CESM2/CARMA Cloud and CARMA Aerosol Model Descriptions

Zhu, Yunqian; Liu, Cheng-Cheng; Bardeen, Charles; Wang, Lu; Tilmes, Simone; Quaglia, Ilaria; Maloney, Christopher M.; Vitt, Francis; Toon, Owen Brian

doi:10.22541/essoar.177135577.71771059/v1

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https://doi.org/10.22541/essoar.177135577.71771059/v1

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11 Mar 2026

| 11 Mar 2026

Status: this preprint is open for discussion and under review for Geoscientific Model Development (GMD).

CESM2/CARMA Cloud and CARMA Aerosol Model Descriptions

Yunqian Zhu, Cheng-Cheng Liu, Charles Bardeen, Lu Wang, Simone Tilmes, Ilaria Quaglia, Christopher M. Maloney, Francis Vitt, and Owen Brian Toon

Abstract. The Community Aerosol and Radiation Model for Atmospheres (CARMA) is a sectional microphysical model widely used to understand the formation of aerosols and clouds. This paper is an updated description of the CARMA model algorithms since Toon et al 1988, with examples from the newly developed CARMA Cloud model. This paper describes the general algorithms and solvers for nucleation, condensation/evaporation, coagulation, and sedimentation shared among all CARMA aerosols and clouds models; specific microphysical processes needed for water droplet and ice; how the CARMA Cloud is set up and how it interacts with other processes inside the Community Earth System Model.

Received: 02 Mar 2026 – Discussion started: 11 Mar 2026

Yunqian Zhu, Cheng-Cheng Liu, Charles Bardeen, Lu Wang, Simone Tilmes, Ilaria Quaglia, Christopher M. Maloney, Francis Vitt, and Owen Brian Toon

Status: open (until 06 May 2026)

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CEC1:
'Comment on egusphere-2026-1185', Astrid Kerkweg, 01 Apr 2026 reply
Dear authors,
in my role as Executive editor of GMD, I would like to bring to your attention our Editorial version 1.2: https://www.geosci-model-dev.net/12/2215/2019/
This highlights some requirements of papers published in GMD, which is also available on the GMD website in the ‘Manuscript Types’ section: http://www.geoscientific-model-development.net/submission/manuscript_types.html
In particular, please note that for your paper, the following requirement has not been met in the Discussions paper:
"The main paper must give the model name and version number (or other unique identifier) in the title."

Code must be published on a persistent public archive with a unique identifier for the exact model version described in the paper or uploaded to the supplement, unless this is impossible for reasons beyond the control of authors. All papers must include a section, at the end of the paper, entitled "Code availability". Here, either instructions for obtaining the code, or the reasons why the code is not available should be clearly stated. It is preferred for the code to be uploaded as a supplement or to be made available at a data repository with an associated DOI (digital object identifier) for the exact model version described in the paper. Alternatively, for established models, there may be an existing means of accessing the code through a particular system. In this case, there must exist a means of permanently accessing the precise model version described in the paper. In some cases, authors may prefer to put models on their own website, or to act as a point of contact for obtaining the code. Given the impermanence of websites and email addresses, this is not encouraged, and authors should consider improving the availability with a more permanent arrangement. Making code available through personal websites or via email contact to the authors is not sufficient. After the paper is accepted the model archive should be updated to include a link to the GMD paper.

Please provide the version number of CARMA in the title of your revised manuscript.
As GitHub is not a persistent archive, please provide a persistent release for the exact source code versions for CARMA and CESM/CARMA used for the publication in this paper. As explained in https://www.geoscientific-model-development.net/about/manuscript\_types.html the preferred reference to this release is through the use of a DOI which then can be cited in the paper. For projects in GitHub a DOI for a released code version can easily be created using Zenodo, see https://guides.github.com/activities/citable-code/ for details. Finally note, that according to our new Editorial (v1.2) all data and analysis / plotting scripts should be made available.
Additionally, the part of the model output on which the results of your paper are based need to be made pupblicly available.
Yours,
Astrid Kerkweg

Reply
Citation: https://doi.org/10.5194/egusphere-2026-1185-CEC1
- AC1: 'Reply on CEC1', Yunqian Zhu, 01 Apr 2026 reply
  
  Dear Editor, thank you for the comments.
  1. the CARMA version is version 4, which will be add to the title during the revision.
  2. We created a new permanent doi to archive the model code:
  
  NCAR CARMA Group, & Owen Brian Toon Research group. (2026). Community Aerosol and Radiation Model for Atmospheres (CARMA) standalone 4.11 code. University of Colorado Boulder. https://doi.org/10.25810/SNMH-NW73
  3. And the data for the output are achived at: Zhu, Y. (2026). CARMA Cloud model standalone test results [Data set]. Zenodo. https://doi.org/10.5281/zenodo.19373048
  
  Reply
  
  Citation: https://doi.org/10.5194/egusphere-2026-1185-AC1

Yunqian Zhu, Cheng-Cheng Liu, Charles Bardeen, Lu Wang, Simone Tilmes, Ilaria Quaglia, Christopher M. Maloney, Francis Vitt, and Owen Brian Toon

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Short summary

The Community Aerosol and Radiation Model for Atmospheres (CARMA) is a sectional microphysical model widely used to study the formation of aerosols and clouds. This paper presents an update to the CARMA model algorithms since Toon et al. 1988, with a focus on the newly developed CARMA Cloud model.


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