Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters

• Published in: The Cryosphere
• Main Authors: Touzeau, Alexandra, Landais, Amaëlle, Uemura, Ryu, Fukui, Kotaro, Fujita, Shuji, Guilbaud, Sarah, Ekaykin, Alexey, Casado, Mathieu, Barkan, Eugeni, Luz, Boaz, Magand, Olivier, Teste, Grégory, Meur, Emmanuel Le, Baroni, Mélanie, Savarino, Joël, Bourgeois, Ilann, Risi, Camille, STENNI, Barbara
• Other Authors: Stenni, Barbara
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2016
• Subjects: GENERAL-CIRCULATION MODEL; GLACIAL-INTERGLACIAL CHANGES; DEUTERIUM EXCESS SIGNAL; WATER-STABLE ISOTOPES; GREENLAND ICE CORES; DRONNING MAUD LAND; ACCUMULATION RATE; VOSTOK STATION; DOME-C; TEMPORAL VARIABILITY; Settore GEO/08 - Geochimica e Vulcanologia; East Antarctica; Dronning Maud Land; Greenland; Vostok Station; Antarc*; Antarctica; Greenland ice cores
• Online Access: http://hdl.handle.net/10278/3673405; https://doi.org/10.5194/tc-10-837-2016

The isotopic compositions of oxygen and hydrogen in ice cores are invaluable tools for the reconstruction of past climate variations. Used alone, they give insights into the variations of the local temperature, whereas taken together they can provide information on the climatic conditions at the point of origin of the moisture. However, recent analyses of snow from shallow pits indicate that the climatic signal can become erased in very low accumulation regions, due to local processes of snow reworking. The signal-to-noise ratio decreases and the climatic signal can then only be retrieved using stacks of several snow pits. Obviously, the signal is not completely lost at this stage, otherwise it would be impossible to extract valuable climate information from ice cores as has been done, for instance, for the last glaciation. To better understand how the climatic signal is passed from the precipitation to the snow, we present here results from varied snow samples from East Antarctica. First, we look at the relationship between isotopes and temperature from a geographical point of view, using results from three traverses across Antarctica, to see how the relationship is built up through the distillation process. We also take advantage of these measures to see how second-order parameters (d-excess and O-17-excess) are related to delta O-18 and how they are controlled. d-excess increases in the interior of the continent (i.e., when delta O-18 decreases), due to the distillation process, whereas O-17-excess decreases in remote areas, due to kinetic fractionation at low temperature. In both cases, these changes are associated with the loss of original information regarding the source. Then, we look at the same relationships in precipitation samples collected over 1 year at Dome C and Vostok, as well as in surface snow at Dome C. We note that the slope of the delta O-18 vs. temperature (T) relationship decreases in these samples compared to those from the traverses, and thus caution is advocated when using spatial ...