WRF uses continuous “accumulated precipitation” variables RAINC and RAINNC, in mm. CMAQ requires precipitation during the time step (typically 1 hour). MCIP performs this calculation. The version of MCIP I was using at that time had a bug in the way it handled WRF’s “tipping bucket”. As a result, the MCIP output indicated that over 1 meter of rain fell in a single hour. This led to AQCHEM taking too small of an internal time step, with the result that it did not converge in the allotted number of iterations.
Check your MCIP precipitation variables. Are there any unreasonably large (over 1 meter) values?
If so, rerun using an updated version of MCIP – this bug was corrected years ago.
If not, please read the “READ ME FIRST: getting started” post, then post your message in a new thread.