Protocol: revised Sept 20 2002 Click here to retrieve


Consider:
  • Radiative CO2
  • Biogeochemical CO2 (influences plant function)
  • Tracer CO2 (for diagnostic or surface fluxes)
Recommend:
  • BYOM - Bring Your Own Model
    C4MIP does not decree minimal (or maximum) carbon cycle model
  • Include CO2 as tracer in atm model
  • Carry diagnostic tracers: C14, CFC, radon...
Experimental Protocol:
    I. Spin-up: Preindustrial

      Forcing: No external C sources/ sinks

      Initial conditions: atm CO2 = 280 ppmv

      Experiment:

      Diagnostics:

    II. Contemporary: AD 1850-2100

      Forcing: Fossil fuel CO2 flux (x,y,t) (Marland/Andres)

      Initial Conditions:

      • Climate and C fields from control Run
      • Duration of run : 1850 - 2100

      Experiment: Fully interactive C and Climate

      Diagnostics:

      Issues:

      • Interannual and interdecadal climate variability in CGCM may not be realistic - difficult to interpret carbon variability
          => Terrestrial and Oceanic Carbon states for AD2000

    III. Permissible Emissions

    d/dt[CO2] =  {Fba - Fab}  + /font> {Fao - Foa}  +  Sources/Sinks
    Specified ?

    • Specify CO2 to increase linearly,then stabilize at 450 ppmv (... other scenarios?)
    • Estimate terrestrial and oceanic fluxes using to force BGC modules forced by :
      • "present-day climate"
      • CMIP climate?

    IV. Prognostic

      C4:
        1. Control (C4): 280 ppmv
        See Peter Cox re spin-up
        2. Basic Experiment: 
        • Forcing: Specify CO2 Emission
            • 1850 -> 1995: historical Fossil Fuel emission (Marland and Andres)
            1995 -> +100 years: IS92A or SRESxx 
            This is a "clean" theorical sensitivity experiment.
            Not directly comparable to observations in historical period.
        • Initial condition: from control
        • Experiments: 
            (I) fully coupled, 
            • prognostic radiative and BGC CO2
            • vegetation: dynamic or static depends on capability of model, run both if possible
            (II) fully coupled, but 
            • radiative CO2=280ppmv
              This experiment explores biophysical and BGC feedbacks)
            (III) ...
        3. Alternative forcing: like 2, + other radiative forcing for 1850-1995
        Comparable to carbon and climate obs
        As long as radiative forcing are comprehensive.
        (not likely, since no land use change)
      Permissible Emissions:
        CMIP

        1. Control climate from CGCM: radiative CO2= 280 ppmv, no carbon cycle

        2. Transient climate from CGCM: prescribed CO2(t) 1850-2000

        Archive surface climate for forcing
        Terrestrial and oceanic carbon models.
        6-hourly for some terrestrial C models, monthly for others.
        Off-line and land ocean carbon cycle models:
        • Atm CO2=prescribed CO2(t) from CMIP transient run
        • Forced by
          • control climate
          • transient climate
        • Calculate carbon uptake by land and sea
        • Permission emission = dCO2/dt + sinks
        Encourage collaboration between groups with no GCM's
        and groups with no carbon cycle models

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