Dynamic Global Land Model

Members of Steve Pacala’s laboratory in collaboration with GFDL and USGS scientists have developed a new dynamic global land model, LM3. LM3 simulates the dynamics of vegetation and soil carbon pools, the state of hydrological cycle, the exchange of water, CO2, and energy exchange between land, atmosphere and ocean. LM3 is designed to study biosphere-atmosphere interactions and feedbacks: effects of changes in vegetation and soil functioning on the atmospheric physics and chemistry, and, reciprocally, the implication of changing climate and CO2 concentration on the land surface, and the implications of direct anthropogenic changes (i.e. land use) on the fate of climate and the global carbon cycle.

The model is designed to operate across the range of configurations from a stand-alone dynamic global vegetation model (DGVM) that is forced by prescribed climatic and soil data to a completely interactive component of a coupled Earth System Model that also includes general circulation models of the atmosphere and oceans with interactive biogeochemical cycles. When run as a stand-alone component, LM3 predicts the development and the state of global biosphere from the state of atmosphere (climate and CO2 concentration) and soil type. When coupled to an atmospheric model, LM3 also represents atmosphere-biosphere interactions by simulating the biophysical and biogeochemical feedbacks on the climate state.


Coupled Density-Coordinate Ocean Model

Another collaboration with GFDL led by Brian Arbic has made a density-coordinate ocean model more compatible with other models. A new grid has been developed for the Hallberg Isopycnal Model (HIM), and HIM has been converted from C code to Fortran code. This second development has allowed the HIM model to be coupled to GFDL’s ice and atmospheric models. New simulations with the coupled models will include perturbation anthropogenic carbon and chlorofluorocarbons, and in the future experiments will be run to assess the impact of physically motivated mixing schemes, driven by both wind and tidal energy inputs, on the oceanic general circulation and associated tracers.