Journal
CLIMATE OF THE PAST
Volume 13, Issue 4, Pages 379-393Publisher
COPERNICUS GESELLSCHAFT MBH
DOI: 10.5194/cp-13-379-2017
Keywords
-
Funding
- Japan Society for the Promotion of Science (JSPS)
- Japan Society for the Promotion of Science [15H01729, 26289160, 23226012]
- SOUSEI Program
- ArCS project of MEXT
- Japanese Ministry of the Environment [S-12]
- CREST program of the Japan Science and Technology Agency
- Japan Society for the Promotion of Science (JSPS)
- Japan Society for the Promotion of Science [15H01729, 26289160, 23226012]
- SOUSEI Program
- ArCS project of MEXT
- Japanese Ministry of the Environment [S-12]
- CREST program of the Japan Science and Technology Agency
- Grants-in-Aid for Scientific Research [17K14397, 26289160, 15H01729, 15KK0199, 16H06291] Funding Source: KAKEN
Ask authors/readers for more resources
Data assimilation (DA) has been successfully applied in the field of paleoclimatology to reconstruct past climate. However, data reconstructed from proxies have been assimilated, as opposed to the actual proxy values. This prevented full utilization of the information recorded in the proxies. This study examined the feasibility of proxy DA for paleoclimate reconstruction. Isotopic proxies (delta O-18 in ice cores, corals, and tree-ring cellulose) were assimilated into models: an isotope-enabled general circulation model (GCM) and forward proxy models, using offline data assimilation. First, we examined the feasibility using an observation system simulation experiment (OSSE). The analysis showed a significant improvement compared with the first guess in the reproducibility of isotope ratios in the proxies, as well as the temperature and precipitation fields, when only the isotopic information was assimilated. The reconstruction skill for temperature and precipitation was especially high at low latitudes. This is due to the fact that isotopic proxies are strongly influenced by temperature and/or precipitation at low latitudes, which, in turn, are modulated by the El Nino-Southern Oscillation (ENSO) on interannual timescales. Subsequently, the proxy DA was conducted with real proxy data. The reconstruction skill was decreased compared to the OSSE. In particular, the decrease was significant over the Indian Ocean, eastern Pacific, and the Atlantic Ocean where the reproducibility of the proxy model was lower. By changing the experimental design in a stepwise manner, the decreased skill was suggested to be attributable to the misrepresentation of the atmospheric and proxy models and/or the quality of the observations. Although there remains a lot to improve proxy DA, the result adequately showed that proxy DA is feasible enough to reconstruct past climate.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available