Premerged emission files for 2018_12US1 CMAQ Modeling Platform Data


I’m interested in getting premerged emission files of nonpoint sources for the 2018_12US1 CMAQ Modeling Platform Data. Currently, all nonpoint sources except rwc and biogenic are merged together.

Does anybody know how or where can I get the data from?



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

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 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.

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,

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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?



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

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). 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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The files are added to this folder.

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