DOI: 10.5194/tc-11-2175-2017
Scopus记录号: 2-s2.0-85029291118
论文题名: Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles
作者: Münch T ; , Kipfstuhl S ; , Freitag J ; , Meyer H ; , Laepple T
刊名: Cryosphere
ISSN: 19940416
出版年: 2017
卷: 11, 期: 5 起始页码: 2175
结束页码: 2188
语种: 英语
英文关键词: annual variation
; climate change
; depositional environment
; firn
; ice sheet
; isotopic composition
; seasonal variation
; snow accumulation
; temperature effect
; temporal variation
; Antarctica
; East Antarctica
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/75502
Appears in Collections: 影响、适应和脆弱性 气候变化与战略
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作者单位: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Telegrafenberg A43, Potsdam, Germany; Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, Potsdam, Germany; Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, Bremerhaven, Germany
Recommended Citation:
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]. Cryosphere,2017-01-01,11(5)