Snow stable water isotopes of a surface transect at the EastGRIP deep drilling site, summer season 2017, 7 cm

Snow samples were taken on a daily basis along a 100 m wind-parallel transect at the EastGRIP ice core deep drilling site. The snow was collected at 11 positions with 10 m spacing in 2 depth intervals. The depth intervals are top 1 cm and top 7 cm. In addition, cumulative samples were taken from the top 1 cm depth interval. Each day, undisturbed snow was sampled and the exact sample location was marked to avoid sampling disturbed snow during the next sampling event. The samples were shipped frozen to the Alfred-Wegener-Institut and stored at -25°C. Before measurements, the samples were melted in the sample bags at room temperature. For the measurement of the isotopic composition, the instruments Picarro L2120-i and Picarro L2130-i were used. The measurement set-up followed the Van-Geldern protocol (Van Geldern and Barth, 2012). Each sample was injected 4 times. As a measure of accuracy, we calculated the combined standard uncertainty (Magnusson et al., 2017) including the long-term reproducibility and bias of our laboratory by measuring a quality check standard in each measurement run and including the uncertainty of the certified standards. The combined uncertainty for δ18O is 0.11 ‰ and for δ2H is 0.6 ‰.