TY  - STD
AU  - Scarlett Boiardi
PY  - 2015//
TI  - The isotopic composition of water vapour in theSvalbard and the atmospheric circulation
N2  - Understanding the meteorological drivers of precipitation isotopic composition is crucial for theinterpretation of paleoclimate archives, such as the past precipitation records found in the icecores, as well as to successfully constrain atmospheric models including the explicitrepresentation of water isotopes. This is of particular importance in the context of climate change,and in particular in the Arctic where climate models project enhanced hydrological cycle andtemperature increase which might in turn have significant impacts on the global climate (throughe.g. the sea-ice retreat, water vapour feedback or cloud cover). Indeed, large discrepancies on thefuture Arctic precipitation exist amongst different climate models.Condensing water vapour being the first stage of a precipitation event, its isotopic compositioninfluences that of the precipitation and must therefore be fully understood in order to find thecauses for the inter-model spread. The water vapour isotopic composition is believed to beinfluenced by changes in moisture sources and fractionation history during transport. It thusprovides valuable and independent information on moisture source origins and represents acrucial tool for assessing the realism of models and the interpretation of meteorological archives.During the last 5 years, new laser methods have permitted to achieve such measurements of waterisotopes.In the present work, new in situ continuous measurements of the isotopic composition of watervapour in Svalbard between the end of June 2014 and March 2015 are studied. Given its location,Svalbard allowed us to expand the monitoring of water vapour isotopic composition andatmospheric circulation towards the Arctic so as to explore their relationship to the moisturesource conditions. In order to do so, Lagrangian backtrajectories were computed and associatedwith the processed data.A clear distinction between trajectories coming from over the Arctic sea-ice area and those fromthe North Atlantic Ocean could be observed in the isotopic composition. The latter also displayedseasonal variations attributed to seasonal changes in atmospheric transport. Moreover, duringdays with low isotopic depletion, deviations from the expected global meteoric water line wereobserved and studied. Finally, days displaying a significant and rapid change in the isotopiccomposition were explained by a corresponding sudden change in the air mass past trajectory.This work opens the possibility to quantify the effects of evaporation conditions on isotopic data,provides a new dataset for the evaluation of atmospheric models, and will provide a basis torevise the climatic interpretation of Svalbard ice core records.
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ID  - ScarlettBoiardi2015
ER  -