Total Air Content measurements from the RECAP ice core
Abstract. Total air content (TAC) of the REnland ice CAP project (RECAP) core, drilled in summer 2015, is measured as a part of investigating the elevation history of the Greenland Ice Sheet (GIS). TAC is a proxy for the elevation at which the ice was originally formed as the TAC in ice cores is predominantly influenced by surface air pressure and conditions like temperature and local summer insolation. The RECAP TAC data shows incoherently low values in the Holocene climatic optimum (6 to 9 kyr b2k) and in the Eemian (119 to 121 kyr b2k) which renders the TAC data unfit for paleo elevation interpolation. In contrast, the glacial section (11.7 kyr to 119 kyr b2K) has consistent TAC values thus in principle facilitating the past elevation calculations. However, we observe TAC variations related to Dansgaard-Oeschger events (D-O) that cannot originate from elevation changes but must be linked to changes in the firn structure. We analyse the pattern of the structural changes in the RECAP and NGRIP cores. For the melt affected sections (Holocene and Eemian) we use melt affected TAC to reconstruct summer temperatures.
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