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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, 51.05W, 2484ma.s.l.). Measurements
were conducted at 9 different heights from 0.1m
to 13.5m 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 intercomparison
of corrected results from different instruments
reveals excellent reproducibility, stability, and precision with
a standard deviations of 0.23‰ for 18O and 1.4‰ for D. 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
