CESM2 default initial condition and spin-up?

[mengqi]

Hi,

I am working with CESM2 and have set up and built an FHIST_BGC case. When checking the CaseDocs/lnd_in file, I noticed that a default initial condition input (i.e., finidat) is specified.

finidat = '/glade/campaign/cesm/cesmdata/inputdata/lnd/clm2/initdata_map/clmi.BHIST.2000-01-01.0.9x1.25_gx1v7_simyr2000_c181015.nc'

My question is: Why does the case provide a default initial condition file? Does this mean I do not need to perform a spin-up simulation, or that I conduct an additional spin-up simulation to replace that default initial file?

Thanks!

M.

 

[slevis]

The model provides default initial conditions for certain compset-grid combinations to allow users to begin meaningful simulations sooner. HOWEVER, before starting production runs that you intend to use in publications, make sure that you are satisfied with the initial conditions because you will need to document them in your papers. In that case, you may decide to complete your own spin-up.

 

[mengqi]

Thank you so much, @slevis!

By the way, I’m not sure how to properly document the default initial conditions in my paper. Could you please provide an example showing how they are originally specified? Thanks!!

 

[slevis]

The simplest approach that I can think of is to document as follows in the Methods section:
- the exact version of the model that you are running, along with the references describing that version in the literature
- the exact compset-grid combination that you used in your simulations
- I would also name the exact initial condition files and other default files that you may have used, and this could be done in the supplemental materials if not in the main paper

This approach allows readers of your papers to reproduce your work if they so wish. You may think of additional information that you can provide.