GRIP ice core detailed water isotope (δ18O) data

The ice core was drilled during the GRIP project in 1989-1992 at the Summit of the Greenland ice sheet. The length is 3025 m. Present-day accumulation 0.23 m ice/yr. Position 72.57N 37.62W, 3232 m a.s.l.. Data from the top 101.3 m comes from the S3 shallow core, but the two data sets have been fully integrated on a common depth scale. The delta-18O data were all measured immediately after the drilling (1989-90). The delta-18O data uncertainty is 0.1 per mil. All samples are cut in 2.5cm depth resolution and sample depths are for the bottom of each sample. As diffusion in the firn and snow degrade the annual signal, the data are also provided in a deconvoluted version that seeks to correct for this effect. Following the approach of S.J. Johnsen, the deconvolution uses an adaptive cut-off frequency permitting a fixed maximimum amplification (50) of the spectral components in the original data.