Preprints
https://doi.org/10.5194/egusphere-2025-145
https://doi.org/10.5194/egusphere-2025-145
14 Mar 2025
 | 14 Mar 2025

A REtrieval Method for optical and physical Aerosol Properties in the stratosphere (REMAPv1)

Andrin Jörimann, Timofei Sukhodolov, Beiping Luo, Gabriel Chiodo, Graham Mann, and Thomas Peter

Abstract. The stratospheric aerosol is an important climate forcing agent as it scatters some of the incoming solar radiation back to space, thus cooling the Earth’s surface and the troposphere. At the same time it absorbs some of the upwelling terrestrial radiation, which heats the stratosphere. It also plays an important role in stratospheric ozone chemistry by hosting heterogeneous reactions. Major volcanic eruptions can cause strong perturbations of stratospheric aerosol, changing its radiative and chemical effects by more than an order of magnitude. Many global climate models require prescribed stratospheric aerosol as input to properly simulate both climate effects in the presence and absence of volcanic eruptions. This paper describes REMAP, a retrieval method and code for aerosol properties that has been used in several model intercomparison projects (under the name SAGE-3/4λ). The code fits a single-mode log-normal size distribution for a pure aqueous sulfuric acid aerosol to aerosol extinction coefficients from observational or model data sets. From the retrieved size distribution parameters the code calculates the effective radius, surface area density, as well as extinction coefficients, single-scattering albedos and asymmetry factors of the aerosol within the wavelength bands specified by individual climate models. We validate the REMAP using balloon observations after the Pinatubo and Hunga-Tonga Hunga Ha’apai volcanic eruptions, as well as four decades of LIDAR measurements. Within the constraints of a single-mode log-normal distribution REMAP generates realistic effective radii and surface area densities after volcanic eruptions and generally matches the LIDAR backscatter time series within measurement uncertainty. Deviations in aerosol backscatter up to a factor of 2 arise when (non-volcanic) tropospheric intrusions (e.g. from wildfires) are present and their composition deviates significantly from the background type. We describe the products that have been used in CCMI, CMIP6 and other model intercomparison projects, and provide practical instructions for use of the code.

Competing interests: At least one of the (co-)authors is a member of the editorial board of Geoscientific Model Development. The peer-review process was guided by an independent editor, and the authors also 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.
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Journal article(s) based on this preprint

16 Sep 2025
REtrieval Method for optical and physical Aerosol Properties in the stratosphere (REMAPv1)
Andrin Jörimann, Timofei Sukhodolov, Beiping Luo, Gabriel Chiodo, Graham Mann, and Thomas Peter
Geosci. Model Dev., 18, 6023–6041, https://doi.org/10.5194/gmd-18-6023-2025,https://doi.org/10.5194/gmd-18-6023-2025, 2025
Short summary
Andrin Jörimann, Timofei Sukhodolov, Beiping Luo, Gabriel Chiodo, Graham Mann, and Thomas Peter

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-145', Anonymous Referee #1, 03 Apr 2025
  • RC2: 'Comment on egusphere-2025-145', Anonymous Referee #2, 24 Apr 2025
  • AC1: 'Comment on egusphere-2025-145', Andrin Jörimann, 07 Jun 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-145', Anonymous Referee #1, 03 Apr 2025
  • RC2: 'Comment on egusphere-2025-145', Anonymous Referee #2, 24 Apr 2025
  • AC1: 'Comment on egusphere-2025-145', Andrin Jörimann, 07 Jun 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Andrin Jörimann on behalf of the Authors (09 Jun 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (18 Jun 2025) by Jason Williams
AR by Andrin Jörimann on behalf of the Authors (20 Jun 2025)

Journal article(s) based on this preprint

16 Sep 2025
REtrieval Method for optical and physical Aerosol Properties in the stratosphere (REMAPv1)
Andrin Jörimann, Timofei Sukhodolov, Beiping Luo, Gabriel Chiodo, Graham Mann, and Thomas Peter
Geosci. Model Dev., 18, 6023–6041, https://doi.org/10.5194/gmd-18-6023-2025,https://doi.org/10.5194/gmd-18-6023-2025, 2025
Short summary
Andrin Jörimann, Timofei Sukhodolov, Beiping Luo, Gabriel Chiodo, Graham Mann, and Thomas Peter

Data sets

REMAPv1 Andrin Jörimann https://www.research-collection.ethz.ch/handle/20.500.11850/713396

SAGE-4λv2 Beiping Luo https://doi.org/10.3929/ethz-b-000714581

SAGE-3λv4 Beiping Luo https://doi.org/10.3929/ethz-b-000715155

REMAP-CCMI-2022-ref Beiping Luo https://doi.org/10.3929/ethz-b-000715176

REMAP-CCMI-2022-sai Andrin Jörimann https://doi.org/10.3929/ethz-b-000714654

REMAP-GloSSAC-2023 Andrin Jörimann https://doi.org/10.3929/ethz-b-000713396

Andrin Jörimann, Timofei Sukhodolov, Beiping Luo, Gabriel Chiodo, Graham Mann, and Thomas Peter

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Short summary
Aerosol particles in the stratosphere affect our climate. Climate models therefore need an accurate description of their properties and evolution. Satellites measure how strongly aerosol particles extinguish light passing through the stratosphere. We describe a method to use such aerosol extinction data to retrieve the number and sizes of the aerosol particles and calculate their optical effects. The resulting data sets for models are validated against ground-based and balloon observations.
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