Change in VOC and PM emissions in DESID namelist

CMAQ
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1

Hi,
I would like to change the emissions of PM2.5, PM10 and VOC for a region using the DESID namelist.
I know how to scale the emissions for simple species (e.g. NH3, NO etc.) but I do not know how to do this for complex species such as PM.
In the user guide, there is kind of example: ```
‘EVERYWHERE’ , ‘ALL’ ,‘PSO4’ ,‘ASO4’ ,‘FINE’,1.0 ,‘UNIT’,‘a’,
‘EVERYWHERE’ , ‘ALL’ ,‘PNH4’ ,‘ANH4’ ,‘FINE’,1.0 ,‘UNIT’,‘a’

Does it mean I should write all PM components individually? Or is there an variable which can gather all PM. I have the same question with VOC.

Regards
Matthieu
2

Hi Matthieu,

Sorry for the delay. If you want to scale all PM components after you’ve added them already, you can use this:

‘EVERYWHERE’ , ‘ALL’ ,‘ALL’ ,‘ALL’ ,‘FINE’, X ,‘UNIT’,‘m’,

to scale the fine-mode components by some factor X. Alternatively if you want to scale coarse PM emissions, you may use:

‘EVERYWHERE’ , ‘ALL’ ,‘ALL’ ,‘ALL’ ,‘COARSE’, X ,‘UNIT’,‘m’,

Be sure to check your log files for the text output of the emission scaling parameters. This is a relatively complicated feature and you’ll want to confirm it is doing what you intend.

Best,
Ben Murphy

3

Thank you very much. I suppose these lines will impact all PM emissions, even natural PM (e.g sea salt). Is there a possibility to limit this change in emissions to only anthropogenic emissions?

4

Yes – for that you would modify the second field, which corresponds to the ‘stream label’ name. See section B.2 of the CMAQ User Guide Appendix, specifically the bullet referring to ‘stream label’. CMAQ/DOCS/Users_Guide/Appendix/CMAQ_UG_appendixB_emissions_control.md at main · USEPA/CMAQ · GitHub

Cheers,
Ben

5

Hi again Matthieu,

With the help of a colleague, I have noticed I did not fully answer your first question. :slight_smile:

For VOC, I recommend defining a chemical family consisting of all the species you would like to scale. Please see sections B.3.5 and B.3.6 in appendix B of the user guide: CMAQ/DOCS/Users_Guide/Appendix/CMAQ_UG_appendixB_emissions_control.md at main · USEPA/CMAQ · GitHub

One issue to remember though, if the members of the VOC chemical family you define have names that you find on the emission input files, then you should put the ‘VOC’ label in the Emission Species field and use ‘ALL’ in the CMAQ-Species field:

‘EVERYWHERE’ , ‘ALL’ ,‘VOC' ,‘ALL’ ,‘GAS’, X ,‘UNIT’,‘m’,

If on the other hand, the names of the VOC family members you set up are consistent with CMAQ species names, then do the reverse:

‘EVERYWHERE’ , ‘ALL’ ,‘ALL' ,‘VOC’ ,‘GAS’, X ,‘UNIT’,‘m’,

Best wishes,
Ben

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