| Volumes and Issues Contents of Issue 4 Special Issue |
www.biogeosciences-discuss.net/6/8455/2009/
doi:10.5194/bgd-6-8455-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Multi-model analysis of terrestrial carbon cycles in Japan: reducing uncertainties in model outputs among different terrestrial biosphere models using flux observations
1Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima, 960-1296, Japan
2Japan Agency for Marine-Earth Science and Technology, 3173-25, Showamachi, Kanazawa-ku, Yokohama, 236-0001, Japan
3QUEST, Department of Earth Science, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK
4National Institute for Environmental Studies, 16-2, Onogawa, Tsukuba, 305-8506, Japan
5Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, 599-8531, Japan
6Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
7National Institute for Agro-Environmental Sciences, 3-1-1 Kannondai, Tsukuba, 305-8604, Japan
8Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, 305-8687, Japan
9Field Science Center for Northern Biosphere, Hokkaido University, North 11-jo West 10-chome, Sapporo, 060-0809, Japan
Abstract. Terrestrial biosphere models show large uncertainties when simulating carbon and water cycles, and reducing these uncertainties is a priority for developing more accurate estimates of both terrestrial ecosystem statuses and future climate changes. To reduce uncertainties and improve the understanding of these carbon budgets, we investigated the ability of flux datasets to improve model simulations and reduce variabilities among multi-model outputs of terrestrial biosphere models in Japan. Using 9 terrestrial biosphere models (Support Vector Machine-based regressions, TOPS, CASA, VISIT, Biome-BGC, DAYCENT, SEIB, LPJ, and TRIFFID), we conducted two simulations: (1) point simulations at four flux sites in Japan and (2) spatial simulations for Japan with a default model (based on original settings) and an improved model (based on calibration using flux observations). Generally, models using default model settings showed large deviations in model outputs from observation with large model-by-model variability. However, after we calibrated the model parameters using flux observations (GPP, RE and NEP), most models successfully simulated seasonal variations in the carbon cycle, with less variability among models. We also found that interannual variations in the carbon cycle are mostly consistent among models and observations. Spatial analysis also showed a large reduction in the variability among model outputs, and model calibration using flux observations significantly improved the model outputs. These results show that to reduce uncertainties among terrestrial biosphere models, we need to conduct careful validation and calibration with available flux observations. Flux observation data significantly improved terrestrial biosphere models, not only on a point scale but also on spatial scales.
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Citation: Ichii, K., Suzuki, T., Kato, T., Ito, A., Hajima, T., Ueyama, M., Sasai, T., Hirata, R., Saigusa, N., Ohtani, Y., and Takagi, K.: Multi-model analysis of terrestrial carbon cycles in Japan: reducing uncertainties in model outputs among different terrestrial biosphere models using flux observations, Biogeosciences Discuss., 6, 8455-8502, doi:10.5194/bgd-6-8455-2009, 2009. Bibtex EndNote Reference Manager XML
