FAQ: Data ocean slab mode (DOCN-SOM)

[dbailey]

Boundary layer depth (turbulent mixing based) seemed more physical than an arbitrary depth based on the density or temperature gradient.

 

[michelle_dvorak]

Hi Dave, thanks for your help so far. Like some others I have a question about achieving a stable equilibrium ocean temperature in a SOM setup. I am runing an 1850_CAM60_CLM50%SP_CICE_DOCN%SOM_MOSART_SGLC_SWAV compset with CESM2.1.3, and using the
pop_frc.b.e21.B1850.f09_g17.CMIP6-piControl.001_branch2.012120.nc forcing file from the inputdata directory.

After 30 years of simulation I'm still getting a steady warming (about 0.05 degrees C per year in global average SST). I'm wondering:
a) If I just need a longer spinup time to reach a steady state
b) If there is a mismatch between my configuration and the configuration that the forcing file is derived from
c) If it would be appropriate to apply a global offset to the forcing file to attempt to compensate for the energy imbalance

Any advice you have would be very helpful, thanks!

I'm curious about this. I've been using the same forcing files in my simulations -- with some local modifications.

Do we know if pop_frc.b.e21.B1850.f09_g17.CMIP6-piControl.001_branch2.012120.nc is the best option for a CESM2 preindustrial control slab ocean run?

A TOA imbalance of 0.15 Wm-2 does not seem negligible.

Michelle

 

[dbailey]

This one is from a retuned sea ice albedo run (Kay et al. 2022). So, it might be off because you are using the out of the box sea ice tuning. I would recommend setting the following in user_nl_cice:

r_snw = 1.50
dt_mlt = 1.00

This might help with the TOA a bit. After how many years did you evaluate the TOA? Might have to run at least 30 years before it starts to come down.

 

[michelle_dvorak]

This one is from a retuned sea ice albedo run (Kay et al. 2022). So, it might be off because you are using the out of the box sea ice tuning. I would recommend setting the following in user_nl_cice:

r_snw = 1.50
dt_mlt = 1.00

This might help with the TOA a bit. After how many years did you evaluate the TOA? Might have to run at least 30 years before it starts to come down.

I am not sure how many years this is from -- I am quoting this from Will Kranz's earlier post.

Given that I've already run experimental simulations with this Qflx file without that sea ice change, I wonder if it's sufficient to run a new PI with this Qflx file but also without the sea ice parameter change, to correct for this bias? Or would you suggest re-running the experimental simulations with a different (CMIP6 PI) Qflx file?

 

[dbailey]

I'm not sure we have another Qflx file that would suit your needs here. You are welcome to continue running the experiment you have to see if the TOA bias comes down more? I should note that we not consider a TOA imbalance of 0.2 or less to be "small enough".

 

[Sreerag]

Hi,
I am running CESM2.1.2 with slab ocean aquaplanet simulation (Qflx is zero) with the seasonal cycle. I am encountering an asymmetry in the north-south SOLIN with a value of 0.74w/m^2 increase in the southern hemisphere. This is very similar to this queries North ITCZ. I have used different compiler gcc/7.5m,gcc/9 and gcc/12 to compile the model all of them gives exactly same asymmetry. I also tried with cesm 2.1.0. Does anyone have a comment on this please let me know?

The changes I done are :
./create_newcase --case Testing_SOLIN_intel --compset QSC6 --res f19_f19_mg17 --compiler intel --mpilib impi

I introduced seasonality by including orbital parameters in user_nl_cpl:
orb_eccen = 0.
orb_obliq = 23.5
orb_mvelp = 0.
orb_mode = "fixed_parameters"

And commented these two lines in the following block in seq_infodata_mod.F90 file and put it into SourceMods/src.drv/:

if ( infodata%aqua_planet ) then
infodata%aqua_planet_sst = 1
!infodata%perpetual = .true.
!infodata%perpetual_ymd = aqua_perpetual_ymd
endif
For sanity check. I made the obliquity to -23.5 which make the asymmetry 0.74w/m^2 increase to northern hemisphere.

If anyone has encountered this issue, any suggestions or resolutions would be greatly appreciated.