Preprints
https://doi.org/10.5194/egusphere-2025-4664
https://doi.org/10.5194/egusphere-2025-4664
26 Sep 2025
 | 26 Sep 2025

PAMS-Constrained Top-Down Calibration of VOC-Speciated CMAQ Simulations

Sheng-Po Chen, Chieh-Heng Wang, Yi-Yu Lee, Feng-Yi Cheng, and Jia-Lin Wang

Abstract. Accurate simulation of volatile organic compound (VOC) emissions and their role in ozone (O3) formation remains a persistent challenge in chemical transport models (CTMs). Most models rely on lumped surrogate species, limiting their ability to represent speciated VOCs and directly compare with observations. In this study, we develop an enhanced version of the Community Multiscale Air Quality model, termed CMAQ-PAMS, which explicitly incorporates 54 VOC species targeted by the Photochemical Assessment Monitoring Stations (PAMS) network in Taiwan.

We evaluate model performance during a representative high-ozone event in fall 2021 and apply a top-down calibration approach using hourly VOC data from 12 PAMS sites. The original simulation (OrigSIM) significantly misrepresents key species, largely due to reliance on U.S.-based speciation profiles. After adjustment, the modified simulation (ModSIM) shows substantial improvements in both individual species concentrations and group-level composition (e.g., alkanes, aromatics). Notably, acetylene, a key tracer of incomplete combustion, was underestimated in OrigSIM but successfully recovered in ModSIM.

Despite accounting for only ~32 % of total VOC emissions, PAMS species contribute up to 52 % of modeled domestic O3 formation, highlighting their disproportionate impact in VOC-limited regimes. Additionally, the CMAQ-PAMS framework enables the use of diagnostic ratios (e.g., propylene/acetylene) to identify emission sources and assess air mass aging. These findings underscore the importance of localized VOC profiling and demonstrate that the PAMS-constrained CMAQ-PAMS model provides a more chemically detailed and observationally anchored platform for ozone modeling and regulatory applications.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Journal article(s) based on this preprint

22 Apr 2026
PAMS-constrained top-down calibration of VOC-speciated CMAQ simulations
Sheng-Po Chen, Chieh-Heng Wang, Yi-Ju Lee, Fang-Yi Cheng, and Jia-Lin Wang
Atmos. Chem. Phys., 26, 5497–5516, https://doi.org/10.5194/acp-26-5497-2026,https://doi.org/10.5194/acp-26-5497-2026, 2026
Short summary
Sheng-Po Chen, Chieh-Heng Wang, Yi-Yu Lee, Feng-Yi Cheng, and Jia-Lin Wang

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-4664', Anonymous Referee #1, 30 Oct 2025
  • RC2: 'Comment on egusphere-2025-4664', Anonymous Referee #2, 05 Nov 2025
  • AC1: 'Comment on egusphere-2025-4664', ShengPo Chen, 19 Dec 2025
  • AC2: 'Comment on egusphere-2025-4664', ShengPo Chen, 19 Dec 2025
  • AC3: 'Comment on egusphere-2025-4664', ShengPo Chen, 19 Dec 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-4664', Anonymous Referee #1, 30 Oct 2025
  • RC2: 'Comment on egusphere-2025-4664', Anonymous Referee #2, 05 Nov 2025
  • AC1: 'Comment on egusphere-2025-4664', ShengPo Chen, 19 Dec 2025
  • AC2: 'Comment on egusphere-2025-4664', ShengPo Chen, 19 Dec 2025
  • AC3: 'Comment on egusphere-2025-4664', ShengPo Chen, 19 Dec 2025

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
AR by Sheng-Po Chen on behalf of the Authors (19 Dec 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (27 Dec 2025) by Kelvin Bates
RR by Anonymous Referee #2 (29 Dec 2025)
ED: Publish as is (29 Dec 2025) by Kelvin Bates
AR by Sheng-Po Chen on behalf of the Authors (04 Jan 2026)  Manuscript 

Journal article(s) based on this preprint

22 Apr 2026
PAMS-constrained top-down calibration of VOC-speciated CMAQ simulations
Sheng-Po Chen, Chieh-Heng Wang, Yi-Ju Lee, Fang-Yi Cheng, and Jia-Lin Wang
Atmos. Chem. Phys., 26, 5497–5516, https://doi.org/10.5194/acp-26-5497-2026,https://doi.org/10.5194/acp-26-5497-2026, 2026
Short summary
Sheng-Po Chen, Chieh-Heng Wang, Yi-Yu Lee, Feng-Yi Cheng, and Jia-Lin Wang
Sheng-Po Chen, Chieh-Heng Wang, Yi-Yu Lee, Feng-Yi Cheng, and Jia-Lin Wang

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Short summary
Current chemical transport models often simplify chemical compounds, making it hard to match real-world observations. In this study, we enhanced a model to simulate 54 specific volatile organic compounds (VOCs) measured across Taiwan. By comparing with detailed monitoring data, we corrected emissions and improved predictions of VOCs. The results indicate that a small set of compounds has a significant impact on ozone, providing guidance for more effective air quality strategies.
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