[MITgcm-support] Changing cpl_atmSendFrq in Restart Runs of cpl_aim_ocn Configuration

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Dear Community,

I am currently running a simulation based on the cpl_aim_ocn configuration. After completing a 10-year integration, I found that the simulation was quite time-consuming. To improve computational efficiency, I attempted to reduce the coupling frequency by changing the cpl_atmSendFrq parameter in input_atm/data.cpl from 6 hours to 24 hours, so that boundary conditions would be exchanged once per day.

However, when I tried to restart the simulation with this new setting, I encountered the following error in rank_0/Coupler.0000.clog:

CPL_CHECK_CPLCONFIG: Nb of time-steps to run (ATM) = 356400
CPL_CHECK_CPLCONFIG: Nb of time-steps to run (OCN) = 1425600
*** ERROR *** CPL_CHECK_CPLCONFIG: wrong Nb of time-steps to run
*** ERROR *** CPL_CHECK_CPLCONFIG: inconsistent CPL/ATM/OCN config
FATAL ERROR for 1 Proc(s) ==> Stop here

From the error message, I assume this inconsistency is caused by the change in the frequency at which the atmosphere component sends data to the coupler, leading to a mismatch with the ocean component.

I would like to ask:
If I want to change cpl_atmSendFrq, is it necessary to restart the simulation from the beginning with a consistent configuration?
Or is there a way to adjust this parameter mid-run without starting over?

Any guidance on how to handle this would be greatly appreciated.

Best regards,
Fisher
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