About setting MEGAN in HEMCO_Config.rc file

[yangning-code]

Your name

Ning Yang

Your affiliation

JNU

Please provide a clear and concise description of your question or discussion topic.

I am using GEOS-Chem to simulate pollutants for 2023, but I want to use the online MEGAN emissions for 2013. How should I set it up to achieve this?

[msulprizio]

Hi @yangning-code. You can simply set the following in HEMCO_Config.rc:

--> OFFLINE_BIOGENICVOC    : false

and

108     MEGAN              : on

If you would like to utilize the biogenic emissions output diagnostic, you will also need to modify all Biogenic entries in HEMCO_Diagn.rc to use ExtNr Cat of 108 -1 (to get the field from the MEGAN extention 108) instead of 0 4 (to get the field from the base emissions).

[yangning-code]

Thank you very much. You may have misunderstood what I meant. What I meant was that I am now simulating pollutants for 2023, and the online emission MEGAN also uses 2023, but now I just want to change MEGAN to 2013 emissions. I don’t know how to set up the online MEGAN emissions so that when I run 2023, the MEGAN list for 2013 is called.

[msulprizio]

@yangning-code HEMCO extensions will use the meteorology for the simulation dates.

One way to use 2013 MEGAN emissions is to run your simulation for 2013, keeping in mind that GEOS-Chem will also use 2013 meteorology for the other operations (transport, etc.). If using that method, you can set Emission Year in the settings section of HEMCO_Config.rc to 2023 for the base emissions inventories.

If you wish to simulate GEOS-Chem with 2023 meteorology, all other emissions with 2023 (or latest year available), and only change MEGAN to use 2013 emissions, then you may want to consider running the HEMCO standalone for 2013 and saving out 2013 MEGAN emissions via the HEMCO diagnostics. You can then update HEMCO_Config.rc to read those fields (in a similar manner to what is done for the offline biogenic VOC emissions).

[yangning-code]

Thank you very much