AMOC-Millennia

The overall objective of this study is to shed light on Atlantic Ocean circulation variability and change during the last two millennia by combining climate model simulations with proxy data, using particle filter data assimilation, and to link this to climate variations over Europe. Specifically, we propose to reconstruct past changes in the oceanic circulation in the Atlantic and to analyze the interactions between ocean circulation and European climate over the past two thousand years, by combining terrestrial and marine proxy data with climate model simulations using an online data assimilation method. This will allow us to better understand the mechanisms responsible for multidecadal to centennial scale variability of the oceanic circulation in the Atlantic and to quantify their effect on the climate of the surrounding regions. This will also be the opportunity to evaluate the ability of models to reproduce this variability of the oceanic circulation and will contribute to the debate on the recent and future changes in the AMOC. This project will build on past work, utilizing the same particle filter assimilation technique as in Goosse (2017) [1] for instance, but the focus here will be on the North Atlantic and we will use more sophisticated models which allow a more detailed representation of the processes and more precise model-data comparison. Additionally, our experiments will assimilate not just terrestrial proxies but also marine proxies – to the best of our knowledge, we will be the first to attempt this for the past two millennia for the North Atlantic. The project is thus challenging both in term of the data selected and the models used but given the progress in model development, the recently dramatic improvement in available high-resolution proxy data and methodological advances for model-data comparison and data assimilation, the time is ripe now for this type of study. Our European cooperation partner is Prof. Hugues Goosse, Research Director F.R.S-FNRS, Professor UCLouvain, Belgium. [1] Goosse, H. (2017), Reconstructed and simulated temperature asymmetry between continents in both hemispheres over the last centuries, Clim. Dyn., 48(5-6), 1483-1501, doi: 10.1007/s00382-016-3154-z.