Investigating the possibility to retrieve climate information from three stacked δ18O series in Adélie Land: a comparison between data and virtual firn cores

Water stable isotopes signals recorded in snow, firn and ice cores were successfully used to investigate past temperatures on glacial/interglacial scales. However, many uncertainties hampered the interpretation of water isotope records at sub-annual to decadal resolution as a proxy of past temperature variations only. Condensation, sublimation and/or redistribution of snow triggered by strong katabatic winds as well as diffusion within firn lessen the representativeness of a single isotopic profile to reconstruct past temperature in this region. In order to mitigate the non-representativeness of a single isotopic profile, a solution consists of averaging several records to increase signal to noise ratios.

              In this study, we present an analysis of 3 stacked δ¹⁸O temporal series from the coast-to-plateau transition in Adélie land. Each of these stacks was built from three shallow firn cores (~20 m-long) drilled at 3 locations (so called D47, Stop5 and Stop0) with high accumulation rates (~200 mm w.eq ·yr^-1) during the ASUMA campaign in December 2016 - January 2017. The sites feature different elevations (from 1516 m to 2416 m above sea level) and katabatic winds influence. We present a comparison of each of these stacks with virtual firn cores produced from the outputs of two atmospheric general circulation models including isotopes, ECHAM6wiso and LMDZ6iso for the period 1979 - 2016. In particular, we show how much of the climatic information we can retrieve from our δ¹⁸O stacked series.