{"word_count": 297, "character_count": 1982}
The implementation of tritium in a GCM, and subsequent model-data comparison with a large available dataset, is a useful complement to the existing approach of using stable water isotope tracers. The method promises to provide better constraints on: (1) the intrusions and transport of air masses from the stratosphere and (2) the dynamics of the water cycle in the model. The next step will be to implement the bomb-tritium in LMDZ-iso. The atmospheric thermonuclear tests in the 1950s and early 1960s were indeed responsible for the massive injection of tritium in the atmosphere. The detailed information on these nuclear tests (dates, locations, altitudes, yields, etc) has now been released by governments and will be used to reconstruct a realistic atmospheric bomb-tritium input function. Simulations of bomb-tritium will be a very useful tool to evaluate the dynamics of the hydrological cycle in the LMDz-iso model in response to the bomb-tritium transient, and to revisit the issue of the stratospheric injections in relation to the modelled vertical advection.[caption id="attachment_243" align="alignnone" width="474"] (a) Moyenne annuelle du tritium dans les précipitations observée dans les données et (b) simulée dans LMDZ-iso. Notez que l’échelle de couleur n’est pas linéaire. (c) et (d) comme (a) et (b) mais pour la région Européenne, où les données GNIP de l’IAEA sont les plus abondantes. Les données utilisées ici sont des données GNIP (carrées) et des mesures pré-bombe (petits et grands cercles pour les limites basses et hautes respectivement).[/caption]Cauquoin, A., Jean-Baptiste, P., Risi, C., Fourré, E., Stenni, B., and Landais, A. The global distribution of natural tritium in precipitation simulated with an Atmospheric General Circulation Model and comparison with observations. Earth Planet. Sci. Lett., accepted.[1] TU : Tritium Unit, où 1 TU correspond à un rapport tritium/hydrogène de 10-18Cette étude est financée par l'ERC COMBINISO (306045)