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geoschem / geos-chem

GEOS-Chem "Science Codebase" repository. Contains GEOS-Chem science routines, run directory generation scripts, and interface code. This repository is used as a submodule within the GCClassic and GCHP wrappers, as well as in other modeling contexts (external ESMs).
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NO2 simulation in GEOS-Chem #2364

Closed helpyuan closed 2 months ago

helpyuan commented 2 months ago

Your name

liumy

Your affiliation

CAMS

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

Hi, all.

I am a beginner in NOx field and I have a confusion about the simulation of NOx in the HEMCO_Config.rc file in GEOS-Chem, which involves the allocation of NO and NO2.

As is well known, NOx=NO+NO2, so my question is as follows:

Does GEOS-Chem consider the rapid conversion of NO in the atmosphere to NO2 through photochemical processes?

If considered, taking the CEDS list as an example, GEOS-Chem converts all NOx in the original CEDS to NO (http://geoschemdata.wustl.edu/ExtData/HEMCO/CEDS/v2024-06/README), without considering NO2. Is this part of NO2 emissions simulated through chemical reactions in GEOS-Chem? Because I did not find the allocation of NO2 by CEDS in the HEMCO_Config.rc file (http://geoschemdata.wustl.edu/ExtData/HEMCO/CEDS/v2024-06/config/HEMCO_Config.rc). image

If not considered, taking the CEDS list as an example, do we need to divide NOx into two parts: NO and NO2, and then allocate NO and NO2 separately in the HEMCO.Config.rc file?

In addition, I have noticed that in some local lists (such as NEI2016, DICE), NO and NO2 are allocated separately, which is different from the CEDS in the HEMCO.Config.rc file. How should this be explained?

Looking forward to receiving your clarification!

yantosca commented 2 months ago

Thanks @helpyuan for writing. GEOS-Chem does account for the fast cycling between NO and NO2 in its mechanism. But GEOS-Chem carries NO and NO2 as separate species.

I believe that the CEDS emissions for NOx were converted to NO (probably by multiplying by the fraction MW(NO) / MW(NOx) because GEOS-Chem does not have NOx species. So we end up putting all the NOx emissions into NO. Probably NO dominates the NOx emissions.

I am not an expert in the CEDS emissions. We recommend reaching out to the Emissions Working Group if you have more questions. Tagging the WG co-chairs: @eamarais @jaegle

yantosca commented 2 months ago

@helpyuan: Also it depends on the inventory. Some inventories report NOx others report NO and NO2 separately.

helpyuan commented 2 months ago

Thanks @yantosca, your explanation has made it clearer for me.

yantosca commented 2 months ago

Thanks @helpyuan. I'll close out this issue now.