1Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Denmark
2Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, USA
3Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA-CNRS-UVSQ/IPSL 8212, Gif-sur-Yvette, France
4Department of Mathematics and Geosciences, Environmental and Marine Sciences, University of Trieste, Italy
5Laboratoire de Météorologie Dynamique, Jussieu, Paris, France
6ETH, Institute for Atmospheric and Climate Science, ETH Zürich, Switzerland
7Danish Climate Center, DMI, Lyngbyvejen 100, 2100 Copenhagen, Denmark
8Department of Geology, Lund University, Sölvegatan 12, SE-22362 Lund, Sweden
9Max-Planck-Institute for Biogeochemistry, 07745 Jena, Germany
10Institute of Science, University of Reykjavik, Dunhaga 3, Reykjavik 107, Iceland
11Institute of Arctic and Alpine Research, Campus Box 450, University of Colorado, Boulder, CO 80309, USA
Received: 25 Oct 2012 – Discussion started: 14 Jan 2013
Abstract. We present here surface water vapor isotopic measurements conducted from June to August 2010 at the NEEM (North Greenland Eemian Drilling Project) camp, NW Greenland (77.45° N, 51.05° W, 2484 m a.s.l.). Measurements were conducted at 9 different heights from 0.1 m to 13.5 m above the snow surface using two different types of cavity-enhanced near-infrared absorption spectroscopy analyzers. For each instrument specific protocols were developed for calibration and drift corrections. The inter-comparison of corrected results from different instruments reveals excellent reproducibility, stability, and precision with a standard deviations of ~ 0.23‰ for δ18O and ~ 1.4‰ for δD. Diurnal and intraseasonal variations show strong relationships between changes in local surface humidity and water vapor isotopic composition, and with local and synoptic weather conditions. This variability probably results from the interplay between local moisture fluxes, linked with firn–air exchanges, boundary layer dynamics, and large-scale moisture advection. Particularly remarkable are several episodes characterized by high (> 40‰) surface water vapor deuterium excess. Air mass back-trajectory calculations from atmospheric analyses and water tagging in the LMDZiso (Laboratory of Meteorology Dynamics Zoom-isotopic) atmospheric model reveal that these events are associated with predominant Arctic air mass origin. The analysis suggests that high deuterium excess levels are a result of strong kinetic fractionation during evaporation at the sea-ice margin.
Revised: 15 Mar 2013 – Accepted: 05 Apr 2013 – Published: 13 May 2013
Steen-Larsen, H. C., Johnsen, S. J., Masson-Delmotte, V., Stenni, B., Risi, C., Sodemann, H., Balslev-Clausen, D., Blunier, T., Dahl-Jensen, D., Ellehøj, M. D., Falourd, S., Grindsted, A., Gkinis, V., Jouzel, J., Popp, T., Sheldon, S., Simonsen, S. B., Sjolte, J., Steffensen, J. P., Sperlich, P., Sveinbjörnsdóttir, A. E., Vinther, B. M., and White, J. W. C.: Continuous monitoring of summer surface water vapor isotopic composition above the Greenland Ice Sheet, Atmos. Chem. Phys., 13, 4815-4828, doi:10.5194/acp-13-4815-2013, 2013.