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"Quantitative picture of interactions between climate, hydrological cycle and stratospheric inputs in Antarctica over the last 100 years via the combined use of all water isotopes" (COMBINISO)
Date du début: 1 janv. 2013, Date de fin: 31 déc. 2017 PROJET  TERMINÉ 

"Climate change and associated water cycle modifications have a strong impact on polar ice sheets through their influence on the global sea-level. The most promising tool for reconstructing temperature and water cycle evolution in Antarctica is to use water isotopic records in ice cores. Still, interpreting these records is nowadays limited by known biases linked to a too simple description of isotopic fractionations and cloud microphysics. Another key issue in this region is the stratosphere-troposphere flux influencing both the chemistry of ozone and decadal climate change. Data are lacking for constraining such flux even on the recent period (100 years). COMBINISO aims at making use of innovative methods combining measurements of the 5 major water isotopes (H217O, H218O, HTO, HDO, H2O) and global modelling to address the following key points: 1- Provide a strongly improved physical frame for interpretation of water isotopic records in polar regions; 2- Provide a quantitative picture of Antarctica temperature changes and links with the tropospheric water cycle prior to the instrumental period; 3- Quantify recent variability of the stratosphere water vapor input.The proposed method, based on strong experimental – modelling interaction, includes innovative tools such as (1) the intensive use of the recently developed triple isotopic composition of oxygen in water for constraining water isotopic fractionation, hydrological cycle organisation and potentially stratospheric water input, (2) the development of a laser spectroscopy instrument to accurately measure this parameter in water vapour, (3) modelling development including stratospheric tracers (e.g. HTO and 10Be) in addition to water isotopes in Atmospheric General Circulation Models equipped with a detailed description of the stratosphere, (4) a first documentation of climate, hydrological cycle and stratospheric input in Antarctica through combined measurements of isotopes in ice cores for the last 100 years."