How do I change the orbital parameters in EdGCM?
In the Forcings section of the Setup Simulations window, there are fields where you can provide different values for eccentricity, axial tilt, and omegaT. If you enter a value into any of the three spaces then all three will be used to specify the orbital parameters for the simulation. In order to change the orbital parameters for a sensitivity test please follow these steps: • Create a new run. • Go to the Forcings section of Setup Simulations. • Set the three orbital parameters to the modern values instead of zero. The modern values for the orbital parameters are: • Eccentricity: 0.0167 • OmegaT: 282.9 • Axial tilt: 23.44 Orbital parameters require complex calculations of the precession of the orbit, which are not provide in EdGCM. You can, however, access a Fortran program called ORBPAR.f, which calculates the three orbital parameters as a function of year. ORBPAR.f was written by Dr. Gary Russell, one of the original authors of the NASA/GISS GCM (EdGCM’s climate model): Russell, Ga
