CMAQ DESID inquiry

Hi all,
I am reaching out for inquirying the DESID in CMAQv5.4. I am trying to project emissions from 2020 to 2045 for several emission files (Please refer to the DESID file attached and look at Lines after "!> CUSTOM MAPPING EXAMPLES 2020 to 2017 <! "). I would like to know whether I perform the projection correctly because it seems that there are some updates compared to CMAQv5.3.2. The User Guide says that we should use chemical species name rather than compounds name in emission file but the example still use “BENZ” rather than ‘BENZENE’. Could you please confirm whether the User Guide is wrong?
I also attach the CTM_LOG files. From the LOG file, it shows as follows. I wonder if it is normal condition that there are two lines for each chemical species.
EVERYWHERE m 1.188 UNIT 1.188
EVERYWHERE m 1.188 UNIT 1.188
CMAQ_Control_DESID_saprc07tic_ae7i_aq_2035REF.nml.txt (19.8 KB)
CMAQ_Control_Misc.nml.txt (8.7 KB)

Any comments are highly appreciated!

Best regards,

@Ben_Murphy @lizadams

Hi Ryan,

We’ve been messaging privately a bit, but I’ll repeat some of my responses here in case they are helpful to others:

With respect to BENZ vs. BENZENE, it comes down to whether or not you would like to define TOG in terms of the model chemical species, or the emission variables. You can do either, but there will be some consequences.

If you choose to define TOG in terms of emission variables, then make sure you only use the family name in the emission variable field, not the CMAQ model species field (use ‘ALL’ instead). And note that if any of your offline or online streams use BENZENE as the name for the compound instead of BENZ, then the rule will not apply to those cases.

If you choose to define TOG in terms of model species, use BENZENE, and put TOG in the model species field as I suggested above. But then note that the rule will be applied to all emission streams that map emissions to BENZENE, not just ones with the BENZ variable.

Regarding the two-line format you point out above, this is the formatting I ended up using for the log output. In the case of ALK1, it is reporting that first a scaling rule was defined to map ALK1 species to ALK1 emission variable with a 1:1 mapping. Then a second scaling rule, (TOG in your case) was defined that had the effect of multiplying ALK1 by 1.188 everywhere.

As you know from our offline conversation, there are a couple of modifications you could consider to fully apply the mapping from your emissions to saprc model species. I’ll mention for others reading that the log file reports ARO2 emissions are available on each file, but not mapped to any internal species. Meanwhile, ARO2MN and NAPHTHALENE emissions are not found to support mapping to ARO2 and NAPHTHAL, respectively. One solution would be to map ARO2 to AROMN with a factor of 0.96 and AOR2 to NAPHTHAL with 0.04. This is a good example of how the log file can be used to detect issues with the compatibility of the emissions inputs and the default DESID scaling recipe, and correct these issues.



Hi Ben,
Thanks a lot for the detailed clarification which definitely re-shape my understanding of DESID in CMAQv5.4.

Best regards,