Run type questions

[ganbaranaito]

Hello everyone,

Recently, I wanted to use compset 'B1850' to do some ideal experiments but some sets confused me.

1. If compset is set by 'B1850', what are the differences between RUN_TYPE 'startup' and 'hybrid'? Does 'hybrid' have no spin-up time?
2. If I use compset 'B1850', 'RUN_TYPE' will be set by 'hybrid' by default. And 'RUN_REFCASE' will also be set by default. However, some different 'RUN_REFDATA' can be chosen. What are the differences between different 'RUN_REFDATE'? How can I choose appropriate 'RUN_REFDATE'?

Any suggestions are welcome. Thanks!

 

[ganbaranaito]

3. And which 'RUN_TYPE' or 'RUN_REFCASE' is the common practice to initial a new experiment by using compset 'B1850' ? Thanks.

 

[mlevy]

Have you seen the CIME documentation on how to run a case? This page may be helpful - it details the differences between startup, hybrid, and branch runs. If that doesn't clear it up, let me know and I can try to give a better summary.

 

[ganbaranaito]

Have you seen the CIME documentation on how to run a case? This page may be helpful - it details the differences between startup, hybrid, and branch runs. If that doesn't clear it up, let me know and I can try to give a better summary.

Hi, Michael.
Thank you for your reply. Yes, I have seen that. But some questions still confused me.

1 If I choose 'startup' runs, all components are initialized using baseline states. What do 'baseline states' mean? Which initial files are used by default setting in a 'startup' run? Can I decide the initial files in a 'startup' run?

2 In 'startup' runs, if I set values on $RUN_REFDIR and $RUN_REFCASE, do these variabilities work? Do the model use these files?

3 As I know, 'startup' run has a long spin-up time. And I want to choose 'startup' to do some ideal experiments. If I want to integrate a 'startup' run for 100yrs, is it enough to get quasi-equilibrated climate state?

I'm so sorry for raising many questions, but they are very important to me. Thanks!

 

[jedwards]

1. The default files are set according to the selected compset, you can override these settings with specific files using the user_nl_* mechanisim to specify the initial files you desire.
2. In a startup run these variables are ignored.
3. It really depends on the case you are trying to spinup. The process of reaching an equilibrium state is an active area of science research, running for a long spinup period is only one approach and may not be the best one for your application.

 

[ganbaranaito]

1. The default files are set according to the selected compset, you can override these settings with specific files using the user_nl_* mechanisim to specify the initial files you desire.
2. In a startup run these variables are ignored.
3. It really depends on the case you are trying to spinup. The process of reaching an equilibrium state is an active area of science research, running for a long spinup period is only one approach and may not be the best one for your application.

Thank you for reply! It helps me a lot! And about question 3, if I want to use B1850 to do some experiments to research the variability of the AMOC, is it suitable to choose 'startup' as runtype?

 

[nanr]

Thank you for reply! It helps me a lot! And about question 3, if I want to use B1850 to do some experiments to research the variability of the AMOC, is it suitable to choose 'startup' as runtype?

You want to retain the default 'hybrid' setting for an B1850 control simulation to test AMOC. That will start all component models from a consistent state in the validated CESM2 pi control. A 'startup' run will start the ocean from observations (Levitus) instead of a spun-up state.

 

[ganbaranaito]

You want to retain the default 'hybrid' setting for an B1850 control simulation to test AMOC. That will start all component models from a consistent state in the validated CESM2 pi control. A 'startup' run will start the ocean from observations (Levitus) instead of a spun-up state.

Thank you for your advice! I think I should choose 'hybrid' to do my experiment!