[13] Ideas for new applications 1

[13-2] March 1, 13:40-14:00

Review and development of data assimilation for paleoclimate

Atsushi Okazaki (RIKEN), K. Yoshimura (University of Tokyo), and T. Miyoshi (RIKEN)


Knowledge of past climate conditions is crucial to understand the climate system. Recently, data assimilation (DA) has been applied to reconstruct paleoclimate, in which proxy data serves as observations. Here, proxies are not the direct record of climate variables such as temperature, winds, and pressure, but natural records representing climate such as tree-ring width and isotopic composition in ice sheets. DA has long been used for forecasting the weather and is a well-established method. However, the DA algorithms used for weather forecasts cannot be directly applied to paleoclimate due to the different temporal resolution, spatial extent, and type of information contained within the observation data. The temporal resolution and spatial distribution of proxy data are significantly lower (seasonal at best) and sparser than the present-day observations used for weather forecasts. Therefore, DA applied to paleoclimate is only loosely linked to the methods used in the more mature field of weather forecasting. Several DA methods have been proposed for paleoclimate reconstruction, and paleoclimate studies using DA have successfully determined the mechanisms behind the past climate changes. In this presentation, we review the previously proposed methods and develop a new method in which a proxy is directly assimilated for the first time.

  Presentation file: 13_2_A.Okazaki.pdf