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Article Dans Une Revue Geophysical Research Letters Année : 2021

Water Isotopic Signature of Surface Snow Metamorphism in Antarctica

Résumé

In low accumulation regions of Antarctica, precipitation is so sparse that the processes occurring after snowfall (post-deposition), such as surface metamorphism (Picard et al., 2012), sublimation and solid condensation (Genthon et al., 2017), as well as the redistribution of snow by wind (Groot Zwaaftink et al., 2013; Picard et al., 2019), play a prominent role in how snow accumulates to build the snowpack. These processes strongly affect the physical properties (albedo, density, and grain size) and geochemical composition of snow. For instance, snow grain size, which controls the albedo (Grenfell et al., 1994; Wiscombe & Warren, 1980), is the result of the competition between precipitation which brings small size grains on the surface and metamorphism which coarsens existing grains (Picard et al., 2012). These post-deposition processes influence the snow isotopic composition (δ 18 O or δD for the first order) that are traditionally interpreted as proxies of past temperatures in ice cores. Before deposition, the link between temperature and δ 18 O is due to the Rayleigh distillation of moist air from evaporation sites at low latitudes to the high-latitude precipitation sites (Dansgaard, 1964): When temperature decreases and precipitation occurs, the condensed phase becomes enriched and the remaining moisture depleted of heavy isotopes. In Antarctica, ice cores covering several glacial-interglacial transitions have been retrieved from sites that combine two assets: large ice thickness and low accumulation (EPICA, 2004; Kawamura et al., 2017; Petit et al., 1999). However, the low accumulation lead to the contributions from poorly
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Dates et versions

hal-03348483 , version 1 (19-09-2021)

Identifiants

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Mathieu Casado, Amaelle Landais, Ghislain Picard, Laurent Arnaud, Giuliano Dreossi, et al.. Water Isotopic Signature of Surface Snow Metamorphism in Antarctica. Geophysical Research Letters, 2021, 48 (17), ⟨10.1029/2021gl093382⟩. ⟨hal-03348483⟩
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