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Question about the Absence of HONO Production Reaction in the MOZART Gas-Phase Mechanism in WRF-Chem


New member
I've been using WRF-Chem with the chem_opt=201 option for ozone simulations and have noticed an unusual occurrence. The concentration of nitrous acid (HONO) in my simulations is incredibly low, around ×10e-16 ppmv. Upon investigating the gas-phase chemical reactions in the KPP module (specifically CBMZ and RADM2 mechanisms), I found the NO + OH = HONO reaction. However, when examining the MOZART chemical mechanism, this reaction is missing. Is there a specific reason for this omission, or could there be alternative reactions?
I would appreciate any insights or suggestions to help clarify this observation. Your expertise would be valuable.