the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 14 Feb 2025
Observationally Constrained Analysis on the Distribution of Fine and Coarse Mode Nitrate in Global Climate Models
Abstract. Nitrate plays an important role in the Earth’s climate and air quality. A key challenge in simulating the lifecycle of nitrate aerosol in global climate models is to accurately represent mass size distribution of nitrate aerosol. In this study, we evaluate the performance of the Energy Exascale Earth System Model version 2 (E3SMv2) and the Community Earth System Model version 2 (CESM2), along with Aerosol Comparisons between Observations and Models (AeroCom) phase III models, in simulating spatial distribution of fine-mode nitrate, mass size distribution of fine- and coarse-mode nitrate, and the gas-aerosol partitioning between nitric acid gas and nitrate, using long-term ground-based observations and measurements from multiple aircraft campaigns. We find that most models underestimate the annual mean PM2.5 (particulate matter with diameter less than 2.5 μm) nitrate surface concentration averaged over all sites. The observed nitrate PM2.5/PM10 and PM1/PM4 ratios are influenced by the relative contribution of fine sulfate/organic particles and coarse dust/sea salt particles. Overall, the ground-based observations give an annual mean surface nitrate PM2.5/PM10 ratio of 0.7. Most models underestimate the annual mean PM2.5/PM10 ratio in all regions. There are large spreads in the modeled nitrate PM1/PM4 ratios, which span the full range from 0 to 1. Most models underestimate the surface molar ratio of nitrate to total inorganic nitrate averaged across all sites. Our study indicates the importance of gas-aerosol partition parameterization and simulation of dust and sea salt in correctly simulating mass size distribution of nitrate.
Competing interests: Some co-authors are members of the editorial board of Atmospheric Chemistry and Physics. The authors have no other competing interests to declare.
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.-
Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(9269 KB) - Metadata XML
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Supplement
(2486 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-235', Anonymous Referee #1, 21 Feb 2025
Particulate nitrate plays a critical role in aerosol radiative forcing, and leads to very large uncertainty in climate projection. But very few global climate models have nitrate included, and only sparse studies evaluated the nitrate simulation performance. This work provides a comprehensive evaluation of the nitrate simulation in six global climate models again in-situ observations over north American, Australia, Japan and south Asia, Europe and Africa. This work not only evaluate the simulation of nitrate mass concentration at the surface level, but also for the vertical profile and gas-aerosol partitioning of nitrate. I think this work fits well with the scope of ACP. Although the scientific value is appreciated for this work, I would like to make a few suggestion hopeful could help improve the presentation of this article for publishing in ACP.
1) IPCC AR5 2013 is referred. I recommend refer to the latest IPCC AR6 2021, to keep the research up to date.
2) Line 75-77. This sentence is not clear. Please rephrase it.
3) Thanks for providing comprehensive review of previous studies in nitrate simulation, in the Introduction section. However, the presentation, or the writing style, would need some improvement. Rather than just listing what has been done previously (e.g., L80-90, and many other), but also better to summarize a key message you would like to express to audience.
4) “MOSAIC explicit treats the heterogeneous reactions on HNO3 on dust and sea salt particles …”. What about particles of other species? Are reactions treated independently for each size mode, or a bulk treatment for particles spanning all modes?
5) Line-150. Why? Or you may want citation here to support your argument.
6) last line of page-6. Change to “with 1 year spin-up and the last 10-year results for analysis”.
7) Line 184. Should be Table-2?
8) In the discussion, where possible, better to briefly engage some discussion about ammonia, sulfate, sea-salt and dust simulations. Since, this could help point towards clearer directions for improving nitrate simulation. Excessive ammonia after neutralizes sulfuric acid can then contribute to particulate nitrate.
Citation: https://doi.org/10.5194/egusphere-2025-235-RC1 - RC2: 'Comment on egusphere-2025-235', Anonymous Referee #2, 24 Mar 2025
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AC1: 'Comment on egusphere-2025-235', Mingxuan Wu, 20 Jun 2025
We thank the two anonymous reviewers for their valuable comments and constructive suggestions on the manuscript. In the attached document, we explain how the comments and suggestions are addressed and highlight revisions made in the revised manuscript. The reviewers’ comments are in blue color. Our responses are in black, and our corresponding revisions in the manuscript are in red.
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-235', Anonymous Referee #1, 21 Feb 2025
Particulate nitrate plays a critical role in aerosol radiative forcing, and leads to very large uncertainty in climate projection. But very few global climate models have nitrate included, and only sparse studies evaluated the nitrate simulation performance. This work provides a comprehensive evaluation of the nitrate simulation in six global climate models again in-situ observations over north American, Australia, Japan and south Asia, Europe and Africa. This work not only evaluate the simulation of nitrate mass concentration at the surface level, but also for the vertical profile and gas-aerosol partitioning of nitrate. I think this work fits well with the scope of ACP. Although the scientific value is appreciated for this work, I would like to make a few suggestion hopeful could help improve the presentation of this article for publishing in ACP.
1) IPCC AR5 2013 is referred. I recommend refer to the latest IPCC AR6 2021, to keep the research up to date.
2) Line 75-77. This sentence is not clear. Please rephrase it.
3) Thanks for providing comprehensive review of previous studies in nitrate simulation, in the Introduction section. However, the presentation, or the writing style, would need some improvement. Rather than just listing what has been done previously (e.g., L80-90, and many other), but also better to summarize a key message you would like to express to audience.
4) “MOSAIC explicit treats the heterogeneous reactions on HNO3 on dust and sea salt particles …”. What about particles of other species? Are reactions treated independently for each size mode, or a bulk treatment for particles spanning all modes?
5) Line-150. Why? Or you may want citation here to support your argument.
6) last line of page-6. Change to “with 1 year spin-up and the last 10-year results for analysis”.
7) Line 184. Should be Table-2?
8) In the discussion, where possible, better to briefly engage some discussion about ammonia, sulfate, sea-salt and dust simulations. Since, this could help point towards clearer directions for improving nitrate simulation. Excessive ammonia after neutralizes sulfuric acid can then contribute to particulate nitrate.
Citation: https://doi.org/10.5194/egusphere-2025-235-RC1 - RC2: 'Comment on egusphere-2025-235', Anonymous Referee #2, 24 Mar 2025
-
AC1: 'Comment on egusphere-2025-235', Mingxuan Wu, 20 Jun 2025
We thank the two anonymous reviewers for their valuable comments and constructive suggestions on the manuscript. In the attached document, we explain how the comments and suggestions are addressed and highlight revisions made in the revised manuscript. The reviewers’ comments are in blue color. Our responses are in black, and our corresponding revisions in the manuscript are in red.
Peer review completion
Journal article(s) based on this preprint
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Zheng Lu
Xiaohong Liu
Huisheng Bian
David Cohen
Mian Chin
Didier A. Hauglustaine
Vlassis A. Karydis
Marianne T. Lund
Gunnar Myhre
Andrea Pozzer
Michael Schulz
Ragnhild B. Skeie
Alexandra P. Tsimpidi
Svetlana G. Tsyro
Shaocheng Xie
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(9269 KB) - Metadata XML
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Supplement
(2486 KB) - BibTeX
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- Final revised paper