A dynamical global vegetation model for studies of the coupled atmosphere-biosphere system

We present a new dynamical global vegetation model principally designed to be included in atmospheric general circulation models (AGCMs) or regional climate models. The model consists of a surface-vegetation-atmosphere transfer scheme coupled to a dynamical global vegetation model. It therefore simulates the principal processes of the continental biosphere influencing the global carbon cycle (photosynthesis, autotrophic and heterotrophic respiration of plants and in soils, fire, \ldots) as well as latent, sensible and kinetic energy exchanges at the surface of soils and plants. As a dynamical vegetation model, it explicitly represents competitional processes such as light competition, gaps, establishment, etc. It can thus be used in transient simulations of climate change, but it can also be used with a prescribed vegetation distribution. The whole seasonal phenological cycle is calculated prognostically without any prescribed dates or use of satellite data. The model is designed for an easy use as biosphere module in an AGCM, and first simulations with this model coupled to the LMDz atmospheric general circulation model are under way. This coupled hydrological-vegetation model is validated in stand-alone experiments against local observations of, for example, vegetation types, carbon stocks and fluxes. Simulated vegetation distribution and leaf area index in a global simulation is evaluated against observations.