Summary of the Two Shallow Firn/Ice Cores (NEEM07S3 and NEEM08S3A) Used in the Paper a

Several shallow cold / ice cores were drilled around the camp as part of the exploration program to help explain the stable isotope record along the deep ice core. By investigating these short cores the annual resolution of NEEM's δ 18 O recording was shown to be associated with annual and winter North Atlantic Oscillation (NAO) signals (Steen-Larsen et al., 2011; Masson-Delmotte et al., 2015). This is in contrast to δ 18 O records from central and southern Greenland, which are closely related to winter NAO signals (Vinther et al., 2003 (Vinther et al., 2010)).

As expected, the correlation with southwest Greenland between 1949 and 2004 shows similar dependence on the Pituffik observatory in Figures 2b and D and supports changes in the relationship between δ18O and west in winter did. This weakly changing correlation of δ 18 O over time in Greenland seems to be due to intermittent and cold precipitation of NEEM (Steen-Larsen et al., 2011). The correlation between SWG Greenland in Greenland in 1949 in 2004 shows that the correlation between the increase in annual accumulation in summer (80% from April to November) and the lowest winter temperature (20% of peak) It shows that it is most important. .

The ice core is a vertical pillar that passes through glaciers and samples layers formed by annual snowfall and melting. As snow accumulates, each layer is pressed against the lower layer, making them denser until it becomes fir. The density of Firn is not enough to prevent escape of air, but it is ice at a density of about 830 kg / m 3, the internal air is confined in bubbles, and atmospheric constituents are confined as ice is formed I will. The depth of this situation varies from location to location, but in Greenland and Antarctica it ranges from 64 to 115 meters. Because the snowfall rate varies from place to place, the age at snowfall greatly differs. The depth of the Summit Camp in Greenland is 77 meters and there is a history of ice over 230 years In Dome C of Antarctica, the depth is 95 meters and the age is 2,500 years. Bubbles will disappear and ice will become more transparent

Ice cores are core samples that are typically taken from ice sheets and alpine glaciers. Since ice is formed by the recruitment of annual snow layer, the lower layer is faster than the upper layer and the ice core contains ice formed over the years. Drill a hole with a hand drill (shallow hole) or a power drill; they can reach a depth of 2 miles (3.2 km) or more and can contain ice up to 800,000 years. The physical properties of ice and the substances trapped in it can be used to rebuild the climate within a central age range. Different oxygen isotopic ratios and hydrogen isotope ratios provide information on ancient temperatures and can analyze the air trapped in small bubbles to determine the level of atmospheric gases such as carbon dioxide. The heat flow in the large ice sheet is very slow, so the well temperature is another indicator of the past temperature.