# Premerged emission files for 2018\_12US1 CMAQ Modeling Platform Data
**URL:** https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325
**Category:** EQUATES
**Tags:** smoke, emissions
**Created:** [August 25, 2023, 4:51pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325 "2023-08-25T16:51:51Z")
**Posts on this page:** 16
**Page:** 1
### Author:  [@huytran6583](https://forum.cmascenter.org/u/huytran6583)
#### Post date: [August 25, 2023, 4:51pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/1 "2023-08-25T16:51:51Z")
Hi,
I’m interested in getting premerged emission files of nonpoint sources for the [2018\_12US1 CMAQ Modeling Platform Data](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/emis/). Currently, all nonpoint sources except rwc and biogenic are [merged together](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/emis/cb6r3_ae6_20200131_MYR/cmaq_ready/merged_nobeis_norwc/).
Does anybody know how or where can I get the data from?
Thanks,
Huy
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### Author:  [@foley.kristen](https://forum.cmascenter.org/u/foley.kristen)
#### Post date: [August 31, 2023, 10:30pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/2 "2023-08-31T22:30:50Z")
Hi Huy,
@lizadams at CMAS copied over the premerged emissions files of nonpoint sources for the 2018\_12US1 evaluation platform. They are available in the same S3 bucket under emis/cb6r3\_ae6\_20200131\_MYR/premerged/nonpt
[https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018\_12US1/emis/cb6r3\_ae6\_20200131\_MYR/premerged/nonpt/](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/emis/cb6r3_ae6_20200131_MYR/premerged/nonpt/)
Note that the files are only created for representative calendar days, not every day of the year.
If you are planning to use make modifications to the nonpt data and then use them in a new simulation you will need to be careful in how you prepare your emissions inputs since the existing gridded merged emissions input files already includes the nonpt emissions. You would need to use a tool such as [combine](https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FUSEPA%2FCMAQ%2Fblob%2Fmain%2FPOST%2Fcombine%2FREADME.md&data=05%7C01%7CFoley.Kristen%40epa.gov%7Cd3ba9c20e59f411a094c08dba02393a7%7C88b378b367484867acf976aacbeca6a7%7C0%7C0%7C638279846892067906%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=CXhGhn4u58ho%2BfQhhfOG%2FihiJuPPySMJWe7QRJ2Xo8A%3D&reserved=0) to subtract the gridded nonpt emissions from the 2018 merged gridded emissions files.
The merged gridded emissions files are for every calendar day so this subtraction process would have to involve matching each calendar day to the appropriate representative day in the nonpt files. The text files with the mapping of representative days to calendar days is available in the emis\_dates folder in the same S3 bucket.
Once you had a new set of merged emissions (e.g., emis\_mole\_all\_2018\*\_12US1\_nobeis\_norwc\_nononpt\_WR413\_MYR\_2019.nc4), then you could use your own nonpt emissions by specifying [a new emissions stream in CMAQ](https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FUSEPA%2FCMAQ%2Fblob%2Fmain%2FDOCS%2FUsers_Guide%2FCMAQ_UG_ch06_model_configuration_options.md%23691-emission-streams&data=05%7C01%7CFoley.Kristen%40epa.gov%7Cd3ba9c20e59f411a094c08dba02393a7%7C88b378b367484867acf976aacbeca6a7%7C0%7C0%7C638279846892067906%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=LD07lDqieiP7y95owcoJ8r0ZGVH9rpF%2BA02LDGEI7cM%3D&reserved=0).
These steps may be very familiar to you already but I wanted to make sure I explained what would be involved with using the files in a new simulation just in case.
Best wishes for your research,
Kristen
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### Author:  [@huytran6583](https://forum.cmascenter.org/u/huytran6583)
#### Post date: [September 14, 2023, 7:25pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/3 "2023-09-14T19:25:59Z")
Hi Kristen,
Thanks for your responses and for sharing the pre-merged nonpoint emission files. I probably was not clear in my original question, but I’m more interested in separate pre-merged files of each sources under nonpoint category (e.g., onroad, nonroad, airports, oil gas, etc.). My immediate interest is in pre-merged files for nonpoint oil and gas sector. Would you be able to share those?
Best,
Huy
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### Author:  [@foley.kristen](https://forum.cmascenter.org/u/foley.kristen)
#### Post date: [September 26, 2023, 8:44pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/4 "2023-09-26T20:44:06Z")
Hi Huy,
First a quick clarification – the categories you list (onroad, nonroad, airports, oil gas) are _not_ included in the nonpt emissions files that we posted earlier. Section 2.1.11 of this paper describes what sources are included in the nonpt category for our 2018 modeling platform: [Redirecting](https://doi.org/10.1016/j.dib.2023.109022)
Per your request, we will add the gridded emissions files for np\_oilgas under the premerged subdirectory for the 2018 cb6r3 emissions ([AWS S3 Explorer](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/emis/cb6r3_ae6_20200131_MYR/)). The pt\_oilgas emissions files are already available under the cmaq\_ready folder.
We are looking into posting all of the gridded emissions files that went into the ‘merged\_nobeis\_norwc’ files for the 2018 modeling platform but this would be further down the road. For your reference the full set of ‘premerged’ gridded emissions include these categories: afdust\_adj, airports, canada\_ag, canadoa\_og2D, livestock, nonpt, nonroad, onroad\_diesel, onroad\_gas, onroad\_ca\_adj\_diesel, onroad\_ca\_adj\_gas, onroad\_can, onroad\_mex, othafdust\_adj, othar, othptdust\_adj, rail, rwc\*.
\*Note residential wood combustion (rwc) emissions are always kept separate from the other gridded emissions so that they can be treated the same way as the other point source fire emissions within CMAQ. This is why they are not included in the ‘merged\_nobeis\_norwc’ files.
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### Author:  [@lizadams](https://forum.cmascenter.org/u/lizadams)
#### Post date: [September 27, 2023, 2:40pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/5 "2023-09-27T14:40:55Z")
The files are added to this folder.
[https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018\_12US1/emis/cb6r3\_ae6\_20200131\_MYR/premerged/np\_oilgas/](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/emis/cb6r3_ae6_20200131_MYR/premerged/np_oilgas/)
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### Author:  [@sqchu](https://forum.cmascenter.org/u/sqchu)
#### Post date: [June 14, 2025, 4:36pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/6 "2025-06-14T16:36:27Z")
Hi Kristen,
In this dataset, I found some species such as POCN and POCP are zero. I`m wondering what species should be used for the OC emission?
Thanks,
Jayden
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### Author:  [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)
#### Post date: [June 14, 2025, 11:56pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/7 "2025-06-14T23:56:33Z")
Hello Jayden,
in the CMAQ aero7 aerosol module, emitted species POC is mapped to model species APOCI and APOCJ and emitted species PNCOM is mapped to model species APNCOMI and APNCOMJ. I don’t recall which premerged emission file(s) contain species POCN and/or POCP and what these species represent, but neither of them are mapped to any CMAQ aerosol species in aero7 so even if they are present in an emissions file, they would not be used by CMAQ.
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### Author:  [@sqchu](https://forum.cmascenter.org/u/sqchu)
#### Post date: [June 19, 2025, 1:27pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/8 "2025-06-19T13:27:39Z")
> [@sqchu](#):
>
> POCN
Hi Christian, thanks for your quick respond!
I am look at the emission data from: [AWS S3 Explorer](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/emis/WR705_2018gc2_cracmmv1/cmaq_ready/). I was trying to use the POC\* species as the primary organic emission, but their values are zero. I am wondering why they are zero, and what species should be used for cracmm module.
Thanks,
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### Author:  [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)
#### Post date: [June 19, 2025, 5:30pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/9 "2025-06-19T17:30:02Z")
Can you clarify which sector(s) have zero POC\* emissions that you are concerned about?
Also, could you please verify whether you are looking at the files in the [cb6r3\_ae6 directory](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/emis/cb6r3_ae6_20200131_MYR/) or the [cracmmv1 directory](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/emis/WR705_2018gc2_cracmmv1/)? All the discussion prior to your first post was about cb6r3 so in my initial response I had assumed that you were asking about POC emissions in those files, but this may have been incorrect. If you are asking about the CRACMM files, you can also look at the DESID control list files in [this directory](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/CMAQ_v54+_cracmm_scripts/) or [this directory](https://cmas-cmaq-modeling-platform-2018.s3.amazonaws.com/index.html#2018_12US1/CMAQ_v55_cracmm2_scripts/) to see how emitted species are mapped to CRACMMv1 or CRACMMv2 model species in this 2018 modeling platform.
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### Author:  [@sqchu](https://forum.cmascenter.org/u/sqchu)
#### Post date: [June 20, 2025, 12:32am UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/10 "2025-06-20T00:32:32Z")
Hi Christian,
Apologize for the cofusion. I didn`t notice that the previsou discussion was about cb6r3. I am talking about the emission for **cracmm** in the directory “WR705\_2018gc2\_cracmmv1”. Should I open a new post for this question?
The POC\* and PNCOM species in all the sectors are zero.
Thanks,
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### Author:  [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)
#### Post date: [June 20, 2025, 12:58am UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/11 "2025-06-20T00:58:08Z")
These 2018 CRACMM emission files were developed for CRACMMv1. In that emissions processing workflow, volatility profiles for primary OM were not applied during SMOKE processing but rather through the CMAQ DESID namelist file when reading these files into CMAQ. Therefore, the only non-zero primary OM emissions in these files are PMOCN2 and PMNCOMN2. “Placeholder” variables for volatility-resolved primary OM emissions (i.e. the POC\* and PNCOM\* variables) were already included in these files, but since all primary OM mass was assigned to PMOCN2 and PMNCOMN2, their emissions are zero. In emission files generated with CRACMMv2 emissions processing workflows (not these 2018 emissions files), volatility profiles are applied during SMOKE processing and POC\* and PNCOM\* are non-zero.
To run CRACMM with these 2018 emission files, the PMOCN2 and PMNCOMN2 species are mapped to the CRACMM model species via the DESID control namelist files. As noted above, DESID namelist files for both CRACMMv1 and CRACMMv2 are included in this modeling platform data package.
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### Author:  [@sqchu](https://forum.cmascenter.org/u/sqchu)
#### Post date: [June 20, 2025, 1:59pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/12 "2025-06-20T13:59:51Z")
Hi Christian,
Thank you so much for the detailed explaination!
Based on my understanding, PMOCN2 and PMNCOMN2 should be used as bulk POA in the model. As for the i and j-mode in the model, I am wondering what is a proper fraction to distribute the PMOCN2 and PMNCOMN2 into the two modes? such as 0.9 for j-mode and 0.1 for i-mode or other ratios that make sense?
In the _CMAQ\_Control\_DESID\_cracmm1\_aq\_2018\_12US1\_CRACMM\_Platform.nml_:
(1) the volatility distribution for the sources of GRIDDED\_GASOLINE and AIRCRAFT are commented. So for some species like AROCN1ALK, should I use the fraction based on the “DIESEL” which is not commented (0.187+0.043=0.23)?
(2) For the species that are only mapped from “POCN2” and “PNCOMN2” (e.g AROCN2ALK), how should I deal with this situation with “POCN2” and “PNCOMN2” being zero?
Thanks,
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### Author:  [@Havala.Pye](https://forum.cmascenter.org/u/Havala.Pye)
#### Post date: [June 20, 2025, 2:24pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/13 "2025-06-20T14:24:13Z")
Hello,
You can use the default I/J assumptions indicated by “FINE” in DESID. Gasoline vehicles should have a volatility distribution different from diesel and I recommend using the gasoline example (uncomment). If you are separating aircraft, those can also use the unique distribution.
The POCN2 and PNCOMN2 species are often not populated but rules were included in DESID just in case. If they are not present in the emission inputs (early CRACMMv1 inputs did not use them), they do not need to be included. The “N2” volatility is often difficult to constrain and is not in all source profiles. If it is “missing”, the mass is likely already accounted for in an “N1” bin.
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### Author:  [@sqchu](https://forum.cmascenter.org/u/sqchu)
#### Post date: [June 20, 2025, 3:28pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/14 "2025-06-20T15:28:21Z")
Hi Pye,
thanks for your quick respond.
(1) I didn`t fine the default I/J assumptions indicated by “FINE” in DESID file. I am a WRF-Chem user, so I am not sure what the default assumption is for CMAQ. Could you please give more info about i/j mode?
(2) For AROCN1ALK, I`ll use the fraction from GRIDDED\_GASOLINE, which is 0.282 of FINE.
(3) For species mapped from POCN2 and PNCOMN2 like AROCN2ALK, it seems that I can just keep them at a very small value near 0.
Thanks,
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### Author:  [@Havala.Pye](https://forum.cmascenter.org/u/Havala.Pye)
#### Post date: [June 20, 2025, 5:32pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/15 "2025-06-20T17:32:45Z")
Hello, You can include “FINE” in the DESID control file. See [CMAQ/DOCS/Users\_Guide/Appendix/CMAQ\_UG\_appendixB\_emissions\_control.md at main · USEPA/CMAQ · GitHub](https://github.com/USEPA/CMAQ/blob/main/DOCS/Users_Guide/Appendix/CMAQ_UG_appendixB_emissions_control.md#b33-aerosol-size-distributions) for how CMAQ knows how to apply size information.
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### Author:  [@sqchu](https://forum.cmascenter.org/u/sqchu)
#### Post date: [June 25, 2025, 12:14pm UTC](https://forum.cmascenter.org/t/premerged-emission-files-for-2018-12us1-cmaq-modeling-platform-data/4325/16 "2025-06-25T12:14:00Z")
Hi Pye,
Thank you so much for the information!