Preprints
https://doi.org/10.5194/acp-2021-569
https://doi.org/10.5194/acp-2021-569

  20 Jul 2021

20 Jul 2021

Review status: this preprint is currently under review for the journal ACP.

A Model Intercomparison of Stratospheric Solar Geoengineering by Accumulation-Mode Sulfate Aerosols

Debra K. Weisenstein1,, Daniele Visioni3, Henning Franke4, Ulrike Niemeier4, Sandro Vattioni2, Gabriel Chiodo2, Thomas Peter2, and David W. Keith1 Debra K. Weisenstein et al.
  • 1Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA-02138, USA
  • 2Institute of Atmospheric and Climate Science, ETH Zürich, Zurich, 8002, Switzerland
  • 3Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY-14850, USA
  • 4Max Planck Institute for Meteorology, Hamburg, 20146, Germany
  • retired

Abstract. Analyses of stratospheric solar geoengineering have focused on sulfate aerosol, and almost all climate model experiments on sulfate aerosol have assumed injection of SO2. Yet continuous injection of SO2 may produce overly large aerosols. Injection of SO3 or H2SO4 from an aircraft in stratospheric flight is expected to produce new accumulation-mode particles (AM-H2SO4), and such injection may allow the sulfate aerosol size distribution to be nudged towards higher radiative efficacy. We report the first multi-model intercomparison of AM-H2SO4 injection. We compare three models: CESM2(WACCM), MAECHAM5-HAM, and SOCOL-AER coordinated as a testbed experiment within the Geoengineering Model Intercomparison Project (GeoMIP). The intercomparison explores how the injection of new accumulation-mode particles changes the large-scale particle size distribution and thus the overall radiative and dynamical response to sulfate aerosol injection. Each model used the same injection scenarios testing AM-H2SO4 and SO2 injections at 5 and 25 Tg(S) yr−1 to test linearity and climate response sensitivity. All three models find that AM-H2SO4 injection increases the radiative efficacy, defined as the radiative forcing per unit of sulfur injection, relative to SO2 injection. Increased radiative efficacy means that when compared to the use of SO2 to produce the same radiative forcing, AM-H2SO4 emissions could reduce some side-effects of sulfate aerosol geoengineering such as stratospheric heating. We explore the sensitivity to injection pattern by comparing injection at two points at 30° N and 30° S to injection in a belt along the equator between 30° S and 30° N, and find opposite impacts on radiative efficacy for AM-H2SO4 and SO2, suggesting that prior model results for concentrated injection of SO2 may be strongly dependent on model resolution. Model differences arise from differences in aerosol formulation and differences in model transport and resolution, factors whose interplay cannot be easily untangled by this intercomparison.

Debra K. Weisenstein et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-569', Sandip Dhomse, 12 Aug 2021
  • RC2: 'Comment on acp-2021-569', Anonymous Referee #2, 24 Aug 2021
  • RC3: 'Comment on acp-2021-569', Anonymous Referee #3, 06 Sep 2021

Debra K. Weisenstein et al.

Debra K. Weisenstein et al.

Viewed

Total article views: 540 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
383 147 10 540 3 5
  • HTML: 383
  • PDF: 147
  • XML: 10
  • Total: 540
  • BibTeX: 3
  • EndNote: 5
Views and downloads (calculated since 20 Jul 2021)
Cumulative views and downloads (calculated since 20 Jul 2021)

Viewed (geographical distribution)

Total article views: 558 (including HTML, PDF, and XML) Thereof 558 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 16 Oct 2021
Download
Short summary
This paper explores a potential method of solar radiation management that could be used to slow the rate of change of climate over decades to a century. We use three climate models to compare injections of accumulation-mode sulfuric acid aerosol particulate with injections of SO2 gas and, find that injection of accumulation-mode aerosol particles produces a greater change in radiative forcing per unit sulfur injected than an equivalent injection of gas phase SO2.
Altmetrics