the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Archival of the water stable isotope signal in East Antarctic ice cores
Abstract. The oldest ice core records are obtained from the East Antarctic plateau. Water stable isotopes records are key for reconstructions of past climatic conditions both over the ice sheet and at the evaporation source. The accuracy of such climate reconstructions crucially depends on the knowledge of all the processes affecting the water vapour, precipitation and snow isotopic composition. Atmospheric fractionation processes are well understood and can be integrated in Rayleigh distillation and complex isotope enabled climate models. However, a comprehensive quantitative understanding of processes potentially altering the snow isotopic composition after the deposition is still missing, especially for exchanges between vapour and snow. In low accumulation sites such as found on the East Antarctic Plateau, these poorly constrained processes are especially likely to play a significant role. This limits the interpretation of isotopic composition from ice core records, specifically at short time scales.
Here, we combine observations of isotopic composition in the vapour, the precipitation, the surface snow and the buried snow from various sites of the East Antarctic Plateau. At the seasonal scale, we highlight a significant impact of metamorphism on surface snow isotopic signal compared to the initial precipitation isotopic signal. In particular, in summer, exchanges of water molecules between vapour and snow are driven by the sublimation/condensation cycles at the diurnal scale. Using highly resolved isotopic composition profiles from pits in five East Antarctic sites, we identify a common 20 cm cycle which cannot be attributed to the seasonal variability of precipitation. Altogether, the smaller range of isotopic compositions observed in the buried and in the surface snow compared to the precipitation, and also the reduced slope between surface snow isotopic composition and temperature compared to precipitation, constitute evidences of post-deposition processes affecting the variability of the isotopic composition in the snow pack. To reproduce these processes in snow-models is crucial to understand the link between snow isotopic composition and climatic conditions and to improve the interpretation of isotopic composition as a paleoclimate proxy.
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- RC1: 'comments on tc-2016-263', Anonymous Referee #1, 16 Dec 2016
- RC2: 'Interactive comment on “Archival of the water stable isotope signal in East Antarctic ice cores” by Mathieu Casado et al.', Anonymous Referee #2, 21 Dec 2016
- RC3: 'Accepted after minor revisions', Anonymous Referee #3, 02 Jan 2017
- AC1: 'Authors' response to the reviewers', Mathieu Casado, 25 Jan 2017
- RC1: 'comments on tc-2016-263', Anonymous Referee #1, 16 Dec 2016
- RC2: 'Interactive comment on “Archival of the water stable isotope signal in East Antarctic ice cores” by Mathieu Casado et al.', Anonymous Referee #2, 21 Dec 2016
- RC3: 'Accepted after minor revisions', Anonymous Referee #3, 02 Jan 2017
- AC1: 'Authors' response to the reviewers', Mathieu Casado, 25 Jan 2017
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Cited
8 citations as recorded by crossref.
- Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles T. Münch et al. 10.5194/tc-11-2175-2017
- Numerical experiments on vapor diffusion in polar snow and firn and its impact on isotopes using the multi-layer energy balance model Crocus in SURFEX v8.0 A. Touzeau et al. 10.5194/gmd-11-2393-2018
- The influence of the synoptic regime on stable water isotopes in precipitation at Dome C, East Antarctica E. Schlosser et al. 10.5194/tc-11-2345-2017
- Surface studies of water isotopes in Antarctica for quantitative interpretation of deep ice core data A. Landais et al. 10.1016/j.crte.2017.05.003
- Atmospheric moisture supersaturation in the near-surface atmosphere at Dome C, Antarctic Plateau C. Genthon et al. 10.5194/acp-17-691-2017
- Assessing the robustness of Antarctic temperature reconstructions over the past 2 millennia using pseudoproxy and data assimilation experiments F. Klein et al. 10.5194/cp-15-661-2019
- Stratigraphic noise and its potential drivers across the plateau of Dronning Maud Land, East Antarctica N. Hirsch et al. 10.5194/tc-17-4207-2023
- A stable isotope toolbox for water and inorganic carbon cycle studies C. Hillaire-Marcel et al. 10.1038/s43017-021-00209-0