I don’t know if direct traffic emissions(HONO=0.8%*[NOx]) are considered in the CMAQ mechanism and I can’t find the relevant files in BLD_CCTM_v531_intel. Thank you for your help!
You would have to know the details of how the traffic emission inputs were built and (potentially) merged with other area emission sources for input to CMAQ. Typically traffic inputs for the US do include HONO, but I’m not sure if the magnitude fits the parameterization you have suggested.
If you do not have a HONO species available on your emissions inputs, then you can add emissions for HONO explicitly using DESID (CMAQ/CMAQ_UG_tutorial_emissions.md at main · USEPA/CMAQ · GitHub) but of course you will need traffic emissions in their own input file in order to limit the scope of the rule to just traffic.
Thanks so much for your kind suggestion and I’ll try to use DESID.