CHEM and AERO processes in Process Analysis for HNO3

Hi, all!

I have some questions about process analysis for HNO3 production and loss.

I did a simulation for HNO3 and particulate nitrate concentration using CMAQ v5.3.1,
I detected that values of AERO process of HNO3 were not to zero, and also positive or negative.

So my question is, if AERO process of HNO3 is positive, it means larger HNO3 production from heterogeneous reaction of N2O5 than HNO3 loss for aerosol production such as particulate nitrate?

Also, if AERO process of HNO3 includes heterogeneous HNO3 production from N2O5, CHEM process only includes gas-phase chemical reactions producing HNO3??

I hope I can get any responses for my questions.

Thank you.

HyeonYeong Park

Hi HyeonYeong,

It is good to hear from you. As we discussed for ASO4 (AERO process in Process Analysis - #2 by Ben_Murphy), I would not trust CMAQv5.3.1 for aerosol process analysis. I recommend updating your model, preferably to v5.4.

Were you able to solve the issue of negative values for ASO4I?


Thanks to your response and recommendation.

I’m still getting negative values for total sulfate.
Although, I didn’t analyze AERO process for only ASO4I, I think there may be also negative values in AERO process for ASO4I, because if aitken mode sulfate grows up to be accumulation or coarse mode sulfate particle, then aitken mode sulfate particle should be decreased.

When I posted issues of negative values for sulfate, I was not familiar with process analysis technique. And thanks to your reminder of the post.

Also, I discovered that heterogeneous N2O5 reaction affected the CHEM process of nitric acid in CMAQ version 5.3.1.
It means CHEM process includes HNO3 formation from heterogeneous N2O5 reaction.

In CMAQ version 5.4, Does the CHEM process of nitric acid include heterogeneous N2O5 reaction to form nitric acid??