Publication Abstracts
McGraw and Polvani 2026, in press
, and L.M. Polvani, 2026: Direct radiative impacts of stratospheric aerosols on the tropical troposphere: Clouds, precipitation, and circulation in convection-resolving and global simulations. J. Climate, in press, doi:10.1175/JCLI-D-25-0688.1.
A concern for stratospheric aerosol injection (SAI) is that stratospheric aerosols could inadvertently alter rain and winds through mechanisms independent of the intended surface cooling. Here we investigate how the tropical troposphere responds to SAI in models of different complexity, including convection-resolving mock-Walker and small-domain simulations as well as a global climate model, with sea surface temperature held fixed. Across models, we trace the mechanisms driving tropospheric impacts and identify modeling limitations that hinder accurate risk evaluation. SAI enhances downward longwave radiation from the warmed, aerosol-rich stratosphere, generating upper-tropospheric radiative heating that reduces cloudiness and suppresses convection, reducing precipitation. While our best estimate is a ~2% tropical mean precipitation reduction under strong SAI at fixed sea surface temperature, this is counteracted by cloud radiative responses that hinder predictability. Further, sensitivity experiments suggest that the precipitation response may hinge on how SAI is enacted, with higher and smaller particles both tending to weaken the precipitation response, in partial agreement with prior findings. Our convection-resolving simulations do not show that surface-temperature-independent effects of stratospheric aerosols inherently weaken the tropical overturning circulation, as previously suggested. While regional precipitation responses within the tropics could be substantial, our simulations suggest potential for lower risks than analogous volcanic events by releasing aerosols gradually, thereby mitigating land-sea circulation responses. These results clarify the mechanisms governing SAI hydroclimate impacts, and reveal limitations affecting simulated outcomes from contemporary models. Consequently, near-term SAI deployment would carry the risk of being implemented without the ability to reliably predict its hydroclimate impacts.
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BibTeX Citation
@unpublished{mc02400q,
author={McGraw, Z. and Polvani, L. M.},
title={Direct radiative impacts of stratospheric aerosols on the tropical troposphere: Clouds, precipitation, and circulation in convection-resolving and global simulations},
year={2026},
journal={Journal of Climate},
doi={10.1175/JCLI-D-25-0688.1},
note={Manuscript accepted for publication}
}
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RIS Citation
TY - INPR ID - mc02400q AU - McGraw, Z. AU - Polvani, L. M. PY - 2026 TI - Direct radiative impacts of stratospheric aerosols on the tropical troposphere: Clouds, precipitation, and circulation in convection-resolving and global simulations JA - J. Climate JO - Journal of Climate DO - 10.1175/JCLI-D-25-0688.1 ER -
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