Models - Land Model
BCC_AVIM1.0 is originated from the Atmosphere and Vegetation Interaction Model (AVIM, Ji, 1995) and includes three sub-modules: biogeophysical, ecophysiological and soil carbon-nitrogen dynamical modules. A modified biogeophysical framework with 10-layer soil and at most 5-layer snow is almost the same as that in the NCAR Community Land Model version 3.0 (CLM3, Oleson et al., 2004). Since the snow cover fraction (SCF) is underestimated in CLM3 which is similar to that in BATS (Yang, 1997),, the scheme calculating SCF in BCC_AVIM1.0 is based on the work of Yang (1997) which improves the SCF in thin snow covered area and the work of Roesch (2001) which takes into account the influence of sub-grid topography variability on SCF.
The terrestrial carbon cycle in BCC_AVIM1.0 operates through a series of biochemical and physiological processes: photosynthesis and aututropic respiration of vegetation, allocation of carbohydrate to leaves, stem, and root tissues, carbon loss due to turnover and mortality of vegetation, and CO2 release into atmosphere through soil respiration.
In BCC_AVIM1.0, the litterfall of leaves and fine roots goes into aboveground as well as belowground carbon pools, the decomposition rate of soil carbon and transfer among different soil carbon pools are dependent on the life time of carbon in each carbon pool and the temperature and moisture conditions of the soil (Cao, 2004). Carbons stored in the soil are finally return to the atmosphere through soil heterotrophic respiration.
The integration time step is 20 minutes for the photosynthesis of vegetation and 24 hours for the biomass accumulation and phonological variation and soil carbon decomposition processes. The vegetated surfaces are divided into 15 plant functional types (PFTs) including natural vegetation and crop as the present situation. In BCC_AVIM1.0, a grid cell contains up to four PFTs.
BCC_AVIM1.0 has been coupled into BCC_CSM1.1 through flux coupler and conducted a series of CMIP5 experiments.
Cao M., and F. I. Woodward, 1998: Net primary and ecosystem production and carbon stocks of terrestrial ecosystems and their responses to climate change. Global Change Biology, 4, 185-198.
Ji, J., 1995: A climate-vegetation interaction model: simulating physical and biological processes at the surface. J. Biogeogr, 22, 2063-2069.
Oleson, K. W., Yongjiu Dai, G. Bonan et al., 2004, Technical description of the Community Land Model [R]. NCAR Tech. Note NCAR/TN-461+STR, 174pp.
Roesch, A., M. Wild, H. Gilgen, A. Ohmura. A new snow cover fraction parameterization for the ECHAM4 GCM [J]. Climate Dynamics, 2001, 17: 933-946.
Yang, Z.-L., R. E. Dickinson, A. Robock, and K. Y. Vinikov, Validation of the snow sub-model of the biosphere-atmosphere transfer scheme with Russian snow cover and meteorological observation data [J]. Journal of Climate, 1997, 10:353-373.
Ji, J., M. Huang, and K. Li, 2008: Prediction of carbon exchange between China terrestrial ecosystem and atmosphere in 21st century. Science in China series D: Earth Science, 51(No. 6): 885-898.