Following the successfull deployment of an instrument in June 2014, the ARCTISO-2 project aims at continuing and exploiting measurements of precipitation and water vapour isotopic composition at Ny Alesund (Svalbard). The isotopic composition of water vapour reflects the history of air mass trajectories, in relationship with evaporation conditions and distillation occurring along transportation, itself affected by cloud microphysical processes. Measurements in Ny Alesund are related to studies performed in different sites located in the North Atlantic (Bermuda, Iceland, north-west Greenland), in the Arctic (Siberia) complemented by transects (AWI PolarStern). These measurements will allow us to better understand the processes controlling water vapour isotopic composition, especially near the sea ice margin, to assess the ability of atmospheric models to resolve these processes, especially for deuterium excess. Together with backtrajectory and moisture transport calculations, these measurements will allow to estimate the fraction of moisture of local (Arctic) origin and the fraction of moisture which has been transported over long distance. In the context of an intensification of the Arctic water cycle, this fraction remains an important source of uncertainty. Finally, better understanding the processes controlling the water vapor isotopic composition will improve the interpretation of paleoclimate records such as those obtained from ice cores.