Thanks @jbash. When using NH3-bidi in CMAQv5.3.2, is it OK to have NaN values for the variables ‘NH3’ and ‘NH3_Emis’ but not ‘NH3_Flux’ in the CCTM_DRYDEP_* output file? I have more info with plots at the post NaN values of NH3_Emis variable in CCTM_DRYDEP_* file regarding this issue.