Future trends in stratosphere-to-troposphere transport in CCMI models
Name
acp-20-6883-2020.pdf
Description
Published version
Size
14.66 MB
Format
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Checksum (MD5)
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Author(s)
Abalos, Marta
Orbe, Clara
Kinnison, Douglas E
Plummer, David
Oman, Luke D
Jöckel, Patrick
Morgenstern, Olaf
Garcia, Rolando R
Zeng, Guang
Stone, Kane A
Date Issued
June 11, 2020
Journal
Atmospheric Chemistry and Physics
Publisher
Copernicus GmbH
Citation
Abalos, M., Orbe, C., Kinnison, D. E., Plummer, D., Oman, L. D., Jöckel, P., Morgenstern, O., Garcia, R. R., Zeng, G., Stone, K. A., and Dameris, M.: Future trends in stratosphere-to-troposphere transport in CCMI models, Atmos. Chem. Phys., 20, 6883–6901.
Version
Final published version
Abstract
One of the key questions in the air quality and climate sciences is how tropospheric ozone concentrations will change in the future. This will depend on two factors: changes in stratosphere-to-troposphere transport (STT) and changes in tropospheric chemistry. Here we aim to identify robust changes in STT using simulations from the Chemistry Climate Model Initiative (CCMI) under a common climate change scenario (RCP6.0). We use two idealized stratospheric tracers to isolate changes in transport: stratospheric ozone (O3S), which is exactly like ozone but has no chemical sources in the troposphere, and st80, a passive tracer with fixed volume mixing ratio in the stratosphere. We find a robust increase in the tropospheric columns of these two tracers across the models. In particular, stratospheric ozone in the troposphere is projected to increase 10 %–16 % by the end of the 21st century in the RCP6.0 scenario. Future STT is enhanced in the subtropics due to the strengthening of the shallow branch of the Brewer–Dobson circulation (BDC) in the lower stratosphere and of the upper part of the Hadley cell in the upper troposphere. The acceleration of the deep branch of the BDC in the Northern Hemisphere (NH) and changes in eddy transport contribute to increased STT at high latitudes. These STT trends are caused by greenhouse gas (GHG) increases, while phasing out of ozone-depleting substances (ODS) does not lead to robust transport changes. Nevertheless, the decline of ODS increases the reservoir of ozone in the lower stratosphere, which results in enhanced STT of O3S at middle and high latitudes. A higher emission scenario (RCP8.5) produces stronger STT trends, with increases in tropospheric column O3S more than 3 times larger than those in the RCP6.0 scenario by the end of the 21st century.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Creative Commons Attribution
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DOI of Published Version
https://doi.org/10.5194/acp-20-6883-2020
