About SOA concentration in CMAQ model with cb06

CMAQ Chemistry and Aerosols
1

Hi all,
I am confusing about the secondary organic aerosol concentration in CMAQ model. After using combine to combine all species into the nc file, can I use ASOMIJ to represent secondary organic aerosol concentration with CB06AERO06 mechanism?

Thanks!

2 Likes
2

@cgnolte @Havala.Pye

3

And may I ask what is the isoprene epoxydiols (IEPOX)-derived SOA in CB06-AERO06 mechanism in the combine file?
Please note that the variable for CB06-AERO06 is https://github.com/USEPA/CMAQ/blob/master/CCTM/src/MECHS/cb6r3_ae6_aq/SpecDef_cb6r3_ae6_aq.txt

4

In general, please apply topic tags first, and only tag specific individuals as a last resort.

The SOA treatment in AERO6 is documented here.

5

Hi Chris,
Sorry for forgetting applying tags. I had already found the document you pointed out. But I am still confusing about which variable(s) can be used as SOA concentration in the combine file.
Can I use ASOMIJ to represent secondary organic aerosol concentration with CB06AERO06 mechanism?

Thanks!

6

Which variable you want depends on what your purpose is. ASOMIJ represents the sum of secondary organic mass in the Aitken and accumulation modes, and is probably what you want. For some applications, you might conceivably want PM25_OM instead

7

Hi Chris,
In my understanding, PM25_OM represents the organic matter in PM2.5 which includes primary and secondary organic matter. Thus, I think this can not be used as SOA in general. Am I right?

8

Yes, that’s right. I meant that you could follow the pattern in PM25_OM to compute PM25_SOM.
But again, ASOMIJ is probably what you want.

9

I get it. Thanks for the explanation！It really makes sense to me.
Thanks again!