HR: 11:50h
AN: B32A-07    [Abstracts]
TI: First results from coupling carbon cycle, nitrogen cycle, and climate in the NCAR CCSM3 model.
AU: * Thornton, P E
EM: thornton@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80305 United States
AB: First results are presented describing both the offline performance of a coupled carbon-nitrogen cycle model operating within the NCAR Community Land Model (CLM-CN), and the coupled performance of CLM-CN operating within the NCAR Community Climate System Model, Version 3 (CCSM3). The new land model is fully prognostic for all energy, water, carbon, and nitrogen pools in the vegetation, litter, and soil. Atmospheric nitrogen deposition is prescribed from an offline atmospheric chemistry model for preindustrial, current and projected rates at 2100. The land model includes a relatively simple treatment of fire frequency and fractioanl area burned. Offline results demonstrate that CLM-CN performs well when driven with observed surface weather forcings. Experiments are performed in both coupled carbon-nitrogen mode and carbon-only mode to demonstrate the influence of this coupling on land net carbon fluxes. Experiments in offline mode show that the response of the carbon-only and carbon-nitrogen models to imposed warming is fundamentally different, with different time constants and different geographic distributions of sources and sinks. Coupled experiments demonstrate the influence of these dynamics on the evolution of land-atmosphere feedbacks under conditions of increasing fossil fuel consumption and shifting patterns of anthropogenic nitrogen deposition. The new model represents a significant step forward in our ability to represent multiple interactions among physical, biogeochemical, and anthropogenic components of the Earth System.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting