is NO3 as an output in CESM2 WACCM6 aerosol or gas?

[anushree]

Hi all,
I am using CESM2 WACCM6.I am trying to calculate the contribution of different aerosol species to PM2.5.Can i consider NO3 (given in mol/mol which can converted to kg/kg) as aerosol or is it a gaseous species?
Also NH4 as an output (given in mol/mol) is an aerosol right?
If NO3 is a gaseous species how much do i approximate its aerosol contribution to PM2.5?Is there any general rule since its aerosol chemistry is so complex.
Regards,
Anushree

 

[Duseong]

Hi Anushree,

NO3 in the CESM2 output is for gas species NO3 radical. Nitrate aerosol is not included in CESM2 right now, but we are planning to include it in an upcoming CESM version.

Also, you shouldn't use NH4 for aerosol. As far as I know, it was included for nitrogen cycles to be connected to the CLM (anyone please correct me if I am wrong). And I think all aerosols are written in lowercase in CESM.

I think you can't estimate nitrate's contribution to PM2.5 in the CESM2 model, because we don't simulate thermodynamic partitioning of nitrate, so those are not even implicitly included in the PM2.5 in CESM.

But for the ammonium aerosol, because so4_a1,2,3 species have a molecular formula of ammonium bisulfate (NH4HSO4), I think you can multiply the molecular weight ratio of {NH4}/{NH4HSO4} to get the ammonium concentration from so4_a1,2,3 species available in the model.

 

[anushree]

Hi Anushree,

NO3 in the CESM2 output is for gas species NO3 radical. Nitrate aerosol is not included in CESM2 right now, but we are planning to include it in an upcoming CESM version.

Also, you shouldn't use NH4 for aerosol. As far as I know, it was included for nitrogen cycles to be connected to the CLM (anyone please correct me if I am wrong). And I think all aerosols are written in lowercase in CESM.

I think you can't estimate nitrate's contribution to PM2.5 in the CESM2 model, because we don't simulate thermodynamic partitioning of nitrate, so those are not even implicitly included in the PM2.5 in CESM.

But for the ammonium aerosol, because so4_a1,2,3 species have a molecular formula of ammonium bisulfate (NH4HSO4), I think you can multiply the molecular weight ratio of {NH4}/{NH4HSO4} to get the ammonium concentration from so4_a1,2,3 species available in the model.

Thank you so much for this answer! I really did not know this.

 

[Hemraj]

Hi Anushree,

NO3 in the CESM2 output is for gas species NO3 radical. Nitrate aerosol is not included in CESM2 right now, but we are planning to include it in an upcoming CESM version.

Also, you shouldn't use NH4 for aerosol. As far as I know, it was included for nitrogen cycles to be connected to the CLM (anyone please correct me if I am wrong). And I think all aerosols are written in lowercase in CESM.

I think you can't estimate nitrate's contribution to PM2.5 in the CESM2 model, because we don't simulate thermodynamic partitioning of nitrate, so those are not even implicitly included in the PM2.5 in CESM.

But for the ammonium aerosol, because so4_a1,2,3 species have a molecular formula of ammonium bisulfate (NH4HSO4), I think you can multiply the molecular weight ratio of {NH4}/{NH4HSO4} to get the ammonium concentration from so4_a1,2,3 species available in the model.

Hi @Duseong

I was also coming across the same question discussed above. There is also NH4NO3 (kg/kg) as the model output. Since the CESM model output has NH4 and NO3 in mol/mol, can I do the following calculation to compare model results with observation for NH4 and NO3? Just wonder if it is the right approach?

NH4 = NH4NO3 * 18.04 / 80.04
NO3 = NH4NO3 * 62 / 80.04