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FAQ: Data ocean slab mode (DOCN-SOM)

Dave,just checking if your reply #19 from november is still valid.What would the best SOM input file be for a 20th century simulation?I see this one ocn/docn7/SOM/pop_frc.1x1d.090130.nc comes from b40.999 but I cannot find info about b40.999.Daniele
 

dbailey

CSEG and Liaisons
Staff member
As I said earlier, we don't have any SOM forcing files derived from 2000 control runs. I would not use pop_frc.1x1d.090130.nc for science runs. This is only there for software engineering test purposes. I would find one that best matches your CAM resolution from the files that are there. Even though they are derived from 1850 control runs, these are better suited for any science questions you are asking.Dave
 
 I am running CAM4 coupled with a slab ocean model (SOM). I simulated the experiment using EGCN compset with f19_g16 resolution.my questions:1) my SOM forcing file is  pop_frc.gx1v6.100105.nc  downloaded from the input data repository. Is this SOM forcing file scientifically right for my experiment ?
2) how many years I need to run to make the model equilibrated, and how could I make sure the model is equilibrated ?

Thank you !
 

dbailey

CSEG and Liaisons
Staff member
There some information about where this SOM forcing file came from if you do ncdump -h on it. Basically it came from years 481-500 of the CCSM4-CAM4 2deg 1850 control run. This is probably fine for your purposes. Generally we find that the SOM runs are equilibrated after 30 years. You can look at global average SST or hemispheric ice volume to see the leveling off in these quantities.Dave
 
Hi, DaveThanks for your answer.I look at the output history files , but I can not find SST variable in the output files . As I know, SST is not default output history fields in CAM. Is this right ?  I get TS (surface temperature) variable in the output history files and I am wondering how TS is calculated over ocean, is TS equal to SST value over ocean ?And I found the same question in : https://bb.cgd.ucar.edu/node/1001327It says the atmosperic energy balance (FSNT-FLNT) in the model should be close to zero for equilibrium. I ran EGCN compset using CESM1.2.0 for about 40 years , but the global average atmosperic energy balance (FSNT-FLNT) can not be zero .I ploted the timeseries of annual/global average atmosphere energy balance(FSNT-FLNT) and surface temperature(TS) and attatched the content. Could you take a look the plot and give me some suggestions ?Thank you !
 

dbailey

CSEG and Liaisons
Staff member
You can add SST to the CICE model namelist with f_sst = 'mxxxx' and it will appear on the CICE history files. I'm not sure how to add it to CAM's history. However, the timeseries of TS is probably sufficient as well. TS is equal to SST over the ocean, and it is the surface temperature of the land or sea ice elsewhere. Something doesn't seem right with your energy balance here. Have you run the atmospheric diagnostics package? Dave
 
Hi, Dave I didn't run the atmospheric diagnostics package. Are there some other ways to find where is wrong in my simulation ?  When I run CAM4 with prescribed climatological SST (10 years simulation), I also have the same problem that atmosperic energy balance  (FSNT-FLNT) is not close to zero ,which is  about -26 W/m2. 
 

dbailey

CSEG and Liaisons
Staff member
I don't understand how you could be getting such a large imbalance. I am bringing in the AMWG liaison on this.Dave
 

hannay

Cecile Hannay
AMWG Liaison
Staff member
If you ran CAM4 with prescribed SSTs, I would expect that FSNT-FLNT would be of teh order of 1 or 2 W/m2 at the most.Here is an example of the AMWG diags with CAM4:http://www.cesm.ucar.edu/experiments/cesm1.0/diagnostics/cam4_diag/f40.1979_amip.track1.1deg.001/f40.1979_amip.track1.1deg.001-obs/It sounds like there is a problem with your setting or your calculation of FSNT-FLNT.   If you run the AMWG diags, it would help to determine whether your problem is into the setting of teh experiemnt or in the post processing of the data.Documentation about AMWG diags are in:
https://www2.cesm.ucar.edu/working-groups/amwg/amwg-diagnostics-package
 
Hi, hanny,I'm running a E1850CN run (the SOM forcing file is pop_frc.b.e11.B1850CN.f09_g16.130418.nc), and the global averaged TS experience too much decrease for the first 40 years, I was wondering if you have encountered similar problems and how to solve it, thanks!Fukai
 

dbailey

CSEG and Liaisons
Staff member
You need to apply for an account on the inputdata server. I cannot email the files to you.Dave
 

hanj@pku_edu_cn

New Member
Hi Dbailey,In ".../models/ocn/docn/tools/pop_som_frc", the file "pop_frc_interp.ncl", which is used to interpolate the data onto a standard 1x1d grid, is not available. I tried to use a NCL command "PopLatLon" to interpolate data by myself, but it did not work with the model. It caused a error as follows:" (lnd_init_mct) :Atmospheric input is from a prognostic model  urban net longwave radiation error: no convergence  clm model is stopping"When I change nothing except for using pop_frc.1x1d.090130.nc in folder ".../pop_som_frc" instead of the one I created, the model works.I guess the problem may be associated with the SOM forcing file. Could you help me solve this problem? Could you update the file "pop_frc_interp.ncl", or provide a 1x1d SOM forcing file of B1850 simulation? I will appreciate that.Look forward to your reply.
Cheers,Jing
 

dbailey

CSEG and Liaisons
Staff member
In the CESM, we require the ocean and sea ice components to run on the same grid. We do not generally recommend interpolating data to a 1x1d grid and then interpolating back to the gx1 (Greenland Pole) grid. Hopefully one of the exisiting datasets in the inputdata directory will work for your gx1 data ocean. The majority of these came from long 1850 control runs with 1-degree atmosphere, ocean, sea ice, and land and represent a well-equilibrated climate. If you have a long fully-coupled control run with the CESM, you can use the tools in pop_som_frc to derive SOM forcing files from the POP ocean model history files. Otherwise you should use something that is reasonably close to the SOM configuration you are using. I don't know your resolution combination, but the file pop_frc.b.e11.B1850C5CN.f09_g16.005.150217.nc is probably the best choice. This comes from the CESM1.2 large ensemble 1850 control run.Dave
 

hanj@pku_edu_cn

New Member
Thanks for your reply.The resolution of my B1850 simulation is T31_g37.Now, I run a E1850CN simulation, using restart files from my B1850 simulation. The thing is about the SOM forcing files.I failed to use the file pop_frc.b.c40.B1850CN.T31_g37.110128.nc but succeed with the file pop_frc.1x1d.090130.nc.The error reported is that X coordinate is not regular and does not increase monotonically. Obviously, gx3v7 is a irregular grid.That is why I try to interpolate data to a 1x1d.So, do you think the file pop_frc.b.e11.B1850C5CN.f09_g16.005.150217.nc will be OK in this case? Appreciate your reply. Cheers,Jing
 

dbailey

CSEG and Liaisons
Staff member
Ok. I believe I understand now. Are you setting up your E1850CN case as T31_g37? The error implies that DOCN is attempting to interpolate from the gx3v7 forcing dataset and it cannot do this. Make sure your namelist for the DOCN component is correct. It might think it needs to interpolate. Also, if your B1850CN case is long enough (100 years or more), you can derive your own SOM forcing from the POP history files of that instead of using that very old gx3v7 case that we have. We do not have a newer SOM forcing file. That is all that I can suggest.Dave
 

hanj@pku_edu_cn

New Member
Thanks, Dave.Please forgive me bother you again and again.I indeed want to create my own SOM forcing file. So, I try to make everything clear. I arrange my questions as follows:  (1) What does the resolution of SOM forcing file indicate? Should the resolution of the SOM forcing be the same as the case's resolution?         I found it seemed not.  I failed to run a T31_g37 simulation with the file "pop_frc.b.c40.B1850CN.T31_g37.110128.nc" where the error was "X coordinate is not regular and does not increase monotonically". However, I can do that with the file "pop_frc.1x1d.090130.nc". Does that mean I must interpolate the T31_g37 forcing file to a 1x1d forcing file?  (2) For conducting a T31_g37 E1850CN simulation, I used a T31_g37 SOM forcing file in place of a default 1x1d by revising the "docn.buildnml.csh" file like that:           $DIN_LOC_ROOT = /glade/p/cesm/cseg/inputdata/           set mod_dompath = $DIN_LOC_ROOT/ocn/docn7           set mod_domfile = domain.ocn.gx3v7.090903.nc           set dat_dompath = $DIN_LOC_ROOT/ocn/docn7/SOM           set dat_domfile = pop_frc.b.c40.B1850CN.T31_g37.110128.nc           set dat_datpath = $DIN_LOC_ROOT/ocn/docn7/SOM           set dat_datfile = pop_frc.b.c40.B1850CN.T31_g37.110128.nc       Are there any problems here? Are there any other files I should revise?  (3) I indeed tried to create my own SOM forcing file, using a NCL command "PopLatLon" to interpolate data to 1x1d. But it did not work with the model. It caused a error as follows:             (lnd_init_mct) :Atmospheric input is from a prognostic model             urban net longwave radiation error: no convergence             clm model is stopping.         I did not interpolate data to T31_g37 because I thought gx3v7 would cause the problem "X coordinate is not regular and does not increase monotonically". So, what are the key points when I create a SOM forcing file?  Appreciate your help. Cheers,Jing
 

dbailey

CSEG and Liaisons
Staff member
The model resolution of T31_g37 is just a short form of T31 atmosphere (CAM) plus gx3v7 ocean and ice. Please see the overall CESM documentation.

http://www.cesm.ucar.edu/models/cesm1.2/
 
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