ERROR while creating CEMSUM file for the SMOKE

I am trying to create a CEMSUM file for the future year 2026 FROM THE HOURLY CEMS inventory file (example data)

using the following script—

After running it , the following information showed up with the error:

It say’s " ERROR: Could not open input file"

Could you please help me understand why this error occurred?


The filelist should be a list of all of the hourly CEM files to be input into CEM scan. It looks like it is pointing to an hourly FF10.

Hi @eyth.alison

Yes, I have an hourly file which is in FF10 format. I don’t have hourly CEM file.

Can I create CEMSUM file from that FF10 formatted file?

Thanks in advance

You do not need to provide a CEMSUN when you use an hourly FF10 file.

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So, If I use the HOURLY FF10 file, SMOKE does not read the CEMSUM file. Am I right?

If so, Do I need to change the variable name of the file. The default variable name is EMISHOUR_MULTI_A which has Hour_unit file with cemsum in the EPA script

If I use HOURLY FF10 file, Do I need to change variable name to EMISHOUR_A , and comment out the cemsum file? like this:

Thanks in advance

Yes, this is true that CEMSUM will not be read. Here are some suggestions:

The variable name should be changed along with the CEMSUM commented out.

The caveat is that with this method no variables will be temporalized by the heat input in the CEMs because SMOKE currently does not support that method using the hourly FF10 format.

" no variables will be temporalized by the heat input in the CEMs because SMOKE currently does not support that method using the hourly FF10 format"------
Is that an issue if it will not temporalize by the heat input?. Would SMOKE run be correct if I follow this procedure?


SMOKE will use the hourly emissions from your FF10 for any pollutants that are in that file, and will fall back to the “regular temporal profiles” that you provide it for pollutants that are not in that file. Eventually, we will update SMOKE so that you can assign other pollutants to use heat input as a surrogate to base the temporal allocation on, but it is not ready yet. I didn’t check which pollutants are in your flat file to know if the correct behavior is a problem for your analysis.


In my Flat File, I have the following pollutants:

In this case, for those pollutants can I comment out CEMSUM file?

SMOKE would use the hourly values for all of the pollutants in your file and you should not need the CEMSUM for those.

If all hours for the entire year are in one FF10 then you can use just the EMISHOUR variable. Otherwise they can be split into month and the EMISHOUR_MULTI_A variable should be used.

The 2016 platform CMV sectors use hourly FF10s broken up by month with the EMISHOUR_MULTI_A variable set.

The scripts for CMV in 2016v2 platform are a good point of reference for getting the hourly FF10 processing to work.

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