气候变化领域集成服务门户(CCPortal): Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles

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DOI	10.5194/tc-11-2175-2017
	Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles
	Münch T.; Kipfstuhl S.; Freitag J.; Meyer H.; Laepple T.
发表日期	2017
ISSN	19940416
卷号	11 期号:5
英文摘要	The isotopic composition of water in ice sheets is extensively used to infer past climate changes. In low-accumulation regions their interpretation is, however, challenged by poorly constrained effects that may influence the initial isotope signal during and after deposition of the snow. This is reflected in snow-pit isotope data from Kohnen Station, Antarctica, which exhibit a seasonal cycle but also strong interannual variations that contradict local temperature observations. These inconsistencies persist even after averaging many profiles and are thus not explained by local stratigraphic noise. Previous studies have suggested that post-depositional processes may significantly influence the isotopic composition of East Antarctic firn. Here, we investigate the importance of post-depositional processes within the open-porous firn (≥10 cm depth) at Kohnen Station by separating spatial from temporal variability. To this end, we analyse 22 isotope profiles obtained from two snow trenches and examine the temporal isotope modifications by comparing the new data with published trench data extracted 2 years earlier. The initial isotope profiles undergo changes over time due to downward advection, firn diffusion and densification in magnitudes consistent with independent estimates. Beyond that, we find further modifications of the original isotope record to be unlikely or small in magnitude (<1%RMSD). These results show that the discrepancy between local temperatures and isotopes most likely originates from spatially coherent processes prior to or during deposition, such as precipitation intermittency or systematic isotope modifications acting on drifting or loose surface snow. © Author(s) 2017.
学科领域	annual variation; climate change; depositional environment; firn; ice sheet; isotopic composition; seasonal variation; snow accumulation; temperature effect; temporal variation; Antarctica; East Antarctica
语种	英语
scopus关键词	annual variation; climate change; depositional environment; firn; ice sheet; isotopic composition; seasonal variation; snow accumulation; temperature effect; temporal variation; Antarctica; East Antarctica
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/119333
作者单位	Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Telegrafenberg A43, Potsdam, 14473, Germany; Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, Potsdam, 14476, Germany; Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, Bremerhaven, 27568, Germany
推荐引用方式 GB/T 7714	Münch T.,Kipfstuhl S.,Freitag J.,et al. Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles[J],2017,11(5).
APA	Münch T.,Kipfstuhl S.,Freitag J.,Meyer H.,&Laepple T..(2017).Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles.Cryosphere,11(5).
MLA	Münch T.,et al."Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles".Cryosphere 11.5(2017).