# Output CO2 or aerosol concentrations & optical depth

**URL:** <https://forum.ecmwf.int/t/output-co2-or-aerosol-concentrations-optical-depth/12176>\
**Category:** OpenIFS\
**Tags:** openifs-43r3, openifs-climate-data, openifs-aerosol-processes, openifs-physics-parametrizations\
**Created:** [30 March 2023 14:27 UTC](https://forum.ecmwf.int/t/output-co2-or-aerosol-concentrations-optical-depth/12176 "2023-03-30T14:27:23Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Joakim\_Kjellsson](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/j/e19b73/32.png) [@Joakim\_Kjellsson](https://forum.ecmwf.int/u/Joakim_Kjellsson)\
**Post date:** [30 March 2023 14:27 UTC](https://forum.ecmwf.int/t/output-co2-or-aerosol-concentrations-optical-depth/12176/1 "2023-03-30T14:27:23Z")

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Good afternoon

I'm using OpenIFS 43r3v2 and I'd like to be able to output concentrations of greenhouse gases and aerosols. It would also be great to output aerosol optical depth for a few spectral bands.

I went into yomxios.F90 and added "aod550" (GRIB code 210207, [https://codes.ecmwf.int/grib/param-db/?id=210207](https://codes.ecmwf.int/grib/param-db/?id=210207)) and added this to my field\_def and file\_def xml files for XIOS. I got a field "aod550" in my output files, but its filled with zeros everywhere, so I'm guessing this is not actually the optical depth in the model.   
  
 Which GRIB codes and field names would be the ones containing the aerosol and GHG concentrations etc?   
 Is there a way to add these fields to output for XIOS?

Many thanks  
 Joakim

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**Author:** ![Etienne\_Tourigny](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/e/50afbb/32.png) [@Etienne\_Tourigny](https://forum.ecmwf.int/u/Etienne_Tourigny)\
**Post date:** [30 March 2023 17:09 UTC](https://forum.ecmwf.int/t/output-co2-or-aerosol-concentrations-optical-depth/12176/2 "2023-03-30T17:09:06Z")

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The&nbsp; "concentrations of greenhouse gases and aerosols" cannot be output directly at grid-point level if you don't enable this as a tracer with some initial values and add tendencies. I think you are looking for something much more simpler and enabling the output of these values gives you 0 because this is not what it was designed for.