CMAQ v5.5.3 Process Analysis: IPR Emission Issue

CMAQ
1

Hi everyone,

I’m currently working on process analysis in CMAQ v5.5.3, specifically analyzing nitrate formation using the IPR module. During my calculations, I observed that the EMIS-ANO3 (contribution of emissions to nitrate concentration) seems disproportionately high, especially considering that nitrate is predominantly formed through secondary processes.

For reference, I’m conducting the simulation for a site in Beijing (layer 1), and my calculation setup is as follows:

DEFINE FAMILY ANO3 = ANO3J + ANO3I;
IPR_OUTPUT ANO3 = EMIS+HADV+HDIF+VDIF+ZADV+DDEP+AERO+CHEM+CLDS;

I’m concerned that the EMIS_ANO3 contribution is overestimated compared to the literature. Has anyone experienced similar issues with this version of CMAQ, or could there be something wrong with my setup?

I would appreciate any feedback or guidance on resolving this discrepancy.

Thank you for your help!

Best regards,
Zhenze Liu

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2

I assume you mean CMAQv5.3.3.
This is not directly related to your question, but note there were updates to process analysis in v5.4: the release of the budget tool, and inclusion of organic vapors in the aerosol condensation process.

You might turn on the DESID emissions diagnostic file, creating a single 2d column-sum output file containing total emissions across all emissions streams. You could then compare the modeled emissions in the diagnostic file to the process analysis calculation of the emissions process, and see whether there is a discrepancy.

In v5.3.3., I believe the way to achieve this is:
setenv EMISDIAG 2DSUM
setenv EMISDIAG_SUM T

2 Likes
3

Thanks for the advice. I’ll give it a try.