emissions to concentrations Q (unit_conversions.jl)

[declann]

Hi guys!

Really like toying with ClimateMARGO and the informative notebooks and learning about a simple but useful climate model! Great work 🥳
Will like to release a simple climate model also, or recreate MARGO or do some exercises with it in a modelling langage (calculang) I develop - will reach out if I get results!

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In my model I got stuck on method/assumptions to convert emissions to concentrations. I can see how MARGO does this in unit_conversions.jl:

const year = 365.25 * 24. * 60. * 60.

GtCO2_to_ppm(GtCO2) = GtCO2 / (2.13 * (44. /12.))
tCO2_to_ppm(tCO2) = GtCO2_to_ppm(tCO2) * 1.e-9

ppm_to_GtCO2(ppm) = ppm * (2.13 * (44. /12.))
ppm_to_tCO2(ppm) = ppm_to_GtCO2(ppm) * 1.e9

Can you please provide any info or sources for the parameters/approach used here? (i.e. factor 2.13 * (44. /12.)~=7.81)

Thanks!
Declan

[hdrake]

Hi @declann, that's great! Multiplying by 2.13 converts from parts per million CO2 to Gigatonnes of carbon and then multiplying by 44/12 gets us back to mass of CO2 (12u + 2*16u = 44u compared to 12u for just elementary carbon).

[declann]

Perfect, exactly what I needed, thanks very much Henri !