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Dating Model for Dome Fuji Ice Core using Data Assimilation
Understanding of past climate changes is regarded as a key for predicting the future climate. In particular, ice cores have been providing excellent records of the past climatic and environmental changes. The second Dome Fuji deep ice core (DF2 core) was drilled to 3,035 m below surface, and the comparison of its isotopic record with that of EDC core suggests that the DF2 core reaches ~700 kyr ago. In order to accurately date the core, one needs good estimation of accumulation rate and thinning function especially in the deep part (within ~500 m from the bed corresponding to ~340-700 kyr ago). The thinning function, which results from the horizontal stretching and vertical compression of an ice layer, is a function of several factors such as depth, temperature, basal sliding and geothermal heat flux.
Using Data Assimilation, we try to make a new dating method but based on the glaciological dynamics of Parrenin et al. (2004, 2007). Through filtering and smoothing method, we could gain a better tracking of the age of ice using high-resolution age makers for the deep part. It is still in the experimental stage, but we will introduce the method and indicate the results.