ERROR: Stopping because of EBI convergence failures in CCTM ISAM

We are running ISAM CCTM with CMAQv5.0.2. for India at a resolution of 36x36 grids for source apportionment. It runs for 8 hr and 12 mins and stops. With the following error.

"ERROR: Max number of EBI time step reductions exceeded
Convergence failure for cell ( 23, 12, 1)
Convergence failure for the following species:

 *** ERROR ABORT in subroutine HRSOLVER on PE 027
 ERROR: Stopping because of EBI convergence failures

ERROR: Stopping because of EBI convergence failures"

The model starts running with 4x7=28 cores in parallal mode and stops.
However, when we run the model with only 1 core, the model keeps working with some high values in AOTHRj in totals but not in SA_ACONC files.

We checked, emission files used are working fine with normal cctm mode but shows up this error when tried out in ISAM.

On checking, we found that values of AOTHRj species (of total and all contributing sectors) go extraordinarily high in the range of E18. The problem starts with the first timestep itself when AOTHRj values go very high and at the 8th hour simulation stops with this error.

The AOTHRJ species is not used in source apportionment at this time. I suggest running your simulation without ISAM and checking the values of this species in the output.

Dear @sumit4879,

Have you resolved this error, please?

Thanks and regards,


Hi Sumit,

I am also getting the same error. Could you remember how you solves that? That would be helpful for me.


Hi Sadia,
Please start a new issue, rather than adding to this one, and provide the version number, run script, log files and other information as suggested here: PLEASE READ before posting
Otherwise it is difficult to know if you are having an issue with CMAQ ISAM, or if you tried Sergey’s suggestion to run your case using CMAQ without ISAM to see if you get the same error, etc.

Thanks for your suggestions.