Master 1 internship, Claire-Mathilde Stücki, supervised by Amaëlle Landais
Deep ice cores from the East Antarctic plateau provide a unique continuous record for paleoclimates [Petit et al., 1999]. The Beyond EPICA european project aims at reconstructing paleoclimates over the last 1.5Myr using an ice core drilled at Little Dome C. This drilling site is 34km away from Dome C, where EPICA ice core was drilled, and has very similar climatic conditions [Parrenin et al., 2017]. However, the first measurements show differences between the two ice cores in δ15N record that is a proxy for air lock-in depth. It is used to date the air bubbles that are analysed to reconstruct the past greenhouse gases concentration. It was found a difference of the firn thickness between the two sites of about 10%, that cannot be only explained by the differences in temperature and accumulation between the two sites. This study describes the differences between Dome C and Little Dome C and their implications for ice core dating, and suggests hypotheses to explain these differences. They might be due to variations in surface processes, with higher snow metamorphism and layering at Little Dome C, in relation with lower accumulation, and hence a higher residence time of snow at the surface.
