Questions about "hybrid" and "RUN_REFDATE"

[yugong]

Hello everyone, I am new to CESM. I have learned a lot from this forum, but I still have some questions about "hybrid" and "RUN_REFDATE".

When i create a new case with ./create_newcase --case B1850 --compset B1850 --res f09_g17, and then ./xmlquery RUN_REFTYPE
I expected it to return "startup", since it's a new case. But it returns "hybrid", which really confuesd me.

After further check, i found this new case has a RUN_REFCASE: b.e21.B1850.f09_g17.CMIP6-piControl.001_v3hist

1. So my first question is: Does B1850 is actually created based on another case? Under what conditions can one create a "startup" case?

2. my second question is that i found REFDATE=0134-01-01, what does it mean? Does it indicate that the case has run for 134 years, and B1850 was created using the output from the 134th year? Additionally, RUN_STARTDATE=0001-01-01, what does it mean? why it is not 1850-01-01? What would happen if I executed ./xmlchange RUN_STARTDATE=1850-01-01

3. I know CESM2 Component Sets Definition gives a very brief description about compsets. Is there some ways i can know more details of each compset?

Could anyone provide some answers? Thank you very much!

 

[slevis]

I answered the same question here:

Questions about hybrid and RUN_REFDATE

Hello everyone, I am new to CESM. I have learned a lot from this forum, but I still have some questions about "hybrid" and "RUN_REFDATE". When i create a new case with ./create_newcase --case B1850 --compset B1850 --res f09_g17, and then ./xmlquery RUN_REFTYPE I expected it to return "startup"...

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