Exploring the role of snow metamorphism on the isotopic composition of the surface snow at EastGRIP

• Published in: The Cryosphere
• Main Authors: Stuart, Romilly Harris, Faber, Anne Katrine, Wahl, Sonja, Hörhold, Maria W., Kipfstuhl, Sepp, Vasskog, Kristian, Behrens, Melanie, Zuhr, Alexandra M., Steen-Larsen, Hans Christian
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chinese Academy of Sciences and Beijing Normal University; Helmholtz Centre for Polar and Marine Research; National Institute of Polar Research and Arctic Challenge for Sustainability; SNOWISO; National Science Foundation, NSF; Office of Polar Programs, OPP; Horizon 2020 Framework Programme, H2020, (759526); H2020 European Research Council, ERC; European Research Council, ERC; Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF; Københavns Universitet, KU; Institut Polaire Français Paul Emile Victor, IPEV; A.P. Møller og Hustru Chastine Mc-Kinney Møllers Fond til almene Formaal; Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, AWI
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDU]Sciences of the Universe [physics]; Greenland; East Greenland; East Greenland Ice-core Project; Greenland ice core; Greenland Ice core Project; ice core; The Cryosphere
• Online Access: https://hal.science/hal-04195108; https://hal.science/hal-04195108/document; https://hal.science/hal-04195108/file/tc-17-1185-2023.pdf; https://doi.org/10.5194/tc-17-1185-2023

International audience Stable water isotopes from polar ice cores are invaluable high-resolution climate proxy records. Recent studies have aimed to improve our understanding of how the climate signal is stored in the stable water isotope record by addressing the influence of post-depositional processes on the isotopic composition of surface snow. In this study, the relationship between surface snow metamorphism and water isotopes during precipitation-free periods is explored using measurements of snow-specific surface area (SSA). Continuous daily SSA measurements from the East Greenland Ice Core Project site (EastGRIP) during the summer seasons of 2017, 2018 and 2019 are used to develop an empirical decay model to describe events of rapid decrease in SSA linked to snow metamorphism. We find that SSA decay during precipitation-free periods at the EastGRIP site is best described by the exponential equation SSA(t)Combining double low line(SSA0-22).e-αt+22, and has a dependency on wind speed. The relationship between surface snow SSA and snow isotopic composition is primarily explored using empirical orthogonal function analysis. A coherence between SSA and deuterium excess is apparent during 2017 and 2019, suggesting that processes driving change in SSA also influence snow deuterium excess. By contrast, 2018 was characterised by a covariance between SSA and 18O highlighting the inter-Annual variability in surface regimes. Moreover, we observed changes in isotopic composition consistent with fractionation effects associated with sublimation and vapour diffusion during periods of rapid decrease in SSA. Our findings support recent studies which provide evidence of isotopic fractionation during sublimation, and show that snow deuterium excess is modified during snow metamorphism.