why is molecular weight not shown when preparing so4 surface emission inputs

[Yuan Sun]

What version of the code are you using?
CESM2.2.2


Have you made any changes to files in the source tree?
No

Describe every step you took leading up to the problem:
I tried to use CAMS anthropogenic emission data in CESM. In the IPT algorithm IPT/Emissions/CAMS_Anthropogenic/rename_cams_anthro_se.ncl at 56737c4375b76feac0767013c1d2acdf31fea5c1 · NCAR/IPT, ene_ind_so4_surf_out = 0.025*(ene_ind_so2_surf_out)

Describe your problem or question:
I am curious why molecular weight is not shown when converting so2 to so4. In my understanding,
ene_ind_so4_surf_out = 0.025*(ene_ind_so2_surf_out) * (64/115), where molecular_weight of so2 and so4 is 64 and 115, respectively.

Are the molecular weights already integrated within the 0.025 factor?

Thank you for any comments.

Best,
Yuan

 

[rrbuchholz]

Hi Yuan,

A scaling factor is used because emissions units are molecules/cm2/s. So, we are using the parametrization that a 0.025 fraction of SO2 molecules have oxidized to SO4.

You will see the molecular weights are accounted for when calculating particle numbers (e.g. num_ship_so4).

Hope that helps!

Best,
Rebecca

 

[Yuan Sun]

Hi Yuan,

A scaling factor is used because emissions units are molecules/cm2/s. So, we are using the parametrization that a 0.025 fraction of SO2 molecules have oxidized to SO4.

You will see the molecular weights are accounted for when calculating particle numbers (e.g. num_ship_so4).

Hope that helps!

Best,
Rebecca

Thanks, Rebecca, I will check my calculation.

Best,
Yuan