Add new aerosol particles and turn off their chemical reaction

Hello! I generated a coarse aerosol emission file in nc format, which needs to be added to the CMAQ model to simulate its transport and sedimentation process, but the particles do not need to participate in the chemical reaction process. How can I add new aerosol species to the model and turn off the chemical reaction process of gas and aerosol? Thanks!


It is not really clear what you have done already and what you are trying to do. If you added a new aerosol species, it wouldn’t participate in any chemistry automatically. Could you, please, clarify what you are asking?



Since you only want to simulate the transport and sedimentation without any chemical reaction process, you may consider adding chemically inert tracers to CMAQ Inert tracer tutorial. Hope this can help you.


Unfortunately there is not a simple option (e.g. via environment variable) to turn off chemistry in modern CMAQ versions. Historically, there have been compilation options to choose modules that make no modifications to the concentration field, so-called ‘no-op’ options. These are still present to some degree in the current source code, but they are untested.

I recommend finding emission inputs for gas and aerosol species that will allow you to run with chemistry on. If you would like to comment out the call to chemistry in the sciproc.F source code file, you may try this at your own risk.

Best wishes and good luck,

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