Climate history at Aurora Basin North, East Antarctica: A 2,000 year isotopic record

In Antarctica, a reasonable coverage of ice core records exist for the last couple of hundred years, however there is poor spatial coverage of high-resolution climate data over the last 2000 years, particularly from East Antarctica (EA). The aim of the Aurora Basin North (ABN) ice core drilling project is to provide a 2000 year climate record from a data sparse area of EA to add to the IPICS 2k array and the PAGES Antarctica2k projects. ABN is a 303m ice core from EA, 550km inland and about half way between the coastal Law Dome and inland Dome C sites. Contiguous measurements of water stable isotope ratios (d18O and dD) have been performed along the entire length of the ABN ice core and provides a climate record at seasonal to decadal resolution for this region of EA spanning the past 2000 years. The isotopic variability at ABN shows clear annual cycles in the upper 50 m and longer-term variability on decadal to centennial timescales. The ABN record shows no long-term isotopic trend over the 2,000 year record length, similar to the four isotopic ice core records used in EA for the PAGES Antarctic 2k temperature reconstruction (PAGES2k, 2013). Mean ABN isotopic values (d18O -40.70 per mille, and dD -321.1 per mille) fall along the modern Antarctic spatial isotope/elevation and isotope/distance from the ocean relationships. The second order isotope parameter, deuterium excess (d) displays a relatively stable record (mean value of 4.4 per mille), with occasional sharp transitions to values as high as 8-10 per mille and as low as 0-1 per mille =. The large deuterium excess variations may reflect changes in moisture origin and evaporation conditions (SST, relative humidity). The isotopic variability at ABN therefore potentially reflects a mix of changes in transport and local climate (acting on precipitation intermittency and distillation strength), as well as local elevation changes. A comparison of the preliminary dated ABN isotope record with the Law Dome isotopic record shows that they are correlated, despite the differences in site-specific influences. This correlation indicates a common climate signal at both sites and a spatial coherence in regional climate from the coastal Law Dome to the inland plateau of the ABN site.