Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 5 5 2009 10.5194/cpd-5-2239-2009 http://www.clim-past-discuss.net/5/2239/2009/ http://www.clim-past-discuss.net/5/2239/2009/cpd-5-2239-2009.html http://www.clim-past-discuss.net/5/2239/2009/cpd-5-2239-2009.pdf 2239 2267 2009-10-08 Post-depositional changes in snow isotope content: preliminary results of laboratory experiments A. A. Ekaykin ekaykin@mail.ru T. Hondoh V. Y. Lipenkov A. Miyamoto Institute of Low Temperature Sciences, Hokkaido University, 060-0819 Sapporo, Japan Arctic and Antarctic Research Institute, 199397 St. Petersburg, Russia Isotopic content of the snow and firn thickness is assumed to be altered significantly due to the post-depositional (PD) mass- and isotope exchange with the atmospheric water vapor. If so, these effects should be accounted for in the ice core-based isotope-temperature paleo-reconstructions. In order to study the intensity of the PD processes we set up a series of laboratory experiments. In this paper we describe in detail the experimental technique and briefly overview preliminary results. It is shown that the PD modifications in the upper layer of snow thickness are noticeably strong even under such a low temperature as −35°C (the value typical for the Central Antarctic summer). It is demonstrated that the PD isotopic changes in snow can be approximated as a linear function of the relative mass loss due to snow sublimation. Possible applications for improving the isotope-temperature paleo-reconstructions are shortly discussed. Colbeck, S. C.: An overview of seasonal snow metamorphism, Rev. Geophys. Space Ge., 20, 45–61, 1982. Dansgaard, W., Johnsen, S., Clausen, H. B., and Gundestrup, N.: Stable isotope glaciology, Copenhagen, 1973. Dansgaard, W., Johnsen, S. J., Clausen, H. B., and Langway, C. 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