Sherwen, Tomás orcid.org/0000-0002-3006-3876, Evans, Mathew John orcid.org/0000-0003-4775-032X, Carpenter, Lucy Jane orcid.org/0000-0002-6257-3950 et al. (2 more authors) (2016) Halogen chemistry reduces tropospheric O3 radiative forcing. Atmospheric Chemistry and Physics Discussions. ISSN 1680-7367
Abstract
Tropospheric ozone (O3) is a global warming gas, however the lack of a firm observational record since the preindustrial period means that estimates of its radiative forcing (RFTO3) rely on model calculations. Recent observational evidence shows that halogens are pervasive in the troposphere and need to be represented in chemistry-transport models for an accurate simulation of present-day O3. Using the GEOS-Chem model we show that tropospheric halogen chemistry is more active in the present-day than in the pre-industrial. This is due to increased oceanic iodine emissions driven by increased surface O3, higher anthropogenic emissions of bromo-carbons and an increased flux of bromine from the stratosphere. We calculate pre-industrial to present-day increases in the tropospheric O3 burden of 113 Tg without halogens but only 95 Tg with, leading to a reduction in RFTO3 from 0.432 to 0.366 W m−2. We attribute ~ 40 % of this reduction to the ocean-atmosphere iodine feedback, ~ 30 % to increased anthropogenic halogens in the troposphere and ~ 30 % to increased bromine flux from the stratosphere. This reduction of RFTO3 (0.066 W m−2) is greater than that from stratospheric ozone (~ 0.05 W m−2). Estimates of RFTO3 that fail to consider halogen chemistry are likely overestimates (~ 20 %).
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © Author(s) 2016 |
Keywords: | halogens,radiative forcing,CLIMATE CHANGE,iodine,bromine,chlorine,troposphere,STRATOSPHERE,ozone |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) |
Depositing User: | Pure (York) |
Date Deposited: | 26 Aug 2016 09:29 |
Last Modified: | 21 Jan 2025 17:22 |
Published Version: | https://doi.org/10.5194/acp-2016-688 |
Status: | Published |
Refereed: | No |
Identification Number: | 10.5194/acp-2016-688 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:103497 |