[M-IS16] Paleoclimatology and paleoceanography

[MIS16-10] Evaluation of proxy system models for stable water isotopes and introduction of their application to paleoclimate studies

★Invited Papers

*Okazaki Atsushi¹, Kei Yoshimura² (1.The Pennsylvania State University, 2.The University of Tokyo)

Keywords:proxy system models, stable water isotopes, data assimilation, paleoclimate reconstruction

Proxy system models (PSMs) are an important bridge between climate simulations and climate records prior to the period where instrumental observations are available. PSMs help to interpret what proxies show and how they record climate. Although previous studies have evaluated PSMs for individual sites, their systematic evaluation on a global scale has not been conducted. This study evaluated the performance of PSMs for stable water isotopes in ice cores, corals, and tree-ring cellulose for the period 1950–2007. We used an isotope enabled atmospheric GCM named MIROC5-iso to provide input data for the PSMs. MIROC5-iso was nudged toward NCEP/NCAR Reanalysis to synchronize the model with nature. The evaluation result shows that the mean state and the variability were generally well simulated for all proxy types. However, the reproducibility of interannual variability in ice cores was markedly lower. Although the reproducibility was limited by the atmospheric forcing used to drive the model, the results suggest that the PSM may be missing post-depositional processes, such as sublimation for ice cores on the interannual time scale.
In the presentation, recent studies on paleoclimate data assimilation as an application of PSMs will be also introduced.