Stable isotopes in the atmospheric marine boundary layer water vapour over the Atlantic Ocean, 2012–2015

The water vapour isotopic composition (1H216O, H218O and 1H2H16O) of the Atlantic marine boundary layer has been measured from 5 research vessels between 2012 and 2015. Using laser spectroscopy analysers, measurements have been carried out continuously on samples collected 10–20 meter above sea level. All the datasets have been carefully calibrated against the international VSMOW-SLAP scale following the same protocol to build a homogeneous dataset covering the Atlantic Ocean between 4°S to 63°N. In addition, standard meteorological variables have been measured continuously, including sea surface temperatures using calibrated Thermo-Salinograph for most cruises. All calibrated observations are provided with 15-minute resolution. We also provide 6-hourly data to allow easier comparisons with simulations from the isotope-enabled Global Circulation Models. In addition, backwards trajectories from the HYSPLIT model are supplied every 6-hours for the position of our measurements.CSL acknowledge support from AXA Research Fund, the Carlsberg Foundation, and the Danish Council for Independent Research-Natural Sciences grant number 10-092850. AKF acknowledges support from the Danish National Research Foundation. Fieldwork carried out onboard the ACTIV cruise was part of the X_Centuries project funded by the Danish Council for Independent Research (FNU) (grant number DFF-0602-02526B) and the Centre for GeoGenetics supported by the Danish National Research Foundation (DNRF94). The authors thank the captain and crew of the ACTIV cruise. Work during Strasse on R/V Thalassa and Pirata FR24 on R/V Suroit was supported by three LEFE/IMAGO grants (Strasse, Strasse/SPURS and PIRATA), with additional support for equipment from IPSL and from OSU Ecce Terra. The authors gratefully acknowledge the help of the association 'Les Amis du Jeudi et du Dimanche' for the installation of the scientific instrumentation on the RARA AVIS. The authors also thank the PIRATA program for providing free precious data sets to the whole scientific community. The authors thank the TOSCA-SMOS program which founding was used for installing the SBE45 onboard the RaRa Avis Vessel. The authors thank Floriane Desprez de Gezincourt (LOPS) for her help setting up the TSG on the RaRa Avis and for her contribution in analyzing salinity of the water samples. The authors also gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and/or READY website (http://www.ready.noaa.gov) used in this publication. ERA-Interim data provided by courtesy of ECMWF.Peer Reviewe