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WRF-Chem produce extremely low NH3 gas when using chem_opt=132 (cb05_sorg_vbs_aq_kpp)


New member

I am using WRF-Chem v3.7.1 to look at the gas concentrations during Mar 2022. The model with chem_opt=132 produced very low NH3 gas concentration whic is obviously wrong. However, the resutls from some other options (e.g. chem_opt=131) makes more sense in terms of the magnitude and pattern. I am wondering if anyone has this issue?

Many thanks in advance.

Hi, this is likely related to the thermodynamics solver and the inclusion of SO2 heterogenous chemistry in the mechanism for 132.

Two options, 1) change the value of isorop to be equal to 0 in module_aerosols_sorgam_vbs.F so that eql4 is called instead of eql3. 2) Add a comment in front of the KPP .eqn file for mechansim 132 such that SO2 heterogenous chemistry is not called. In both cases, perform a ./clean -a and recompile.