Raman spectroscopic study on the nitrogen/oxygen ratio in natural ice clathrates in the GRIP ice core

We have carried out Raman spectroscopic experiments on air clathrates in the GReenland Ice Core Project (GRIP) deep ice core. We present new N-2/O-2 measurements that markedly differ from previous measurements of the Dye-3 ice core: the N-2/O-2 ratio we observe is much closer to atmospheric. This has new implications for the interpretation of gas distributions in ice sheets and the reconstruction of past atmospheric conditions.