Direct isotope surface flux measurements calculated by the combination of an eddy-covariance instrument (Campbell Scientific Irgason) and a Picarro (L-2140i) cavity ring-down isotopologue gas analyzer. The averaging time was 25 minutes. The timestamp indicates the beginning of the averaging period. The measurement system was set up at 2.15m height and measured isotope fluxes above the snow surface from 25.05.2019-29.07.2019 at the EastGRIP site in the accumulation zone of the Greenland Ice Sheet. The data is processed and quality controlled.Flag 1 stands for highest quality, Flag 2 stands for accepted but probably underestimated flux estimates.