About SOA species in CMAQ v5.3

CMAQ Chemistry and Aerosols
1

Hi, all,

I’m trying to calculate simulated POA and SOA concentration resulted from CMAQ version 5.3 using AERO7 mechanism.

But I’m confusing whether ‘ALVOO1, ALVOO2, ASVOO1, ASVOO2, ASVOO3’ should be treated as SOA or not since they are oxidation product of POA species and defined as POA in ‘AE_cb6r3_ae7_aq.nml’ file but also Murphy et al. (2017).

However, there is ‘SpecDef’ file representing the calculation of ‘ASOMI’, ‘ASOMJ’ including those oxidation product of POA.

Thus, my question is those oxidation product of POA species should be treated as POA?? or SOA??

I hope I can get any answer as soon as possible.

Thank you.

HyeonYeong Park

2

Hi HyeonYeong,

Typically we assume that the species you listed are treated as SOA since they are oxygenated and would presumably be detected by an AMS as OOA and lumped with the SOA mass in an analysis like that.

However, it is an ongoing debate whether or not to treat oxidized POA as SOA or not. If you like, you can try both ways to see what makes sense with the measurements you are comparing to. My default would be to assume they are SOA though.

Best wishes,
Ben

2 Likes
4

Dear Dr. Murphy

Thanks to your kind response! :slight_smile:
It really helped to understand CMAQ SOA species well.

Thank you again :slight_smile:

Best regards,
HyeonYeong Park

5

Dear Dr. Murphy

Thank you for your helpful response on the forum regarding SOA representation in CMAQ outputs. I have a follow-up question and would really appreciate your insights.

I’m working with CMAQv5.3 and trying to determine the most appropriate way to represent SOA in my analysis. Should I use ASOMIJ as the primary SOA tracer, or should I calculate SOA based on the species listed under SAO_ACCUM in the AE_cb6r3_ae7_aq.nml file?

Thanks again for your time and guidance!

Best regards,
Mengxin

6

Hi Mengxin,

The most representative calculation for SOA would be to use the ASOMIJ species from the post-processing SpecDef file.

Cheers,
Ben

1 Like
7

Dear Dr. Murphy,

Thank you for your helpful response regarding the representation of SOA in CMAQ outputs. Your guidance on using ASOMIJ as the primary SOA tracer was very useful.

I have another question related to the combined output files from CMAQ. Specifically, I would like to clarify the meanings of the variables AORGAJ, AORJBJ, and AORJCJ in the output files. Additionally, I would like to ask:

  1. Is AORJAJ an appropriate tracer for anthropogenic secondary organic aerosol (ASOA)?

  2. Is AORJBJ an appropriate tracer for biogenic secondary organic aerosol (BSOA)?

  3. Which variable would be most suitable for representing primary organic aerosol (POA)?

Your insights on these questions would be greatly appreciated as they are critical for accurately interpreting the model results in my analysis.

Thank you again for your time and expertise. I look forward to your response.

Best regards,
Mengxin

8

Hi Mengxin,

  1. Yes, AORGAJ is all anthropogenic organic aerosol.
  2. Yes, AORGBJ is all biogenic organic aerosol.
  3. For POA, use the recipe for APOMIJ from the SpecDef file.

The SpecDef file for CMAQv5.3 and cb6r3 is here: CMAQ/CCTM/src/MECHS/cb6r3_ae7_aq/SpecDef_cb6r3_ae7_aq.txt at 5.3.3 · USEPA/CMAQ · GitHub

Good luck,
Ben

1 Like
9

Dear Dr. Murphy,

Thank you very much for your clear and helpful response regarding the variables in the CMAQ output files. Your explanations have been extremely valuable for my understanding of the model outputs.

The detailed information you shared, particularly the link to the SpecDef file, will be instrumental in accurately interpreting the model results for my analysis.

Thank you again for your time and expertise. I greatly appreciate your support.

Best regards,

Mengxin