STUDY ON SPATIOTEMPORAL CHARACTERISTIC OF OBSERVATION IMPACT IN PROXY DATA ASSIMILATION

Abstract

 Climate reconstruction enables us to analyze long-term climate change. Understanding climate change is the key to improving climate prediction. In this study, we confirmed that annual variations of temperature for the past 1000 years can be reconstructed by data assimilation using oxygen isotopic data of ice cores, corals, and tree-ring cellulose, based on the previous study (Okazaki and Yoshimura, 2017). However, it’s difficult to reconstruct climate fields if proxies are sparse temporally and spatially. Even so, proxies’ impact on analysis does not always depend on the amount of proxies’ data. It is possible that about 20% proxies can reconstruct the past climate as same as all proxies used in this study, although observation impact is different spatiotemporally. Coral proxies in the central tropical Pacific appear to be the most effective for climate reconstruction by data assimilation.