How to convert this unit to kg m^-3?

[ChenBHXMU]

Your name

Baihua Chen

Your affiliation

Xiamen University

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

Dear @yantosca

In GEOSChem.SpeciesConc.20190xxxx_0000z.nc4 file, the following is displayed. This file should only contain emission data, not transport, right? Additionally, I also want to know about the marine organic aerosols. But I couldn't find MOPI and MOPO in GEOSChem.SpeciesConc.2019xxxx_0000z.nc4. I find MOPI and MOPO in the HEMCO_diagnostics.2019xxxx0000.nc file, but their units are mod mod-1 dry? How to convert this unit to ng m^-3 or kg m^-3? Just like Figure 2. Moreover, does the GEOS-Chem model not include marine secondary organic aerosol (SOA)?

These questions are very important to me.

Thank you for your help! Have a nice weekend!

Best regard
Baihua Chen

[yantosca]

Thanks for writing @ChenBHXMU and thanks for your patience. We had a long holiday weekend here.

In GEOSChem.SpeciesConc.20190xxxx_0000z.nc4 file, the following is displayed. This file should only contain emission data, not transport, right?

The SpeciesConc collection contains species concentrations, not emissions data.

Additionally, I also want to know about the marine organic aerosols. But I couldn't find MOPI and MOPO in GEOSChem.SpeciesConc.2019xxxx_0000z.nc4. I find MOPI and MOPO in the HEMCO_diagnostics.2019xxxx0000.nc file, but their units are mod mod-1 dry? How to convert this unit to ng m^-3 or kg m^-3? Just like Figure 2.

Did you create a run directory with the marine organic aerosol extra option? If so, your simulation should contain the MOPO and MOPI species in the SpeciesConc collection.

The HEMCO diagnostics file contains emissions in flux units kg/m2/s (mass/area/time), not mol/mol dry.

To convert concentration units (mol/mol dry) to ug/m3 (which I presume is what you want), you can use this conversion:

            # Convert values from ppb to ug/m3:
            # ug/m3 = mol/mol * mol/g air * kg/m3 air * 1e3g/kg
            #         * g/mol spc * 1e6ug/g
            #       = ppb * air density * (spc MW / air MW)

Moreover, does the GEOS-Chem model not include marine secondary organic aerosol (SOA)?

That is correct. The original developers only added MOPO and MOPI primary aerosols but not marine organic SOA.

[ChenBHXMU]

Thanks for writing @ChenBHXMU and thanks for your patience. We had a long holiday weekend here.

In GEOSChem.SpeciesConc.20190xxxx_0000z.nc4 file, the following is displayed. This file should only contain emission data, not transport, right?

The SpeciesConc collection contains species concentrations, not emissions data.

Additionally, I also want to know about the marine organic aerosols. But I couldn't find MOPI and MOPO in GEOSChem.SpeciesConc.2019xxxx_0000z.nc4. I find MOPI and MOPO in the HEMCO_diagnostics.2019xxxx0000.nc file, but their units are mod mod-1 dry? How to convert this unit to ng m^-3 or kg m^-3? Just like Figure 2.

Did you create a run directory with the marine organic aerosol extra option? If so, your simulation should contain the MOPO and MOPI species in the SpeciesConc collection.

The HEMCO diagnostics file contains emissions in flux units kg/m2/s (mass/area/time), not mol/mol dry.

To convert concentration units (mol/mol dry) to ug/m3 (which I presume is what you want), you can use this conversion:

            # Convert values from ppb to ug/m3:
            # ug/m3 = mol/mol * mol/g air * kg/m3 air * 1e3g/kg
            #         * g/mol spc * 1e6ug/g
            #       = ppb * air density * (spc MW / air MW)

Moreover, does the GEOS-Chem model not include marine secondary organic aerosol (SOA)?

That is correct. The original developers only added MOPO and MOPI primary aerosols but not marine organic SOA.

Dear @yantosca

Thank you for your help. I hope you had a great weekend!

I do indeed need to convert concentration units from mol/mol dry to ug/m3. I appreciate the detailed code you provided. May I ask in which file is this part of the code located, and how can I activate this part of the code?

In addition, does the HEMCO_diagnostics.2019xxxx0000.nc file represent emission data, but I am unable to determine which one is MOPO and MOPI within this file?

Best regards
Baihua Chen