Derivation of atmospheric reaction mechanisms for volatile organic compounds by the SAPRC mechanism generation system (MechGen)

Carter, William P. L.; Jiang, Jia; Orlando, John J.; Barsanti, Kelley C.

doi:https://doi.org/10.5194/acp-25-199-2025

Articles | Volume 25, issue 1

https://doi.org/10.5194/acp-25-199-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-25-199-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 25, issue 1

Research article

|

08 Jan 2025

Research article |

| 08 Jan 2025

Derivation of atmospheric reaction mechanisms for volatile organic compounds by the SAPRC mechanism generation system (MechGen)

William P. L. Carter, Jia Jiang, John J. Orlando, and Kelley C. Barsanti

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Final revised paper (published on 08 Jan 2025)
Supplement to the final revised paper
Preprint (discussion started on 03 Nov 2023)
Supplement to the preprint

Interactive discussion

Status: closed

RC1: 'Comment on egusphere-2023-2343', Luc Vereecken, 07 Dec 2023

The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2343/egusphere-2023-2343-RC1-supplement.pdf

Citation: https://doi.org/10.5194/egusphere-2023-2343-RC1
CC1: 'Comment on egusphere-2023-2343', Tim Wallington, 13 Feb 2024

The SAPRC mechanism has played a key role in atmospheric chemistry research and the development of policies to improve urban air quality since publication of the first version (SAPRC-90) in 1990. MechGen is a mechanism generation system which has been used to construct chemical schemes and estimate the rates of gas-phase chemical reactions and photolysis processes in the development of SAPRC mechanisms since 1999. This paper provides detailed documentation of the chemical basis of the version of MechGen which was used to construct the latest version of the SAPRC mechanism (SAPRC-22). The documentation is comprehensive and is presented in a clear and logical order. This is the first comprehensive peer-reviewed report describing MechGen and its publication will facilitate broader use of MechGen. It will be an important reference source both for the chemistry in MechGen and more broadly for the current state of atmospheric chemistry.

Citation: https://doi.org/10.5194/egusphere-2023-2343-CC1
RC2:
'Comment on egusphere-2023-2343', Anonymous Referee #2, 11 Apr 2024
As a key part of chemical transport modeling, gas phase mechanism is crucial in determining formation of secondary components, including both gases and particulate matter. However, there are no summarizing documents in recently years and many modelers are not familiar with the details. As the most detailed documentation of the SAPRC mechanism, I welcome its publication. Please find below comments for improving the manuscript.
The abstract just shows what are included in the manuscript, with key messages to give.

MechGen is the key program, however, this manuscript does not provide its basic idea, processes, and structure. The code of MechGen is also not provided.

The writing is too much like a report instead of scientific article, I would like to see more references to the statements.
Citation: https://doi.org/10.5194/egusphere-2023-2343-RC2
AC1: 'Comment on egusphere-2023-2343', Kelley Barsanti, 05 Jul 2024

We thank the reviewers for their time and attention. We have uploaded our responses and look forward to the editor's decision.

Citation: https://doi.org/10.5194/egusphere-2023-2343-AC1

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Kelley Barsanti on behalf of the Authors (09 Jul 2024) Author's response Author's tracked changes Manuscript

ED: Publish as is (14 Jul 2024) by Qiang Zhang

AR by Kelley Barsanti on behalf of the Authors (18 Jul 2024) Manuscript

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Short summary

This paper describes the scientific basis for gas-phase atmospheric chemical mechanisms derived using the SAPRC mechanism generation system, MechGen. It can derive mechanisms for most organic compounds with C, H, O, or N atoms, including initial reactions of organics with OH, O₃, NO₃, and O³P or by photolysis, as well as the reactions of the various types of intermediates that are formed. The paper includes a description of areas of uncertainty where additional research and updates are needed.