Using a process-based dendroclimatic proxy system model in a data assimilation framework: a test case in the Southern Hemisphere over the past centuries

Jeanne Rezsöhazy (1, 2) , Quentin Dalaiden (2) , François Klein (2) , Hugues Goosse (2) , Joel Guiot (1)

1 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
2 UCL - Université Catholique de Louvain = Catholic University of Louvain

Currently available data-assimilation-based reconstructions of past climate variations have only used statistical proxy system models to make the link between climate model outputs and indirect observations from tree rings. However, the linearity and stationarity assumptions of the statistical approach may have limitations. In this study, we incorporate the process-based dendroclimatic model MAIDEN into a data assimilation procedure using the reconstruction of near-surface air temperature, precipitation and winds in the midlatitudes of the Southern Hemisphere over the past 400 years as a test case. We compare our results with a data assimilation approach including a linear regression as a proxy system model for tree-ring width proxies. Overall, when compared to instrumental data, the reconstructions using MAIDEN as a proxy system model offer a skill equivalent to the experiment using the regression model. However, knowing the advantages that a process-based model can bring and the improvements that can still be made with MAIDEN, those results are promising.

Domaines: Planète et Univers [physics]; Sciences de la Terre

Jeanne Rezsöhazy, Quentin Dalaiden, François Klein, Hugues Goosse, Joel Guiot. Using a process-based dendroclimatic proxy system model in a data assimilation framework: a test case in the Southern Hemisphere over the past centuries. Climate of the Past, 2022, 18, pp.2093-2115. ⟨10.5194/cp-18-2093-2022⟩. ⟨insu-03824751⟩