problem with CLM-CN spinup?

[slevis]

I'm posting a problem experienced by a user on Bluefire to see if other users have had a similar experience. We've tried unsuccessfully to uncover something wrong, such as bad atmosphere data or bad initialization. Has this come up for others? If so, have you solved it somehow?

Thank you,
Sam Levis

Message written by clm user:

I did a spinup following the description in chapter 4 in the manual. I use the ICN compset and the same resolution as in the manual. I first ran it for 600 y in accelerated spinup mode, then 1 y in exit spinup and then first 50 y in normal mode, but as it was not in equilibrium, and communications with you and other suggested that longer runs were necessary, I continued for 1350 more years.

The problem is that shortly after the start of the normal run, NPP decreases quickly in tropical areas (reaches zero in less than 10 y, these results are in the CN_finalspinup/lnd/hist folder). In some areas it recovers later in the simulation, but in Amazon it does not, and it ends up with no NPP or carbon in any pool at the end of the simulation. I have not changed anything in the code.

 

[erik]

After looking over the problem this user had, we realized that the directions wrongly have you spinup using a single year of atmospheric forcing. The directions end up having you run over the single year of 2003. With some areas in drought and others flooding you'll wrongly reinforce these patterns by running the spinup over the same year of forcing.

You should modify the years the atmospheric forcing is run over by doing something like this for each case...

./xmlchange -file env_conf.xml -id DATM_CLMNCEP_YR_START -val 1948
./xmlchange -file env_conf.xml -id DATM_CLMNCEP_YR_END -val 2004

The above will have you run over the full range of Quan data forcing from 1948 to 2004. For your application you may want to use a more restricted range of years, depending on what you are trying to accomplish. In general we use 1948-1972 for pre-industrial simulations and 1972-2004 for present day transient simulations.

Also read more about the scientific aspect of spinning the model up by reading the Lawrence et. al. paper at the bottom of the CLM4 documentation page...

http://www.cesm.ucar.edu/models/cesm1.0/clm

 

[devarajun@gmail_com]

Dear Erik,

Thanks for this post.

CLMCN ouput, shortly after the start of the normal run, NPP and SOILC decreases quickly in tropical areas (reaches zero in less than 10 y).

I will run again the spiunp with forcing from 1948-2004.

Thanks again.
Dev

 

[CGL]

Dear Erik,

Thanks for this post.

CLMCN ouput, shortly after the start of the normal run, NPP and SOILC decreases quickly in tropical areas (reaches zero in less than 10 y).

I will run again the spiunp with forcing from 1948-2004.

Thanks again.
Dev

Hi! How can i konw my spinup already balance? I should look up some specific file?

 

[oleson]

1.5.6. Spinning up the Satellite Phenology Model — ctsm CTSM master documentation

1.5.7. Spinup of CTSM1-BGC-Crop — ctsm CTSM master documentation

 

[CGL]

Yes, I find the tools named SpinupStability.ncl, but I can't find it in my_cesm_sandbox folder. By the way, my generated file is monthly file, the SpinupStability.ncl how to manipulate?

 

[slevis]

I don't think that we offer support for this tool, and I believe that ncl is not an active project any more.

 

[slevis]

In any case, the definition of balance or equilibrium is not clear cut, so you will need to think about it yourself to decide what you consider balance in your model simulations.

 

[CGL]

In any case, the definition of balance or equilibrium is not clear cut, so you will need to think about it yourself to decide what you consider balance in your model simulations.

Thanks, I see the meaning.