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www.biogeosciences-discuss.net/5/4001/2008/
doi:10.5194/bgd-5-4001-2008
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An empirical model simulating long-term diurnal CO2 flux for diverse vegetation types
1Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba 305-8506, Japan
2National Institute for Agro-Environmental Sciences, Tsukuba 305-8604, Japan
3Complex Systems Research Center, University of New Hampshire, Durham, NH 03824, USA
Abstract. We present an empirical model for the estimation of diurnal variability in net ecosystem CO2 exchange (NEE). The model is based on the use of a nonrectangular hyperbola for photosynthetic response of canopy and was constructed by using a dataset obtained from the AmeriFlux network and containing continuous eddy covariance CO2 flux from 26 ecosystems over seven biomes. The model uses simplified empirical expression of seasonal variability in biome-specific physiological parameters with air temperature, vapor pressure deficit, and precipitation. The physiological parameters of maximum CO2 uptake rate by the canopy and ecosystem respiration had biome-specific responses to environmental variables. The estimated physiological parameters had reasonable magnitudes and seasonal variation and gave reasonable timing of the beginning and end of the growing season over various biomes, but they were less satisfactory for disturbed grassland and savanna than for forests. Comparison with observational data revealed that the diurnal cycle of NEE was generally well predicted all year round by the model. The model gave satisfactory results even for tundra, which had very small amplitudes of NEE variability. These results suggest that this model with biome-specific parameters will be applicable to numerous terrestrial biomes, particularly forest ones.
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Citation: Saito, M., Maksyutov, S., Hirata, R., and Richardson, A. D.: An empirical model simulating long-term diurnal CO2 flux for diverse vegetation types, Biogeosciences Discuss., 5, 4001-4034, doi:10.5194/bgd-5-4001-2008, 2008. Bibtex EndNote Reference Manager XML
