OC species in CMAQv5.3.2-ISAM

Hi, I’m trying to learn the CMAQv5.3.2-ISAM module. I notice that there are only four OC species (APOCI, APOCJ, APNCOMI, APNCOMJ) could be tracked in this version, however, there were more OC species such as ALVPO1I, ASVPO1I in CMAQv5.3.1-ISAM.

I’m wondering whether it means the latest ISAM version cannot apportion POA accurately now, since the four OC species above only account for a small part of total POA… And does it mean that if I want to do source apportionment for POA, I should go for CMAQv5.3.1?

Thanks a lot!

Dear wangyj18,

Unfortunately, the semivolatile organic components are currently not supported in ISAM. If you would like to have information about POA source attribution, you’re only option is to us the APOC and APNCOM species with their nonvolatile characteristics.

This deficiency will be addressed in the next major release of CMAQ (Fall 2022), but a prototype may be available before then. If you are interested in using such a prototype to proceed with your work and you have a constrained project timeline, we can discuss sharing it with you ahead of the release, with strong caution for the use of code that has not been fully tested of course. This is something we would need to discuss a bit further internally as well.

Best wishes,

Hi Ben,
May I ask whether the SOA source apportionment will be included in the next release of CMAQ-ISAM? As far I know, the ISAM in the current CMAQ only supports the POA source track.


Hi Ryan,

We are working on the prototype and it will be officially available in the next major release (Fall 2022). However, if you are interested in early adopting (and thereby taking on some risk), that’s something we would be happy to discuss.


Hi Ben,
Sure. I would like to get the code and test it based on our California modeling platform. Shall I reach to you by email?

With regards,