imp_sol: step failed to converge error, FCts2nudged

[Will Smith]

Hi all,

I am having an issue while running the release-CESM2.2.0, with the CAM tag set to cam_cesm2_2_rel_09. My configuration uses the FCts2nudged compset on a resolution of ne30_ne30_mg17. However, during the run, I encountered a imp_sol: step failed to converge error in the cesm.log file. This error appears to be isolated to cesm.log, as other log files do not show any corresponding issues.

Initially, I suspected this might be due to a character length issue, so I made some adjustments below; however, the error persists despite these changes.
from: write(iulog,'('' imp_sol: step failed to converge @ (lchnk,vctrpos,nstep,dt,time) = '',3i8,1p,2g15.7)') &
lchnk,ofl+i-1,nstep,dt(i),interval_done+dt(i)

to: write(iulog,'('' imp_sol: step failed to converge @ (lchnk,vctrpos,nstep,dt,time) = '' &
,3i8,1p,2g15.7)') &
lchnk, ofl+i-1, nstep, dt(i), interval_done+dt(i)

I have attached the log files for your reference. I would greatly appreciate any insights or suggestions you might have on resolving this convergence issue.

Best,
Will

 

[rrbuchholz]

Hi Will,

Could you please also send along the atm.log.* file to double check.

Your error might be related to what is discussed in this post:

Problem running CESM: failed to converge

Hi all, I run CESM2.1.2 on my laboratory computer. I set STOP_OPTION=nsteps, STOP_N=1, but the calculation never stops. cesm.log file says " imp_sol: time step 1800.000 failed to converge @ (lchnk,vctrpos,nstep) = 2616 52 0 imp_sol: time step 1800.000 failed to...

bb.cgd.ucar.edu

Mike Mills discusses potential problems can happen if you make changes in chemistry, or when you are running on a different computer than the one that the initial condition file was generated with.
So, a shorter time step might need to be tried for a couple of days to produce a stable initial condition file.

Best,
Rebecca