# CHEM and AERO processes in Process Analysis for HNO3

**URL:** <https://forum.cmascenter.org/t/chem-and-aero-processes-in-process-analysis-for-hno3/4068>\
**Category:** CMAQ\
**Created:** [April 17, 2023, 7:25am UTC](https://forum.cmascenter.org/t/chem-and-aero-processes-in-process-analysis-for-hno3/4068 "2023-04-17T07:25:31Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![Ben\_Murphy](https://avatars.discourse-cdn.com/v4/letter/b/74df32/32.png) [@Ben\_Murphy](https://forum.cmascenter.org/u/Ben_Murphy)\
**Post date:** [April 18, 2023, 2:42pm UTC](https://forum.cmascenter.org/t/chem-and-aero-processes-in-process-analysis-for-hno3/4068/2 "2023-04-18T14:42:09Z")

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Hi HyeonYeong,

It is good to hear from you. As we discussed for ASO4 ([AERO process in Process Analysis - #2 by Ben\_Murphy](https://forum.cmascenter.org/t/aero-process-in-process-analysis/2868/2)), 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?

Ben

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