Constraining the Climatic Signal Archived in Water Isotopes in Antarctic Ice Cores

• Applicant: Professorin Dr. Kira Rehfeld, since 2/2022
• Subject Area: Atmospheric Science
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 442926051

Antarctica is a major component of the climatic system: the enormous amount of ice interacts with the atmosphere and the ocean and plays a determinant role in the radiative budget of the earth, the oceanic and the atmospheric circulations. In central Antarctica, the climate change signature in the short and sparse instrumental record is hidden below strong inter-annual variability. Fortunately, the isotopic composition stored in ice cores provides records of past climates both at short time scales (anthropogenic period), and at long time scales (glacial/interglacial cycles). This enables to put the present temperature variations of Antarctica in the context of the last millennia and to compare it with analogue situations from the past. Still, the interpretation of the water isotopic signal, especially at high temporal resolution, is limited by poorly understood post-deposition processes, which cannot be neglected on the East Antarctic Plateau. This project focuses on understanding the archival of the climatic signal in the isotopic composition in the Dome C region, where the oldest ice records are available. The purpose is to improve the power to reconstruct past climate variations by understanding how climate variations are imprinted in the ice isotopic composition. This will be realised by identifying the sources of noise that hides the climatic signal in the ice isotopic composition, in particular stratigraphic noise, which is characterised by small (< 5m) decorrelation length, and precipitation intermittency noise, which is characterised by large (> 100km) decorrelation length. Relying both on a mechanistic approach based on year-long monitoring of the exchanges between vapour and ice, and statistical analysis of snow isotopic variability in a large dataset from all around Dome C, we will generalise the process understanding into an understanding of water isotopes as climate proxy. The work builds on the most advanced techniques in infrared spectroscopy, advanced statistical techniques and collaborations with other institutes through direct interactions and field work. It will enable

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1158: Infrastructure area - Antarctic Research with Comparative Investigations in Arctic Sea Ice Areas
• Ehemaliger Antragsteller: Dr. Mathieu Casado, until 1/2022