of the air constituents in the ice are large. In our simulations, we have set the drill site ice thickness at 2700 m and the bedrock ice temperature at 5-10 K below the ice pressure melting point. Using these conditions and including all further uncertainties associated with the drill site and the permeation coefficients, the results suggest that in the oldest ice the precessional variations in the O2 / N2 ratio will be damped by 50-100%, whereas CO2 concentration changes associated with glacial-interglacial variations will likely be conserved (simulated damping 5%). If the precessional O2 / N2 signal will have disappeared completely in this future ice core, orbital tuning of the ice-core age scale will be limited. © Author(s) 2014. CC Attribution 3.0 License.
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/120155
作者单位	Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland; Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
推荐引用方式 GB/T 7714	Bereiter B.,Fischer H.,Schwander J.,et al. Diffusive equilibration of N2, O2 and CO2 mixing ratios in a 1.5-million-years-old ice core[J],2014,8(1).
APA	Bereiter B.,Fischer H.,Schwander J.,&Stocker T.F..(2014).Diffusive equilibration of N2, O2 and CO2 mixing ratios in a 1.5-million-years-old ice core.Cryosphere,8(1).
MLA	Bereiter B.,et al."Diffusive equilibration of N2, O2 and CO2 mixing ratios in a 1.5-million-years-old ice core".Cryosphere 8.1(2014).