DOI: 10.5194/cp-12-1061-2016
Scopus记录号: 2-s2.0-84966349274
论文题名: Local artifacts in ice core methane records caused by layered bubble trapping and in situ production: A multi-site investigation
作者: Rhodes R.H. ; Faïn X. ; Brook E.J. ; McConnell J.R. ; Maselli O.J. ; Sigl M. ; Edwards J. ; Buizert C. ; Blunier T. ; Chappellaz J. ; Freitag J.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2016
卷: 12, 期: 4 起始页码: 1061
结束页码: 1077
语种: 英语
Scopus关键词: accumulation
; amplitude
; artifact
; atmosphere
; atmospheric chemistry
; diffusion
; filter
; firn
; heterogeneous medium
; ice core
; ice sheet
; methane
; Arctic
; Greenland
英文摘要: Advances in trace gas analysis allow localised, non-atmospheric features to be resolved in ice cores, superimposed on the coherent atmospheric signal. These high-frequency signals could not have survived the low-pass filter effect that gas diffusion in the firn exerts on the atmospheric history and therefore do not result from changes in the atmospheric composition at the ice sheet surface. Using continuous methane (CH4) records obtained from five polar ice cores, we characterise these non-atmospheric signals and explore their origin. Isolated samples, enriched in CH4 in the Tunu13 (Greenland) record are linked to the presence of melt layers. Melting can enrich the methane concentration due to a solubility effect, but we find that an additional in situ process is required to generate the full magnitude of these anomalies. Furthermore, in all the ice cores studied there is evidence of reproducible, decimetre-scale CH4 variability. Through a series of tests, we demonstrate that this is an artifact of layered bubble trapping in a heterogeneous-density firn column; we use the term "trapping signal" for this phenomenon. The peak-to-peak amplitude of the trapping signal is typically 5 ppb, but may exceed 40 ppb. Signal magnitude increases with atmospheric CH4 growth rate and seasonal density contrast, and decreases with accumulation rate. Significant annual periodicity is present in the CH4 variability of two Greenland ice cores, suggesting that layered gas trapping at these sites is controlled by regular, seasonal variations in the physical properties of the firn. Future analytical campaigns should anticipate high-frequency artifacts at high-melt ice core sites or during time periods with high atmospheric CH4 growth rate in order to avoid misinterpretation of such features as past changes in atmospheric composition. © Author(s) 2016. 资助项目: AWI, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research
; CAS, Canadian Anesthesiologists' Society
; FWO, Fonds Wetenschappelijk Onderzoek
; KOPRI, Korea Polar Research Institute
; NERC, Natural Environment Research Council
; NRCan, Natural Resources Canada
; NSF, National Science Foundation
; NSF, National Science Foundation
; NSF, National Science Foundation
; NSF, National Science Foundation
; ANR, Agence Nationale de la Recherche
; ERC, European Research Council
; NWO, Nederlandse Organisatie voor Wetenschappelijk Onderzoek
; OPP, Office of Polar Programs
; OSU, Ohio State University Press
Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49021
Appears in Collections: 气候变化与战略
There are no files associated with this item.
Recommended Citation:
Rhodes R.H.,Faïn X.,Brook E.J.,et al. Local artifacts in ice core methane records caused by layered bubble trapping and in situ production: A multi-site investigation[J]. Climate of the Past,2016-01-01,12(4)