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Changing planetary properties in all CESM components


Cecile Hannay
AMWG Liaison
Staff member
From user:

We are trying to modify CESM/WACCM to simulate various types of planets. So far, we have successfully changed the rotation rate, the gravitational acceleration, and the Earth's radius, by making the following changes in user_nl_cam:

omega = 0.000006502178685
sday = 966320
gravit = 13.9665
rearth = 6816970

These changes do not seem to propagate through to other parts of the model, including the ocean where these changes would likely have a large impact. I have looked at the namelist options online (CESM2 Driver Namelist Definitions and CESM2 POP2 Namelist Definitions), but these variables only seem to exist for the atmosphere. Do you know how we could get these changes to work in all parts of the model?

Greg Cooke

Greg Cooke
New Member
To do this, I modified shr_const_mod.F90. If you modify some of the variables in that file, then the changes propagate through to the ocean. See an example below:

real(R8),parameter :: SHR_CONST_SDAY = 432000.0_R8 ! sec in siderial day ~ sec
real(R8),parameter :: SHR_CONST_OMEGA = 2.0_R8*SHR_CONST_PI/SHR_CONST_SDAY ! earth rot ~ rad/sec
real(R8),parameter :: SHR_CONST_REARTH = 5.1e6_R8 ! radius of earth ~ m
real(R8),parameter :: SHR_CONST_G = 9.0_R8 ! acceleration of gravity ~ m/s^2

I am not sure if you also have to change user_nl_cam in order to get the changes in the atmosphere too, and this is something I will be investigating.