Dear Sir/Madam,
I am writing to inquire about the NH4 component of PM2.5 in CMAQ v5.3 simulations.
My simulation domain covers mainland China, and the simulation period is March to April, when dust emissions are relatively high. During this period, my simulation results show an underestimation of NH4. I would like to understand the possible reasons for this underestimation.
The dataset I used for evaluation is TAP. Apart from the uncertainties associated with the TAP dataset and the NH3 emission inventory(MEIC), I would like to know whether the underestimation of NH4 could be considered a systematic bias in CMAQ simulations.
I also noticed that one study mentioned that CMAQ often overestimates non-volatile cations such as Ca, Na. Could this be one of the reasons for the underestimation of NH4? I would also appreciate it if you could share any other possible explanations.
I look forward to your reply.
Best regards,