ALBERT

Beschreibung: The drill of the EPICA Dome C ice core has been completed almost 20 years ago. This ice core already provided many reference records for climate and atmospheric greenhouse gase concentrations over the last 800,000 years, hence covering 9 glacial interglacial transitions or glacial terminations. These records combined to records from other archives have already shown the diversity in term of amplitudes and durations of the last 9 glacial terminations occurring in different orbital contexts. Still, the relatively low resolution of the current records hampered a good chronology of the oldest deglaciations as well as the study of the rapid climatic variability at centennial to multi-millennial scale superimposed to the longer term orbital climatic variability. Here, we will present high resolution measurements of water and air isotopes on the EPICA Dome C ice core over the last 800,000 years with a particular focus on glacial terminations. These new data enable to improve the chronology of the EPICA Dome C ice core hence improving the link between orbital forcing and climatic variability, especially for the period between 800,000 years and 200,000 years before present. In addition, our relatively high resolution records (50-300 years) of water and air isotopes enable us to describe on the same chronology the occurrence of millennial scale variability in the low to mid latitudes over the terminations 2, 3, 4 and 5 (occurring between 440,000 and 120,000 years before present) while local climate at the drilling site of EPICA Dome C has a much smoother evolution.

Beschreibung: Dome C is located on the high Antarctic plateau, at 3233m above sea level, and 1200km away from the coastline. At this location, the EPICA ice core was retrieved from the ice sheet and allowed the reconstruction of past climatic information 800,000 years back in time. Amongst several atmospheric parameters, the past local temperature was inferred from the stable water isotope record measured in the ice.To interpret this record, it is necessary to understand how it was formed in such a dry and cold environment. This includes understanding the water cycle dynamics in Antarctica, from evaporation to precipitation and moisture pathways, as well as the processes affecting the record after deposition of the precipitation, such as snow-atmosphere exchanges.During the austral summer 2018-2019, a Picarro laser spectrometer was installed on site to monitor continuously the isotopic composition of the atmosphere. It provided measurements for all austral summers since then and allowed the detection of two major atmospheric river events, including a rare event during the onset of the cold Antarctic winter. To go beyond the limitations of the Picarro instrument when measuring at very low humidity levels, as encountered during the wintertime at Dome C, a new laser spectrometer dedicated to low humidity measurements has been developed and installed it in parallel to the Picarro instrument during the summer season 2022-2023. Here we present the results of the atmospheric isotopic composition during four consecutive austral summers and the comparison of the two laser instruments during the most recent period.