How the forcing files work into CICE5 (as part of CESM2)?

[Inchae Chung]

Hello.

I'm running CICE5 + DART, and it worked as a "coupled system", not "standalone system".
In my case, i used two components of forcing: atmosphere and ocean.
The atmosphere uses forcing data uploaded to NCAR RDA, and the ocean uses pop_frc.gx1v6.100513.nc obtained via check_input_data.

When considering forcing when using CICE5 as a "standalone system", i've used to deal with ice_forcing.F90.
However, I think that in the current "coupled system", forcing data is not operated by ice_forcing.F90.

So my question is, I wonder what process forcing goes through in this "coupled system".
I know that the xxx_in file is modified from the user_nl_xxx file and the xxx_in file is finally read, but I still don't understand how the input is read.

Thanks for read this.
Inchae chung

 

[dbailey]

Hi Inchae,

I was away on vacation and am only getting to this now. In the coupled model we rely on the data model components in CDEPS. So, the DATM and DOCN. When you choose the resolution for the atmosphere component like T42 or TL319, this indicates the CORE forcing or JRA atmosphere forcing respectively. We provide these on the native grids and then CDEPS does the interpolation to the appropriate sea ice / ocean grid. So, you can choose TL319_g17 to run the JRA forcing with the gx1v7 dipole sea ice / ocean grid. For the DOCN component, this can run in specified SST or semi-prognostic slab ocean model (SOM) mode. In the SOM mode, this requires a q-flux forcing file (the pop_frc file). Does this answer the question?

Dave

 

[Inchae Chung]

Hi Inchae,

I was away on vacation and am only getting to this now. In the coupled model we rely on the data model components in CDEPS. So, the DATM and DOCN. When you choose the resolution for the atmosphere component like T42 or TL319, this indicates the CORE forcing or JRA atmosphere forcing respectively. We provide these on the native grids and then CDEPS does the interpolation to the appropriate sea ice / ocean grid. So, you can choose TL319_g17 to run the JRA forcing with the gx1v7 dipole sea ice / ocean grid. For the DOCN component, this can run in specified SST or semi-prognostic slab ocean model (SOM) mode. In the SOM mode, this requires a q-flux forcing file (the pop_frc file). Does this answer the question?

Dave

To dave,

Thank you for your reply.

To be more specific, I have a SOM in my system, and I want to restore_SST on it, but when it's a standalone system, I have to set oceanmixed_ice=.true. to work, but I found out that it works only for uncoupled systems.
So, I wonder if restore_SST doesn't work on CICE5+DART (coupled system).
If this is true, my guess is that when CICE5 is an ice-ocean coupled system, it's usually coupled with a POP model, and when someone want to restore SST, someone have to restore it to the POP that's directly related to the ocean component, not to CICE5, so I think the restore_SST option is "only for uncoupled system" because there's no need to restore it to CICE5.

In addition, if I'm right, I understand that the forcing data flows like this.

- In CICE5 (standalone system), atm, ocn forcing data in ice_in are directly involved in the CICE5 model, and are typically used in ice_forcing.F90 and output is generated from it.
- In CICE5+DART (coupled system), unlike CICE5 (standalone system), forcing information is not in ice_in, but in datm_in, docn_in, and these files are indirectly involved in the CICE5 model, and forcing information is reflected. At that time, the path of intervention is through CPL7. However, I wonder if ice_forcing.F90 is used in the coupled system.

I still don't understand how forcing is read and written from xxx_in files from the coupled system such as CESM2 full coupled system.

Thanks for read this.
Inchae Chung

 

[dbailey]

Good questions. I believe your understanding is correct. I have not tried restore_sst when running CICE in CESM. The DOCN-SOM component in CESM computes a prognostic SST. You could override the computation of SST in docn_comp_mod.F90 to acheive this I believe.

Dave