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Climate reconstruction from ice cores rely on good knowledge of equilibrium and kinetic isotopic fractionation at each step of the water cycle. One of the strongest limitations when interpreting water isotopes in remote Antarctic ice cores is the formulation of the isotopic fractionation at solid condensation (vapour to ice). The uncertainties associated with the coefficients for equilibrium fractionation and water vapour diffusion in air make the formulation of isotopic fractionation at solid condensation only empirical.Here, using (1) recent development in the measurements of water isotopes in the water vapour through infra-red spectroscopy and (2) the possibility to measure accurately 17O-excess of water, we test the classical formulation and parameterization of isotopic fractionation at solid condensation. The spatial variability of water vapour isotopic composition differs from classical formulation from Jouzel and Merlivat (1984, figure b) but can be relatively well reproduced by the resolution of diffusion toward a cold plate. In addition, our experiments highlight the impact of kinetic fractionation at condensation on 17O-excess for the first time. This preliminary study opens new perspectives to revisit the classical formulation of water isotopic fractionation during solid condensation at very low temperature.&#160;[caption id="attachment_413" align="alignnone" width="300"] a) Schematic of the processes involved in isotopic fractionation at solid condensation: a boundary layer of only a few millimetres where vapour is at equilibrium with the ice is formed, further away, diffusion prevails.[/caption][caption id="attachment_443" align="alignnone" width="300"] b) Measurement of the vapour (full circles), ice (empty squares), and vapour at equilibrium with the ice (empty circles) isotopic composition during two cloud chamber experiments (low and high supersaturation).[/caption]Mathieu Casado, Alexandre Cauquoin, Amaelle Landais, Dan Israel, Anaïs Orsi, Edouard Pangui, Janek Landsberg, Erik Kerstel, Frederic Prie, Jean-François DoussinLien vers l’article : http://dx.doi.org/10.1016/j.gca.2015.11.009Poster AGU : Lundi 14 décembre 2015, 14h00 – 18h00 Moscone south Poster hall.Remerciements : European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement n°30604, ANR Citronnier et le CNRS-INSU pour soutenir l’instrument national CESAM. Recherche menée conjointement entre le LSCE (IPSL, Gif sur Yvette), le LISA (IPSL, Créteil) et le LIPHY (CNRS – UJF, Grenoble). 